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Slim3 (Automotive) (OP)
19 Jan 12 2:30
Water injection-
I received a DOE grant in 1980 to build an alcohol still and convert a car to run on straight alcohol. I made 160 proof alcohol and purchased 200 proof to run tests with the car. After tuning the engine (modified to run on alcohol) I ran tests on 200 proof, 190, 180 and 170 proof tuning for each mixture.

I found that in 1/4 mile acceleration tests, (3 each) there was very little difference between the 200 proof and the 170 proof runs which puzzled me as I had displaced 15% of my fuel with water in the 170 proof.

It was suggested that the water in the 170 was going into the combustion chamber as a liquid and turning to steam which replaced the 15% heat expansion from the fuel burn thus maintaining the power. Even though it lowered combustion chamber temp it still performed the same. I suspect that the steam expansion out performed the gas expansion.

This made me install a aux water injection system on two 318 Dodge engine trucks and run the same tests and they also produced more power then just on gasoline.

It was noted that the engine in poor condition raised in power more then the good engine.

I made no fuel mileage tests.
   
patprimmer (Publican)
19 Jan 12 3:41
If your alcohol contains 15% water, you need to increase fuel delivery by about 15% to avoid a lean out. In that case, you burn the same amount of fuel with the water along for t5he ride.

The water will effectively raise the octane rating of the fuel so you can use higher compression or more ignition advance to gain some power

Regards
Pat
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Slim3 (Automotive) (OP)
19 Jan 12 10:35
The compression ratio had been raised to make use of the higher octane rating of alcohol and the ignition timing was reset for each different proof. The dual Stromberg carburetors have metering needles so it was easy to adjust to each proof.

Even though I did not conduct fuel mileage tests, I was using a small one gallon tank mounted under the hood to make all the runs. (three on each proof tested) Each proof received three full throttle 1/4 mile runs and three driving runs back and did not note much difference in fuel used between the different proofs.

Before the engine modifications I made test runs in the same 1/4 mile full throttle runs, to get a bench mark of performance and using the same on gallon fuel tank.

I did note more of the amount of alcohol blends was used then the straight gasoline, which I expected. However it was not the 96% more expected due to the 96% larger jet (volume not diameter). Due to the lower BTU content in alcohol. I contributed this to the higher compression ratio used on the alcohol blends producing a more efficient use of fuel coupled with the shorter time on the track (less actual revolutions of the engine through each run).

I do wish I had conducted controlled fuel mileage tests. However by the time I finished the tests of the still and car, fuel prices came down and potential investors all said, "Fuel prices came down, why bother?".  
 
MiketheEngineer (Structural)
19 Jan 12 13:41
During WWII - many piston engines were equipped with water injection.  I think some high performance racing planes still do.

There were some varying theories.

1.  The "weight" of the water increased compression...
2.  The heat from the engine actually turned the water back into hydrogen and oxygen.

Never found a good answer about this.
Helpful Member!  patprimmer (Publican)
20 Jan 12 0:19
The real reason is the latent heat of vaporisation of the water reduces peak temperatures and suppresses detonation, so more boost or higher compression could be used. The boost and/or compression is what gave the extra power, not the water per-say. The water simply had the effect of increasing octane.

Water injection is still used on high boost engines as a detonation suppressant.

Regards
Pat
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Slim3 (Automotive) (OP)
20 Jan 12 1:22
When I received the DOE Grant a company in the SC sent me several water injection add on systems to try. They said a 50/50 Alcohol/Water mix worked best on gasoline and diesel engines. I tried several combinations on a gas engine (318 Dodge). I tried straight water, 50/50 alcohol/water and straight alcohol and the results confirmed what they said.

A 50/50 alcohol/water (100 proof) produced the most power when injected into the carburetor of a gasoline engine.

No adjustments were made to the engine and only acceleration tests were run.

The method of injection was done with a small valve and a rich mixture was injected into the intake until a stumble was noted and then the injection was leaned out until the stumble cleared up. Then the acceleration run was timed.

Probably even better performance could have been achieved if I had taken advantage of an advanced ignition timing as you say.

I only ran the tests as recommended by the company who sent me the systems. I was surprised as I first did not believe them about a 50/50 mix.  
Helpful Member!  jellydonut (Marine/Ocean)
20 Jan 12 2:33
Nowadays water\methanol is used because obviously methanol is easier to sell (and no one's gonna try to drink from your tank!).

Diesel enthusiasts use it to cool EGTs and allow for higher output by injecting more fuel.

In the maritime sector, fuel/water emulsions are used by the large engine companies. The claimed effect of emulsion of water in the fuel is a) cooled combustion chamber resulting in lower EGTs and b) that the rapidly vaporizing/expanding water going over to steam helps to 'crush' the larger diesel globules that weren't sufficiently atomized in the injector, improving combustion and efficiency.

It's all claimed, but when large, old actors like MAN (who indeed funded Rudolf Diesel and let him build his first engine) sell this for actual commercial ships, it has to have some merit. It does at least reduce NOx. From the cooling effect, if nothing else.

The Crower six-stroke engine injected water to turn the engine into a steam engine for two cycles after the four fuel cycles. One would expect that injecting water that vaporizes into steam, expanding with a factor I can't remember at the moment, would provide more torque to the expansion stroke in a regular engine.
Tmoose (Mechanical)
20 Jan 12 12:14
I think if the energy required to turn water into steam was instead applied to heating the air (and whatever other gases are in the air fuel mix) the result would be higher combustion chamber pressure than the steamy condition.  Combustion chamber pressure is what makes torque.
Slim3 (Automotive) (OP)
20 Jan 12 13:41
From my tests of alcohol with 15% water in it and from all that Jellydonut points out, there is plenty enough evidence that water injection can produce a lot of power and added economy.

If we had a catalyst that would truly mix at least 15% water in gasoline and not have any phase separation, that alone would decrease our use of oil nation wide.

 
patprimmer (Publican)
20 Jan 12 17:27
Ummmm

jellydonuts post falls far short of supporting your hypothesis.

He is suggesting that water boiling inside large diesel droplets increases dispersion and reduces droplet size of the diesel fuel. That aids rapid combustion in that case, but does not really transfer over to petrol due to the lower boiling point of petrol and the fine mist already achieved with modern fuel injectors.

Injecting more fuel into a petrol engine can make more power, but ir reduces fuel economy and increases HCs and CO in the exhaust.

The Crower 6 stroke has nothing to do with water added during the first power stroke which is where it would be happening if added to the fuel.

A turbo does not extract wasted energy from the exhaust and turn it into power, unless you use the turbine to drive the car rather than to drive a supercharger. Even then, while extracting the free power, you considerably increase temperature and pressure in the cylinder during the exhaust stroke, thereby using crank power to drive the exhaust stroke against higher pressure and leaving more hot residue in the chamber thereby limiting compression ratio and ignition timing, both of which hit power and economy.

Technology already exists to form water emulsion in petrol.

When measuring fuel economy of a water/alcohol blend injection equipped engine, you also need to count the alcohol burned as fuel burned.

When you boil the water to make steam, you also cool the charge. The steam makes pressure, BUT the converting water to steam cools the charge which by itself reduces pressure, so when you do something to make pressure that absorbs pressure in the process, you quickly disappear into the same orifice as all other perpetual motion machines.  

Regards
Pat
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Slim3 (Automotive) (OP)
21 Jan 12 1:48
That all sounds good on paper but I ran acceleration tests many times and found that the alcohol with 15% water (170 proof) performed just as well as 200 Proof. I know how to tune an engine and tuned the engine on each fuel. That was a Triumph TR-7 with two Stromberg carburetors with adjustable metering needles.

I also ran tests on two different Dodge 318 engine trucks using water injection added to a standard gasoline carburetor and noted improved acceleration runs with plain water and with different ratio mixtures of alcohol and water and all the mixtures improved acceleration times on both trucks and both were tuned.

I am sure that the vaporization of water in a combustion chamber does tend to use some of the heat produced but possibly the expansion of steam out performs the expansion of hot air.

What I do know first hand is that it works.  
Helpful Member!  thruthefence (Aerospace)
21 Jan 12 12:19
To further muddle the issue, here's an article dealing with water/alcohol injection in gas turbine engines, by a Pratt & Whitney engineer. In the article is also a brief description of the  forces at work in a recip as well.

3Cairliners.1996.265@ohare.chicago.com%3E" target="_blank">http://www.kls2.com/cgi-bin/arcfetch?db=sci.aeronautics.airliners&id=%3Cairliners.1996.265@ohare.chicago.com%3E

 
Slim3 (Automotive) (OP)
22 Jan 12 2:43
Thanks Thrusthefence, that article by Pratt & Whitney was informative and the Piston engine part clearly explains why I got more performance from the two Dodge engines by adding water injection. I was only thinking of the steam produced and didn't think about the fact that the latent heat of vaporization of the water in the intake manifold giving the engine a condensed cool charge of intake air. A cheap turbo/super charger.  
140Airpower (Automotive)
2 May 12 13:19
patprimmer, your comments are insightful as always, but I'd like to bring up some additional issues.

"The Crower 6 stroke has nothing to do with water added during the first power stroke which is where it would be happening if added to the fuel."

It is actually quite relevant. An important benefit of the steam stroke in the Crower engine is that the energy comes from heat rejected into the engine metal, obviating the need for a cooling system. This energy normally lost to the atmosphere is partly saved. The example of the amount of water needed to internally cool the Crower engine tells you how much water is needed to similarly cool a 4-stroke with water injection. Studies during WWII investigated the possibility of total internal cooling of aero engines while enjoying the other advantages of water injection. It was found effective at medium and high power, but not practical to carry the necessary weight of water in an aircraft. It was also not possible to run at lean cruise while injecting enough water to completely cool the engine due to rough running (apparently extinguishing the burn). Finally, the added alcohol needed to avoid freezing would compromise the cooling ability of the water (they were not considering converting from AvGas to alcohol). More on internal cooling below.

"A turbo does not extract wasted energy from the exhaust and turn it into power, unless you use the turbine to drive the car rather than to drive a supercharger. Even then, while extracting the free power, you considerably increase temperature and pressure in the cylinder during the exhaust stroke, thereby using crank power to drive the exhaust stroke against higher pressure and leaving more hot residue in the chamber thereby limiting compression ratio and ignition timing, both of which hit power and economy."

Are you discounting the work the turbocharger does in charging the engine, reducing induction losses to negative values (supercharging), thus compensating for exhaust pressure? The greater volume of exhaust flow means it is possible to have a turbo setup run with higher intake pressure than exhaust back-pressure in stationary or constant speed engines that do not have a demand for quick acceleration. Small scrolls and wastegates make auto installations inefficient.
Economy also comes with the smaller, lighter, lower capacity engine and, possibly, lower pumping losses at cruise.
And, of course density gained on the intake side is multiplied during the combustion process into additional power, making a turbo system worthwhile even when not so efficient and despite a lower static CR. But, auto turbo setups are indeed almost never for economy.

"Technology already exists to form water emulsion in petrol."

As far as I know, water/gasoline emulsions are not stable, long-term. Methanol/water is stable, but Methanol/gasoline is unstable in the presence of moisture, even atmospheric humidity.

"When you boil the water to make steam, you also cool the charge. The steam makes pressure, BUT the converting water to steam cools the charge which by itself reduces pressure, so when you do something to make pressure that absorbs pressure in the process, you quickly disappear into the same orifice as all other perpetual motion machines. "

Pat, this is true, but only part of the equation. It ignores the fact of greatly reduced heat rejection as mentioned above. The lower heat rejection shows up as energy of expansion. The saved energy is all converted to additional pressure. This does not translate completely to added power because the peak pressure is lower, as you observe, but the pressure at succeeding parts of the expansion stroke is greater. Overall, it CAN be a gain. Spark advance should be increased.
hemi (Automotive)
2 May 12 21:54

Quote (140Airpower):

But, auto turbo setups are indeed almost never for economy.
I respectfully disagree.  Even in the early days (not counting the very early Buick & Corvair turbos), when turbos were applied to performance applications only, that was usually in an effort to maintain performance while increasing fuel economy, in comparison to the large displacement, N/A alternative (e.g. Turbo Trans-Am, Buick Regal/GN, Mustang GT/SVO, Thunderbird Turbo Coupe).  Not that the economy quest was hugely successful, but it was driven, in part at least, no doubt by CAFE.
Today, this is even more the case.  Case in point, Ford Ecoboost.
The argument is even stronger for diesel applications.  I don't think there has been a diesel automotive application since the 90s that isn't turbocharged.  Few of these can seriously be considered performance, rather than economy oriented.
140Airpower (Automotive)
2 May 12 23:09
hemi, you are correct that turbo-diesels are designed generally for economy. I am not familiar with their parameters. I question if they are optimized for efficient operation of the turbo setup overall, with large scrolls and low back pressure with no wastegates. Do they often have intercoolers? The automotive requirement is for a certain minimum acceleration which tends to preclude the greatest efficiency in the turbo application. Nevertheless, a turbocharged diesel engine in an auto application can give better economy than an equivalent gas engine and that is what counts for calling it an economy engine. The other characteristics like smaller, lighter engine size compared to a non-turbo diesel of equal power may make the whole package more economical with the turbo. Even the use of an intercooler, an energy sink that lowers efficiency, can allow a smaller engine to replace a larger one and the whole package may end up being more economical. So, my statement was probably too sweeping and simplistic.

The high performance cars you mentioned were not economy cars even if they got better mileage than the equivalent performing non-turbo cars and they are more like what I am talking about with respect to a non-efficient turbo installation..
BTW, the earliest turbo auto engines were the Oldsmobile Jetfire (not buick) and Corvair Monza Spyder of 1962, 12 years before Porsche.
Slim3 (Automotive) (OP)
3 May 12 1:29
Lots of great information bouncing around here. I am now studying compressed air as a power source for an engine. I have built a Olds 215 to start on direct injected compressed air and it works well. My next project is a full operating compressed air engine. However to expect any range I had to alter the geometry of the piston engine. It looks good on paper so I will build a proto-type soon.
dgallup (Automotive)
3 May 12 11:50
140Airpower - I would certainly disagree with your assertion that an intercooler is an energy sink that lowers efficiency.  It's been 30+ years but when I was testing class 8 diesel engines the biggest improvement to power and efficiency I could make came from lowering charge air temp (more intercooling).  It allowed more power and better BSFC within the cylinder pressure, exhaust gas temp and NOx limits of the era.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
 

1gibson (Mechanical)
3 May 12 12:29
I've always thought there was something to increased mass flow through a turbo due to addition of water injection. May positively impact intake/exhaust pressure ratio, because the turbo can perform the same or more work (additional energy from mass flow) at the same or lower pre-turbo exhaust pressure.

I also have this vague concept that a cylinder charge including some steam, could be slightly less compressible than cylinder charge that does not, assuming equal cylinder pressure. Which may favor increase torque?

Now, somebody correct me? :)
140Airpower (Automotive)
3 May 12 13:28
dgallup, an intercooler dumps compression heat, energy, into the atmosphere. It is a heat, energy, sink.
There is no question an intercooler is normally highly beneficial to the operation of engines. This is due mainly to combustion characteristics and operating points. In particular, decreasing charge temperature in supercharged or NA engines allows a higher total compression, from supercharging plus static CR, without detonation, a fuel issue. That generally increases thermal efficiency. This does not change the fact that an intercooler is an energy sink.
A motoring cycle, where the supercharged engine is run at speed without ignition, takes more energy with an intercooler in place partly because of the restriction it poses and mostly because the lost compression heat returns less energy on the expansion stroke.
Did you do any motoring cycles? This is normally not of interest.
 
winfieldblue (Automotive)
3 May 12 18:45
140Airpower, I would have thought that a cylinder filled with a larger mass of air would have more expansion given the same amount of fuel/btu's. The compression ratio would be higher with cooler air.....and that would explain why my idi diesel engine suffers a large power loss when breathing pre-heated intake air!
hemi (Automotive)
3 May 12 19:05

Quote (140airpower):

BTW, the earliest turbo auto engines were the Oldsmobile Jetfire (not buick) and Corvair Monza Spyder of 1962, 12 years before Porsche.
  Yes, those were the two I had in mind, I mistakenly wrote Buick since the Olds 215 was simply a derivative of the Buick 215.  Thanks for pointing that out.
I guess our common ground is that the early (2nd gen, 70's) auto turbo applications I was alluding to (turbo Trans Am, Buick Regal, Ford 2.3 e.g.) were attempts at economical performance, not economy cars per se, which is all I was trying to say.
hemi (Automotive)
3 May 12 19:08

Quote (winfieldblue (Automotive)     
3 May 12 18:45):


140Airpower, I would have thought that a cylinder filled with a larger mass of air would have more expansion given the same amount of fuel/btu's. The compression ratio would be higher with cooler air.....and that would explain why my idi diesel engine suffers a large power loss when breathing pre-heated intake air!

winfieldblue, can you give us the P-V and T-S diagrams for that?
140Airpower (Automotive)
3 May 12 19:35
1gibson, water, H2O, is a lighter molecule than either nitrogen, N2, or oxygen, O2. To the extent that water vapor replaces air, the charge becomes lighter by mass. Furthermore, the replacement of an amount of air by water vapor lowers power by that exact amount.

The mechanisms by which water helps have been measured, calculated, surmised and speculated on by many authors.
From what I can tell....
The benefit of water as a VAPOR is that by replacing some air it lowers combustion pressure from charge dilution. At high enough temperatures its specific heat increases above that of the burned and unburned parts of the charge, thus reducing temperature and pressure and it also begins to dissociate, absorbing even more heat. The presence of water vapor then tends to slow the burn and reduce the peak temperatures and pressures. It is a good anti-knock agent with any and all fuels in an SI engine. It has somewhat different beneficial effects in diesel engines and jet engines.

Water introduced as a LIQUID, sprayed into the manifold or direct injected, will absorb a LOT of heat from its very high heat of vaporization. In the manifold, it will cool the charge air to the extent that it evaporates (charge air has to be hot) and will thereby increase the charge density. What water that does not evaporate in the manifold or if it is direct injected it will retard the temperature and pressure rise on the compression stroke from the heat it absorbs while evaporating and then reduce the maximum temperature and pressure during combustion from the mechanisms described above.
Water is usually measured as a percent of fuel by weight. Popular water injection systems can be set to inject water up to some low value like 25% of fuel. However, I have not seen anything that says there is a limit to how much water can be injected under high boost up to 360%, 3.6 x the amount of fuel by weight direct injected. In WWII 60% of fuel was common and 150% of fuel was documented. The combined anti-knock effects run anywhere from 1.5 to 3 octane numbers, ON, per 10%. One test gave 20 ON for 60%.
Later in the power stroke water returns the energy it has absorbed. In a turbo setup, I believe the return of energy should be greater compared to an open exhaust setup. However, water lowers the thermal efficiency of an engine overall (in terms of BSFC) even while increasing the maximum boost allowable and power output (the figures I've seen on efficiency do not account for the decrease in the required cooling power).
Also, there is a great benefit in mixing 50% Methanol with the water in terms of much better evaporation, cooling and increased charge density in the manifold and therefore more power. The merits of Methanol were discussed before.
140Airpower (Automotive)
3 May 12 19:49
winfielblue, I think you are correct.
140Airpower (Automotive)
3 May 12 20:16
1gibson, I think that thermal efficiency is a tricky thing to measure accurately. BSFC is a standard yardstick since Ricardo's early days, but measurements of BSFC on a dyno can be skewed by such things as coolant temps and whether the engine runs its own water pump and provides its own power for the radiator fan. Heat rejection is a factor and ignition or injection timing, mixture, CR, back pressure, etc come into play. The use of an intercooler is part of the cooling budget. I am well aware of the undeniable advantages, but I wonder about the thermal accounting.
winfieldblue (Automotive)
3 May 12 20:46
Hemi, I have no diagrams for that, I'm trying to figure out why my N.A. idi diesel makes more power with a cooler intake charge while using the same fuel quantity (full throttle). This engine has no computer,so intake air temp doesn't change injection timing or the amount of fuel injected. Where does the extra power come from? 3 possible explanations spring to mind, one being a higher compression ratio from more air density, two being more heat transfer into the cooler combustion air rather than to the cylinder/head/piston,and three I'm wondering if the expansion rate of air is linear in regard to temperature. Any other offerings would be appreciated!  
azmios (Automotive)
9 Oct 12 12:46
Slim,

I think the SAE paper 2009-01-2808 and 2009-32-0047 will shed some light on why water injection makes more power. There are also many gas turbine that use water injection to make more power, lower fuel consumption and reduces NOx.
Slim3 (Automotive) (OP)
10 Oct 12 2:02
Thanks azmios, I will try to find those SAE papers and read them. I am about to finish up my direct injected compressed air starting system on my show car and plan to enter it in the Oct 13th British car show in Nashville.
azmios (Automotive)
10 Oct 12 2:52
Slim, if you go over the paper, water has a high specific heat capacity and latent heat of evaporation. This simply mean that it will absorb a lot of combustion heat thus minimizing the combustion heat from being wasted. Furthermore, the gas constant R for steam is much higher than nitrogen or CO2, at high temperature, the pressure increase is also much bigger than the CO2 or N2 gas expansion.
Compositepro (Chemical)
10 Oct 12 12:48
Er... the gas constant is just that, constant. You are probably referring to the molecular weight effect where one gram of water vapor has more volume than one gram of CO2. However, the effect of temperature and pressure change is the same on both gases.
azmios (Automotive)
10 Oct 12 13:20
Compositepro, Not really, you first have to read the SAE paper. The gas constant R is independent of the molecular weight. The constant R is relevant according to the P=mRT/V. With higher specific heat capacity of water, you will get higher T. Once you plug in that T, the higher R will give you higher P too.
Helpful Member!(2)  hemi (Automotive)
10 Oct 12 18:21
Azmios, water injection, along with other substances and methods of internal cooling, does not inherently increase power. In fact, with no other changes, it does the opposite. The benefit of internal cooling is that it permits more power to be made, due to its various direct effects on physical limitations on maximum power, which are application dependent. The most obvious effect is it reduces local peak temperatures in the combustion chamber and exhaust system. Taking advantage of this effect, the performance engineer can increase the maximum charge flow, gaining net power while not exceeding material temperature limits.
A secondary effect of the cooling is that combustion rates are reduced, which tends to reduce peak pressure. Taking advantage of this, the performance engineer can take steps to move the combustion phasing closer to TDC, or increase the charge flow, gaining net power while not exceeding power cylinder and cranktrain stress limits. In Otto-cycle applications, maximum power is typically knock-limited. Internal cooling typically has a very strong effect on suppressing knock. Taking advantage of this, the performance engineer can re-optimize compression ratio, charge flow, air/fuel ratio, and combustion phasing for substantial gains in net power.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

patprimmer (Publican)
10 Oct 12 19:30
Hemi.

An excellent explanation.

Regards
Pat
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hemi (Automotive)
10 Oct 12 22:13
Thanks Pat. Every once in a while, a blind squirrel finds a nut.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

patprimmer (Publican)
10 Oct 12 22:37
Even if only by bumping into it and hitting his head hard. winky smile

Regards
Pat
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Helpful Member!  azmios (Automotive)
11 Oct 12 6:26
hemi, i think you should rear paper below

"High output supercharging without intercooling: theory and results" by J W G Turner and R J Pearson.

There is also an explanation that Slim is looking for on why the mixture of methanol and water returns better power in Charles Taylor's engine text book.

As for your explanation about water in the combustion chamber not producing any power. I beg to differ because of the paper below: -
1) Lestz, S.J., Melton, R.B. Jr., Rambie, E.J.,“Feasibility of Cooling Diesel Engines by Introducing Water Into the Combustion Chamber,” SAE paper no. 750129, 1975

The paper above is done by the US Army researchers decades ago,the paper will tell you why you're wrong. The power went up a lot when water is present in the combustion chamber.

In case you are not aware, Nasa also published several papers on the use of water injection to achieve extreme thrust in the jet engine. These papers will also tell you that you are really wrong.

I wish that I can tell you a whole lot of other wonderful things that can come with water in combustion chamber of piston and turbine engines, unfortunately for me most of them are classified. There are so many things that people outside of the organizations that do skunkwork under the government funded research projects will never understand. Even if others fail to understand, we dont simply insult them, instead we simply say "ignore him he's not one of us, dont bother to explain".

Anyhow, I bet you wont bother to read all these papers right that I quoted right, so I wont bother to explain any further.
Slim3 (Automotive) (OP)
11 Oct 12 10:42
Thanks again azmios, for the clear explanation. I didn't know why it worked, I just know for sure that it does work and works well from my experiments and practical application. Those in doubt need to actually try it.

Slim3
azmios (Automotive)
11 Oct 12 11:25
Slim3, here is another proof to support your claim

http://www.lotuscars.com/gb/engineering/lotus-exig...
140Airpower (Automotive)
11 Oct 12 15:32
The effects of water introduced in piston engines has been studied since the very early days of the 20th century and comprehensive, complete and definitive answers are not all in hand. Studies are being done to this day. However, of everything I have found, nobody says that water releases energy and produces power and in fact water CANNOT produce power in these types of engines. That is not to say that the ENGINE cannot produce more power with the introduction of water for several reasons. The most obvious reasons have already been mentioned by other posters.
From what I've read, a normally aspirated engine that is performing correctly will suffer a loss of power if water is injected into the manifold. For a supercharged engine there are a variety of results that you can get depending on circumstances and especially if the engine is designed for water injection. Gas turbines are different.
patprimmer (Publican)
11 Oct 12 21:57
azmios.

Unless I really missed something somewhere, if the power from the steam pressure is more than the power absorbed to convert the water to steam, you have an over unity device. ie you just destroyed the classic laws of thermodynamics and can now build a perpetual motion machine that will contribute work to the outside as well as sustaining itself.

Now if we can also turn lead to gold we can control the worlds power and wealth.

Regards
Pat
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Slim3 (Automotive) (OP)
12 Oct 12 1:10
Pat, you mean that you can heat air and get just as much power as heating water and turning it into steam? I didn't know that. Why didn't steam engines just heat the air and not bother with the water? Does heating air give you the same expansion power as turning water to steam?

That still don't explain to this uneducated mind why in my test runs that an injection of 50/50 water/alcohol out performed any other mixture ratio in either direction. And did it in a good 318 Dodge and a worn out 318 Dodge. The company that gave me the injection systems made that claim and I had to test it because I couldn't understand why and I still don't understand it.

Slim3
azmios (Automotive)
12 Oct 12 3:51
140, let's make it simple. Once fuel is ignited, there will be lots of heat released. Heat alone will not move piston or turbine, but expansion of gas will. If I ask my 9 years old son to put down a burning campfire or cool off hot metal quickly, he will not use gas or fan, instead he will use water. Similarly, if I dont absorb the combustion heat in a turbine or piston engine quickly, lots of heat will be absorbed by the metal, coolant and the combustion gases. Once the combustion gases absorb the heat, it will expand and pushes the piston down.

The combustion gases consists mostly of N2 and CO2. Both have low specific heat capacity meaning that it will absorb some heat but it is not the best medium. Let's assume if we can somehow introduce water in the combustion chamber preferably when ignition event is about to end, the water in liquid state will absorb heat, until it reaches the boiling point. Once it boils, it will absorb a lot more heat in order to change its state to gas. Even in gaseous state, the specific heat capacity is still higher than N2 or CO2 thus it will continue to absorb heat until equilibrium is reached.

Once the water turns into steam, you can use the gas constant R to calculate the pressure increase (to move the piston downward) using ideal gas law. This is what those SAE and Nasa technical papers are trying to tell us.

I do agree with your opinion that water does not make power, nothing wrong with this as water is not a fuel. However, water is really helpful in absorbing the combustion heat and to expand to make work. Also, if you read the SAE papers, water can function as an energy carrier in which you can heat up water before it is injected into the combustion chamber. This will speed up the change from liquid state to gaseous state. Check out the work done by Transonic, they use fuel as an energy carrier by heating up the fuel before it is injected into the combustion chamber.
azmios (Automotive)
12 Oct 12 3:58
Pat, I beg to differ. The heat released from fuel is always more than the kinetic energy created after that. How can you have over unity unless someone is blinder than a blind squirrel???

Water in both liquid and gaseous states naturally have very high specific heat capacity meaning that it wont stop absorbing the heat until equilibrium is reached. The hotter the steam becomes, the bigger the gas expansion is. That's I quoted the use of specific heat capacity and gas constant R.

azmios (Automotive)
12 Oct 12 4:23
hemi, where are you? we need to debate further about this water injection as I have all the time to do so.
hydroman247 (Mechanical)
12 Oct 12 4:24
This is extremely interesting. Do you have any articles or research papers you can link us to azmios?

Thanks
azmios (Automotive)
12 Oct 12 4:48
hydroman, scroll through my earlier replies. many of them are available for free, i have included the links
patprimmer (Publican)
12 Oct 12 5:57
There seems to be some misuse of some very technical sounding words here.

I detect an attempt at BS baffles brains type sell job.

Nothing, if it's colder than it's surroundings, no matter what it's specific heat, will stop absorbing heat until equilibrium is reached. That is kinda what equilibrium means and it has nothing to do with specific heat. This is simple high school physics.

Regards
Pat
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azmios (Automotive)
12 Oct 12 10:49
"Nothing, if it's colder than it's surroundings, no matter what it's specific heat, will stop absorbing heat until equilibrium is reached. That is kinda what equilibrium means and it has nothing to do with specific heat."

Heat absorption has a lot to do with specific heat capacity. That's why some rankine cycle uses liquid that has greater specific heat capacity. Also, if you compress water, the specific heat capacity tend to go up and therefore becomes better heat absorber.

You can read all of these in the papers that I listed above. Since these papers are peer reviewed and written by specialists in those areas, I would rather trust these authors than someone who makes a living as a textile engineer and never publish anything in engine journals.
hemi (Automotive)
12 Oct 12 11:20
azmios,

The title and abstract of the SAE 2009-01-2808 paper are as follows:

Feasibility Study of a Novel Combustion Cycle Involving Oxygen and Water
Abstract:
A novel combustion cycle which operates in 2-stroke operation and utilizes a novel exhaust valve timing and lift strategy is proposed to potentially replace the existing Otto and Diesel cycles. Air is replaced with oxygen to maximize the combustion efficiency and to enable broader range of fuels to be used. Water is injected into the combustion chamber to enhance the combustion heat absorption, gas expansion and to function as an energy carrier. Engine secondary heat that will otherwise be wasted to the environment is recovered and reused by the engine. Engine theoretical efficiency and out emissions are predicted to be improved.


I don't need to read the whole paper to recognize that the process described is quite unrelated to water injected conventional cycles. Furthermore, it is a feasibility study only with theoretical results, not proven science; I haven't heard of any practical developents along these lines, have you?

The same comments apply to the other paper you referenced, SAE 2009-32-0047 which is by the same author, I might add.

I could not locate the Turner and Pearson paper on the web.

Would you care to quote the passages from the US Army and NASA papers that state adding water increases power?

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

azmios (Automotive)
12 Oct 12 12:01
Hemi, good to hear from you again. For the US army, read the first section of the conclusion and also the additional expansion in Figure 8 PV diagram. For the nasa paper, try this one "Analysis of Gas Turbine Engines Using Water and Oxygen Injection to Achieve High Mach Numbers and High Thrust" by Hennebery and Snyder.

I have with me the paper from Turner and Pearson, not sure whether you can get the softcopy for free.

As for the 2009-01-2808, the proposed concept is too complex and if you attend the previous SAE congress, many of what proposed in the paper are broken down into sub areas, like oxygen combustion, heat recovery, 2 stroke with poppet valve, etc. If you combine all these smaller researches, we may get something closer to what proposed in the paper.
hemi (Automotive)
12 Oct 12 14:50
I read the NASA paper, and apart from the fact that the heat engine cycle they are investigating is drastically different from that of a reciprocating engine, I did not see any claim that adding water directly increased power, only that adding water allowed more power to be made. The analyses that are presented show trajectories of hypothetical engines with water injection proceeding through their missions, but do not include any comparisons of a given operating point, with water injection manipulated as an independent variable at otherwise constant conditions. So, unless there's something I missed, nothing in this paper supports your claim.
It's difficult to understand what is prompting you to peruse these esoteric studies of hypothetical engines and draw conclusions about how water injection affects traditional reciprocating engines, that are not supported by the past 70 years of research, development, and established practice.

FYI, I have no personal incentive to pay the $16 price for the copyrighted SAE papers you reference. I assume you have copies of your own, and it would be considered "fair use" if you would quote here the passages that you say support your argument.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

140Airpower (Automotive)
12 Oct 12 17:47
azmios, the descriptions and diagrams of this engine show, as hemi stated, a type of power plant drastically different from standard internal combustion engines. Hence I would not expect that the use of water in the combustion chamber here relates well to water injection in general.
There are a couple of things that raise questions of standard meanings, especially his use of the term "gas constant, R". In science the universal gas constant is given in units of moles, not kg. It is the same for all gasses, not different for each one. So, I'm not sure if there could be other alternative uses of standard nomenclature.
Key features that distinguish this power plant from the standard internal combustion engines are the use of consumables the normal IC engine does not use, pure oxygen and apparently large quantities of water. For that, there is a mobile oxygen generator. Note that the overall efficiency of this engine will depend multiplicatively on the efficiency of that generator, so that if it is 50% efficient, the overall efficiency is only 50% of whatever is the efficiency of the rest of the engine. I think this is a fatal disadvantage.
The use of water appears to be in a "steam engine" mode which is inferior to the simple gas expansion of the IC engine except that the use of water this way can cool the engine without need of any cooling system and it can capture more of the heat of combustion. This is a bottom cycle phase that normally is not worth pursuing in a mobile powerplant, especially since it consumes significant quantities of water that has to be carried or recondensed (involving more weight, space and complexity).
I think this engine could be best suited to a large, stationary application and will require development to prove itself.

It is hard to beat the familiar IC engine for light-weight, reasonably cheap and efficient mobile power. It does not have to carry 1/2 of its reactive material (air) and carries none of its waste product. The fuel is completely consumed and the fuel container weighs almost nothing. Beating its efficiency by a marginal amount is not likely to be worth the trouble if it involves extra complexity.
azmios (Automotive)
12 Oct 12 17:51
hemi,

I will quote something from Turner's paper once I am back in the office on monday.

The nasa paper is different from a piston engine. However, if we look at it from the point of view of heat engine, there is not much different, there is compression, ignition and expansion. I know that many believes that higher compression ratio makes more power. However, it is the expansion ratio which is more important than the CR. In this context, expansion of steam moves the piston in piston engine. In case of jet engine, the pressure increase provides thrust for the propulsion system.

I agreed with your explanation earlier but much like what slim3 is believing, the power increases is somehow more than what can be achieved from just extending the knock limit. This is the reason why the water injection's benefit is actually beyond what the conventional thinking in the conventional engine. Turner's paper didnt touch much of the scientific reason on why the power increases too.

You're right in saying that the 2009-01-2808 is just theoretical study. I am interested to see how the theoretical points brought up in the can be disputed. You should try challenging the study made in that paper.
140Airpower (Automotive)
12 Oct 12 18:50
azmios, your statement, "I am interested to see how the theoretical points brought up in the can be disputed. You should try challenging the study made in that paper", turns the situation on its head. It is not for anyone to "challenge" assertions made in a paper. It is for you or the author to demonstrate and prove that the exceptional claims made can be realized. Everyone else should have a healthy skepticism. This is the way science is done.
azmios (Automotive)
13 Oct 12 4:38
air,

gas constant R does not have any unit. just flip the thermodynamics books.

the efficiency of oxygen generator is high. coal power plants in china are already using PSA generator to get oxygen. they get intense flame from coal that is much cleaner if compared to air.

also you should check marine engines from europe that are already injecting water. they made many benefit claims with their system.

you may say that nothing beats the conventional piston engine. at less than 50% efficient, there is nothing worth to shout about. there is still big radiator required and the exhaust gas is still hot. i use these two factors to estimate the efficiency of the engine.

as for the sae paper, what is wrong in proving that the claims made to be wrong? i am a reviewer of many engine and combustion journals and i would normally point out a small point to trigger the authors in making better explanation, clarifications or amendment. the papers normally turn out to be a great ones
patprimmer (Publican)
13 Oct 12 12:58
azmios

Instead of quoting NASA papers on jet engines look back a bit further and quote NACA papers on WW11 supercharged piston engines. There is quite a large collection that have actually been studied by a lowly textiles engineer that just may have opened a book or two in other areas over the last 40 odd years.

I can't remember who claimed the use of steam engines proves that water expands with more pressure for the same heat input than does air.

Steam is used as the source of heat is external and large boilers and fires can make a lot of heat. They went out of vogue because the IC was overall more efficient.

Equilibrium and heat transfer is well explained in the zeroth law of thermodynamics. Even a lowly textiles engineer knows that.

Specific heat is to do with the amount of heat required to heat a certain mass a certain amount, not to do with equilibrium.

Regards
Pat
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azmios (Automotive)
13 Oct 12 17:53
hi pat,

Agreed with you, the British and Germans injected methanol+water in their supercharger engines during take off. This is covered in Charles Taylor's text book.

If you flip through MTZ about 8 years ago, German government funded a research to compare the steam engine and IC engine. IC engine won without any doubt. What's never been done is the hybrid between IC and steam engine. This should give you the best of both worlds. Imagine the steam expansion magnitude if it is in direct heat transfer with the heat source rather than being externally heated like in the traditional steam engine.

If given a choice between water having specific heat capacity at 4.18 or 6.8. Anytime I would take the 6.8, but this can only be achieved if the water is compressed. Higher specific heat capacity will absorb heat faster from the heat source.
hemi (Automotive)
13 Oct 12 17:54
"gas constant R does not have any unit"

come again?!!

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

azmios (Automotive)
13 Oct 12 18:33
hemi,

Sorry for that, the unit is kJ/kg*K.
KeithDyer (Industrial)
14 Oct 12 7:01
For what it's worth . . . . . . . . ,

Back in the late 70's and early 80's, I built engines and was crew for the premier Drag Boat Racer of that era, Eddie Hill.

We held all four drag boat association ET and MPH records at the same time, bests of 5.60's at 226 / 229 MPH. Exceptional win percentage, the boat to beat anywhere we ran it.

Typical Keith Black 500" Aluminum Chrysler Nitro Hemi just like all of the Top Fuel / Funny Car engines of the day. 14-71 blower making about 30 - 32 psi on a pass. We ran a HIGH percentage of Nitromethane (about 96-97%), with a crude water injection in place. We used the blower pressure from the intake manifold and ran it to a small Moon tank to move the water to nozzles above the fuel injector butterflies. The harder the pass, the more water that was delivered to the engine. Average water consumption was 1.1 / 1.2 liters per pass.

We used this method to primarily keep from having to tear the engine down between runs as we had little money to spend on parts and a small crew to perform such maintenance like all of the other teams. The same guys that were detonating the guts out of their engines every time down the track.

This system did what we needed it to do at the time. Once at Bakersfield (Lake Ming) we tried to use methanol in the system instead of water. Huge fireball at half track!! Like all hot rod guys, trying to get a little more out of the engine!!

Not real scientific, but effective enough to keep us racing up front and continuing to dominate the sport until Ed's violent crash at Firebird (Phoenix) in 1984.

Like I said up front, "FWIW"!!

Take care, K
140Airpower (Automotive)
14 Oct 12 11:56
Keith, what it's worth is a lot. It is the most convincing account the I've heard of how effective water injection is at reducing mechanical loads on parts as well as reducing heat.
Helpful Member!  140Airpower (Automotive)
14 Oct 12 12:03
azmios, Your remark about textile engineers implies there is some flaw in that that lessens the value of an engineer’s opinions. This borders on a personal attack. One quality in a good engineer of any specialty is the ability to spot BS. Virtually all the contributors here appear to be giving their honest opinions and do not appear to be promoting scams.

You said the oxygen generator is of “high” efficiency. Of course anything less than 100% will diminish the overall efficiency of the engine. What is “high” in your estimate?
Oxygen from the air is free. Oxygen that has to be generated comes with a cost: a cost in energy, a cost in machinery and a cost in some starting material. There are only a few choices that come to mind. One is electrolysis of water. At least the starting material is cheap, but the efficiency of this is NEGATIVE. It costs more energy to do the electrolysis than you can get back by combining the oxygen and hydrogen with each other and even worse when you combine them with other reactants. Here we would be talking about using only the oxygen? A very big loser! Another method is to extract oxygen from some oxygen rich compound. The usual favorite is CONCENTRATED hydrogen peroxide. This material is relatively expensive, unstable and dangerous. At least the water is built-in. There are other compounds, but the best are also expensive, unstable and dangerous. A third method of providing oxygen is to use compressed oxygen gas in cylinders. I think the image of that speaks for itself. What method is proposed? It needs to provide oxygen at a high rate and have an overall total cost that is only marginally more than the cost of air. In my opinion, an oxygen generator like that is a much, much bigger and more important innovation than this proposed engine design.

Combining a steam engine with an IC engine is an very old idea. It’s obvious that you could boil water using exhaust heat and run a steam motor, extracting some additional energy from the fuel, increasing overall efficiency. Injecting water directly into the IC engine can also be done. The thermodynamic balance is questionable with respect to the amount of steam expansion compared to the reduced exhaust gas expansion. But there is no question that less heat is lost to the cooling system. Injecting water at any time during the burn will reduce NOx, but will increase HCs. It will also likely reduce the effectiveness of a catalytic converter due to greatly diminished exhaust temperature. It is also most problematic for lean-burn cruise where the effect of causing misfire (if injected early or in the intake tract) and of quenching the flame exacerbates the emissions problem and hurts efficiency.
Injecting water after the burn can be done. The steam expansion is now mostly in the exhaust tract and can be utilized by a bottom cycle motor like a turbocharger. The efficiency of this is not as good as a piston motor.
A very interesting use of the steam engine principle is the Crower 6-stroke engine. An extra crank rotation is used where water is sprayed into the hot cylinder after the normal 4-stroke cycle. The water extracts heat from the metal, cools the engine sufficiently to obviate the need of a cooling system, expands as steam, -applying pressure to the piston and adding torque to the crank. This is a pure plus for efficiency with virtually no effect on the normal burn and at the cost of very little extra mechanism. It will affect the catalytic converter, however.
The big problem for a mobile powerplant with bottom cycle engines that I can see is that they cannot be very efficient themselves because they are working with a greatly diminished starting temperature compared to the IC initial temperature AND they usually comprise a mechanism, like a steam motor, that is comparable to (maybe ¼ to ½) the mass and complexity of the IC engine. For example, the Crower 6-stroke adds a crank rotation to extract a small amount of power. So a 3 liter Crower is like an extra large and heavy 2 liter IC engine that is perhaps 10% more efficient. This is probably not a good trade off for a car engine even counting not needing much of, if any, cooling system. Steam engines like this also require that you carry water. I don’t believe a recondensing systems in a car makes a lot of sense. The amount of water the Crower would use needs to be about equal to or more than the amount of fuel by weight. So, when you get 10 gal of gas, you need at least 7 gal of water.

All the negative observations that apply to a mobile application do not necessarily apply to a stationary plant. In fact, even the oxygen generator problem could be very different in a stationary plant.
azmios (Automotive)
14 Oct 12 13:48
Air,

It's good that you made some comment about the personal attack. I hope that people who earlier wrote about the "blind squirrel" and accusing people with BS will take notice. Frankly I dont enjoy much responding to other people's personal attack but if it is necessary to make others realize, it should be justified. If you personally feel that I am scamming here, all it needs to prove so is to debate about the points that I brought up rather than just accusing others of scamming. it is so much easier to accuse others rather than to counter the so called scams with facts and figures.

Back to the debates. The idea of using oxygen to replace air is not new, there are many papers in public domain involving both piston and turbine engines. That 2009-01-2808 made a lot of references to submarine engine researches. French and Japanese engineers are still active pursuing the oxygen engine.

I know that many will think that why burn oxygen when we have air at no cost? Similarly, I can ask them why do we have to compress air that contains 78% (volumetric) nitrogen? The work needed to compress air up to 100 bar in diesel requires a lot of energy, furthermore, many diesel engine run lean thus the amount of air compressed is even more. Compressing this much of air up to 100 bar requires more energy than what it takes to generate oxygen from air. I personally feel that nitrogen does not belong in the combustion chamber. Water is a better heat absorber and gas expander.

As pointed out in that SAE paper, raising the cylinder temperature is best done by retaining some of the hot residual gases from the previous cycle. the compression work on the other hand is needed just to further raise the temperature slightly above what is needed for optimum fuel auto ignition to occur. When this happens, the work needed to raise the cylinder temperature is much lesser and the freed energy can be used to generate oxygen using PSA generator.

As proven by the coal power plants in China, the use of oxygen gives them advantage in terms of energy. Rather than having to spend a lot of energy to process the coal into something cleaner, the use of oxygen ensures that most of the complex hydrocarbon chain is broken and oxidized releasing intense heat. The irony is that, decades ago many american researchers have proven that the use of air with more than 21% oxygen content have enabled them to burn low quality fuel oil cleanly. Since not many read about the findings, many still feels that it is better to spend a lot of energy to process raw crude oil into clean fuel rather than to use oxygen to burn less refined fuels.


Slim3 (Automotive) (OP)
14 Oct 12 14:19
I have a question for all of you as I have no engineering degree and ask it out of practical applications.

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power. Since we were getting much higher temperature and thus gas expansion, why did we receive lower power form it?

I know that when you adjust the fuel mixture leaner then stoichiometric, horse power goes down and temperature in the combustion chamber goes up. And when you adjust the mixture richer then stoichiometric, (as much as 30% richer) horse power goes up and combustion chamber temperature goes down. And according to papers I read from Champion Spark Plugs and from Ford Motor Co. the flame front is completely across the combustion chamber by from 15 degrees to 30 degrees depending on the engine design, mixture etc. And when the piston to rod to crankshaft is at 79 to 80 degrees crank, leverage is at it's best and piston velocity is at it's highest. I know that even though the flame front may be across the combustion chamber, there is still a continuing burn and a long process of expansion.

Without changing the fuel mixture at all and not advancing ignition timing at all to take advantage of any octane rate increase due to my added injection of 50/50 water/ethanol alcohol, why did I receive much additional power on two different engines that I tried it on? I know it was not a fluke as I made dozens of test runs all day long on the two vehicles.

I believed at the time it was a combination of vaporization in the intake manifold giving a lower intake temperature due to the high latent heat of vaporization of the alcohol, thus a more dense air charge going in and even though the combustion chamber temperatures were lowered too, I gained some power from the steam produced and the added combustion of the alcohol which contains a small portion of it's own oxygen necessary for it's own combustion.

In the late 70's I came to the conclusion that the Otto piston engine is not making good use of combustion other then trapping most of it in a chamber. So I am now experimenting with alternate geometry designs of a piston engine to attempt to make better use of combustion pressures.

Slim3

azmios (Automotive)
14 Oct 12 15:25
"Without changing the fuel mixture at all and not advancing ignition timing at all to take advantage of any octane rate increase due to my added injection of 50/50 water/ethanol alcohol, why did I receive much additional power on two different engines that I tried it on? I know it was not a fluke as I made dozens of test runs all day long on the two vehicles."

The first line of your sentence is the key to the question that you and I have been asking. As per my earlier reply, the phenomena has not been scientifically explained on why such power increases.
winfieldblue (Automotive)
14 Oct 12 16:35
Experimenting with used cooking oil gave me a few surprises, boiling off any water present in the oil after the filtering process resulted in a lower power output from the engine ,nothing startling but easily noticeable, I then realised that the worst thing to do when your frying pan catches on fire is to throw water onto it while attempting to put the flames out, if you've never tried this, oil sprays out in all directions spreading the flame with it. I don't know what happens when water is thrown onto a petrol fueled fire, but I think that much the same effect would be created, obviously that's why we have different fire extinguishers for liquid fires-water doesn't work well at all when trying to extinguish the flame!. A faster more complete burn would be more easily noticed in a large open hemi type chamber, maybe that's where some of your power increase came from Slim3!
patprimmer (Publican)
14 Oct 12 20:34
slim3

by adding alcohol via the 50/50 mix, you made the mixture richer so the a:f was in fact changed unless you corrected for that and removed fuel from the main source.

Also increasing the amount of liquid entering the chamber, you effectively increase CR until the liquid evaporates. When it evaporates, you lose pressure from the loss of heat temperature going to supply latent heat of vaporisation, but you gain pressure from more gas molecules present.

You can't add energy to the closed system, so any pressure has to come from heat generated from a chemical reaction such as burning fuel or from latent energy from a change of state. The only change of state here is from liquid to gas which absorbs heat. It does not generate heat.

For further study, look up the gas laws and the laws of thermodynamics and latent heat.

Don't confuse temperature and heat, they are different.

Also, lean mixture does not increase chamber temperature, it increases exhaust temperature as it burns slower and more heat is generated later in the cycle.

To burn fuel in air, you need molecules of air and fuel aligned and enough heat there to trigger the reaction. Even though we try to mix air and fuel perfectly, even a very small well atomised drop of liquid fuel contains problably thousands of molecules or even millions of molecules. Also they are not perfectly distributed throughout the chamber so there will always be some oxygen molecules not close enough to some fuel molecules to burn.

For maximum economy we need to burn all the fuel, so we add air to increase the number of oxygen molecules potentially available to the fuel molecules so we burn as much of the fuel in the chamber as possible.

For maximum power we use an excess of fuel so that we burn as much of the oxygen available as possible.

There are limits where you get into diminishing returns re availability of molecules aligned close enough to react vs dilution with other non reacting molecules and coolants that then cause misfires or plug fouling if rich or erosion of metals from the chamber, like valves, pistons or earth straps on the plugs if lean.

Regards
Pat
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patprimmer (Publican)
14 Oct 12 20:44

Quote (slim3)

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power. Since we were getting much higher temperature and thus gas expansion, why did we receive lower power form it?

Further to the above.

As well as higher compression and more NOx, the reduced power comes from compromises to ignition and cam timing and EGR and often from changes to chamber design to open chamber with no quench to reduce hydrocarbons in the exhaust. This reduced quench also resulted in reduced squish so less turbulence across the flame kernel at neat TDC so a slower burn with more heat produced to late where it does less work so is hotter as it goes out the exhaust rather than hotter at TDC and just after.

Regards
Pat
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patprimmer (Publican)
14 Oct 12 21:10
slim3
The combustion chamber is a very dynamic place and while the combined gas laws relate temperature and volume, it takes time to stabilise, so in fact we have higher and lower pressure and temperature areas constantly changing as the engine runs.

Ideally an engine should produce peak cylinder pressure about 12 deg ATDC. If the spark was say 30 deg BTDC, think how long that 42 deg takes at say 6000rpm.

Think about how long it takes the fuel droplets to evaporate and for the molecules to mingle and align with oxygen in air and exhaust and whatever else is in there.

The burning is releasing heat and generating temperature and pressure while evaporation is absorbing heat and reducing temperature and pressure but increasing volume which increases temperature and pressure.

At the same time the piston is moving which changes volume and therefore temperature and pressure.

It is exceptionally complex and dynamic.

Regards
Pat
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patprimmer (Publican)
14 Oct 12 22:09

Quote (azmios)

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power. Since we were getting much higher temperature and thus gas expansion, why did we receive lower power form it?

For one no one called you a blind squirrel. Hemi implied he could find something even if HE was a blind squirrel.

No one said you yourself where BS. I implied some of your statements where based on BS due to your incorrect interpretation of some terms. I stick by that. I even wonder if English is your first language as you seem to have some problems with the meanings of some words. Statements based on wrong meanings of words are inherently inaccurate which is commonly known as BS. If you wish to make statements based on errors and not be called on it, then you are in the wrong site.

Air, I have no problem with someone resorting to personal attack as it is evidence that they have run out of valid argument and it is a last desperate attempt at rebuttal without actually offering any credible evidence.

Regards
Pat
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patprimmer (Publican)
14 Oct 12 22:32
Opps

A quote got pasted into the wrong post with a wrong attribution.

Obviously the quote attributed to azmios should be attributed to slim3 and applied to the post above.

Regards
Pat
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patprimmer (Publican)
14 Oct 12 22:41
Back to the steam engine analogy, the issue with air instead of steam is the volume change.

A tonne of water occupies a lot less space than a tonne of steam, and when kept under enough pressure for the temperature it is heated to, can remain in liquid highly compacted form until released to drive the engine.

Unless air is liquified, the heater unit containing enough air in a closed system to do the work of a tonne of water would pretty much take up a city block at many stories high rather than easily fit into a small pick up truck.

Remember, while the system is pressurised, no more water or air can be added without depressurising first. At least not without an extra pump that also takes power to drive.

Regards
Pat
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Slim3 (Automotive) (OP)
15 Oct 12 3:48
Pat, doesn't that confirm my tests on my straight 170 proof ethanol engine maintaining power with 15% content of water when compared to that same engine tests running on 200 proof?

With my 170 proof I had lost 15% of my fuel and using water to replace that 15% should have lost some heat vaporizing the water. This should have caused me to loose power but many 1/4 mile acceleration test runs showed the same between the 170 proof and the 200 proof ethanol.

Everything I did was real world and none of it came out of a book. True I didn't fully understand why I received some of the results that I did and I am only in here looking for answers.

You are correct that my English is not that great but it is because I have less then a high school education. But it was all American if that is important to you. As far as BS, my guess as to why I was receiving the results I did could have been thought of as BS but everything I did was done as I stated.
And don't worry about hurting my feelings as I use to race motorcycles professionally, spent two years in the US Army as an infantryman in a foreign country and 50+ years in the auto industry and built more high performance engines then most people have even seen. Don't worry about hurting my feelings as you can't. Not sure any one can any more as this old hide has long ago become rather thick and hard.

I'm just looking for real answers.

Slim3
patprimmer (Publican)
15 Oct 12 5:14
Slim

The BS and English second language was not aimed at you.

Azmios claimed his slight as to the lower value of my degree and therefore opinion was a retaliation for the term blind squirrel being used and me calling some of his post BS. I was offering a rebuttal to that. Seeing as how I never even made the blind squirrel comment and as how the hemi who did make it was actually referring to himself, and some very unusual interpretations of some terms used in physics, I was wondering about his language skills. Innuendo and other figurative speech often mistranslates badly. Technical language also sometimes translates badly.

Regards
Pat
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azmios (Automotive)
15 Oct 12 7:03
pat, i feel sorry for you. I guess when people bring machine guns to a technical debate with the intention to shoot people that do not share the same opinions or belief as you do, other innocent bystanders tend to get hurt. Even people with the honest intention to debate will tend to fight back with their bare hands when being shot at. I do not know you and before I join this debate I had nothing against you. You're right, my english is not good and though I speak several languages, english is not my main one. Let's move on to the debate as I am interested to exchange information.

The beauty of water is that as what you pointed out, we can use it when it is needed. It can easily be manipulated using pressure and temperature to exist either in liquid or gaseous state. It should stay in liquid state so that it can absorb heat and carry it elsewhere. It should be turned into gaseous state to extract some kinetic energy from it. If logistic is an issue, we can even condense it and filter it for reuse. Piston engine has a lot of limitations in terms of expansion ratio but if we use gas turbine, we can increase the expansion ratio to really bring down the gases and steam temperatures. The lower the exhaust gas temperature, the easier to condense the steam for reuse.
azmios (Automotive)
15 Oct 12 8:11
Pat,

"Remember, while the system is pressurised, no more water or air can be added without depressurising first. At least not without an extra pump that also takes power to drive. "

typical DI injector injects at 150-200 bar. Water is best to be injected when the intense heat release is ongoing. Furthermore, water at 150-200 bar has its boiling point raised so it can first be heated using coolant heat and later exhaust heat. At Q=mcT, the energy being brought into the combustion chamber will easily pay up for the pump energy consumption.
patprimmer (Publican)
15 Oct 12 8:13
And yet another slight.

And yet another reversal of the laws of thermodynamics.

And yet another off topic post switching to turbine when the subject is spark ignition, Otto cycle, automotive application.

Now back on topic sans BS

slim3

One aspect barely mentioned here that might explain your result.

I don't have the data at hand, but I remember reading somewhere, probably in an NACA report that water is one of the few liquids where when it evaporates into air, the gas produced does not fully compensate for the loss in volume of the air in the system due to the heat absorbed.

For alcohol, although it absorbs heat also as it evaporates, it displaces more air than the cooling compensates for. That is why alcohol fuel racing classes use down nozzles.

That means that if water evaporates in the manifold VE improves as the increase in air density from temperature drop is greater than the air displaced by the water vapour.

If alcohol evaporates in the manifold the cooling is not enough to compensate for the air displaced by the alcohol vapours so VE decreases.

If all other things remain equal (which they never do in the real world) the extra water will increase the VE due to extra charge cooling in the manifold. The improved VE could explain your results.

Regards
Pat
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azmios (Automotive)
15 Oct 12 8:14
Air,

"Injecting water after the burn can be done. The steam expansion is now mostly in the exhaust tract and can be utilized by a bottom cycle motor like a turbocharger. The efficiency of this is not as good as a piston motor."

It all depends, I am inclined to have water to be injected upward into the combustion chamber. This way, superheated water can be introduced into the combustion chamber right after the TDC without suppressing the fuel development in the piston bowl.
Helpful Member!(2)  azmios (Automotive)
15 Oct 12 8:20
Slim3,

Our questions about the link between water+methanol and power have not been answered yet. Will it be possible for you to measure the exhaust gas temperature right after the exhaust port. If we can compare the exhaust temperature with and without the water injection, it will shed some light into this. I am expecting that the exhaust temperature to be decreased significantly when it involves water injection. If drop in exhaust gas is detected, theoretically, the heat energy has to go somewhere and if it doesnt end up as coolant or exhaust heat, it has to make more power at the crankshaft.

Furthermore, the combustion of methanol will have more water after the combustion. This water will also help in the heat absorption and gas expansion processes.


patprimmer (Publican)
15 Oct 12 8:31
azmio

If the water enters the chamber in liquid phase and exits the exhaust in gas phase, surely some energy is lost out the exhaust in the form of latent heat of vaporisation.

Regards
Pat
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azmios (Automotive)
15 Oct 12 9:01
pat, i see it differently. The reward in gas expansion is the reward to a small price that we have to pay in the form of latent heat of evaporation. After all, the process is reversible. You cant do the same with combustion process, once it happens, it is not reversible.
patprimmer (Publican)
15 Oct 12 9:26
So what. The latent heat of vaporisation which is significant just gets blown out the exhaust. If it is then reversed by giving heat to the surrounding air. That has no influence on what happens in the chamber.

Regards
Pat
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azmios (Automotive)
15 Oct 12 9:45
not really, even when the steam is blown out through the exhaust gas, it can be recovered through a condenser and there is significant amount of thermal energy that can be recovered and reintroduced into the combustion chamber.
patprimmer (Publican)
15 Oct 12 10:07
slim

Did you have a condenser and recirculate the energy recovered from the exhaust.

Azmio

I am interested to know just how you get this energy back into the Otto cycle 4 stroke automotive engine which is the engine type in question.

Regards
Pat
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140Airpower (Automotive)
15 Oct 12 10:30
azmios, You complain that no one has tried "this" and there isn't any information on "that", but in reality, people have tried virtually everything we are talking about and there are tons of information about what they have found. You have to do the research. You need to see it for yourself because you are not accepting what is being said here.
There are contradictions in things you have proposed. For example, you thought a benefit of injecting water was as a coolant, now you want to preheat the water. The idea of using pure oxygen was to get a more intense burn, but a consequence of a hotter, faster burn is a very significant reduction in the effective octane number of the fuel mixture. This is anathema for a spark ignition engine. You propose having a cumbersome, power hungry oxygen generator and a steam condenser for an automotive application where these things are handicaps. Your ideas are all over the map and don't make good sense.
thruthefence (Aerospace)
15 Oct 12 10:41
A perfect "Steampunk" construct, possibly powering a wrought iron dirigible!
azmios (Automotive)
15 Oct 12 10:48
pat, if you inject water in the combustion chamber at 50C compared to 25C. It will take lesser heat to get another 50C and turn it into steam to make work. Theoretically any secondary heat source that can be used to increase the water temperature is now valuable.
azmios (Automotive)
15 Oct 12 10:53
Air, why does it have to be related to me and my flaw in character? Cant we just stick to the points in this debate?

While many have tried injecting methanol+air in real life, has anyone came up with convincing scientific reasoning to answer the questions that myself and Slim3 are asking? I never said that no work or researches have been done, it is just the scientific reasoning that is lacking and this is what I am seeking at this moment.

By the way, I am now proposing things all over the map. I am just highlighting what have been discussed by the author in the SAE paper 2009-01-2808. Have you read it and fully understood all the points?
Helpful Member!  Tmoose (Mechanical)
15 Oct 12 11:23
Slim3 (Automotive) (OP)
15 Oct 12 12:05
Pat & Azmios,
I did not have a condenser on either the alcohol engine nor on the two Dodge 318 engines. But the thought did cross my mind and on a third engine that only made it on the drawing board I did consider it. I wanted to build a small SI engine the run two cylinders on gasoline slightly richer then stoichiometric and put a heat exchanger with internal spray nozzles using water to make steam and storing the steam for a small on board two stage piston engine to add what power could be obtained via a simplex drive system. Then at the heat exchanger add whatever flame trap I could design to be sure to put the fire out in the exhaust of the two gasoline cylinders which should produce a hot but no fire exhaust gas that is very dirty with a lot of HC. I then intended to inject ethanol alcohol into the exhaust gas to further cool and contract the exhaust gas which would be routed to another cylinder in an attempt to get a second combustion. Then have my heat exchanger on that exhaust port also to attempt to gain more steam for the small on-board steam engine. The end result would be a small four cylinder engine with two cylinders on gasoline and two on dirty exhaust of the first two with alcohol added to bring that exhaust up to a combustible mixture and all four having a heat exchanger producing steam for a small two stage steam engine adding power to the small 4 cylinder engine. The balance of all of this would get upset as soon as I moved the throttle so I would use it as a single speed set at wide open throttle to power a generator to keep a battery pack charged for a electric car. A friend was in on the designing and I tried to show this to Nissan in 1979 but they didn't want to look at it. I got the same response from GM and even Jack Roush. However, in doing the research on alcohol for the project (we both knew a little about alcohol as a racing fuel) I accidentally received a grant form the DOE to build a still and modify an engine to run on straight ethanol. So I got side tracked into an alcohol engine sponsored by the US DOE and that netted me the alcohol/water injection systems which I put to use on two dodge trucks. Briggs and Stratton also sent me a small gasoline engine to play with which I set up as a small dyno with EGT and head temp and dual fuel to measure different mixtures of both fuels, alcohols and gasoline. So here I am still looking for answers. Some of this research lead me to think of direct injected compressed air to start an engine which I did complete and just entered the car in an show this last Saturday. (Olds 215 engine in an MG) Got 3rd place in class probably because of the unique direct injected compressed air start system.
Slim3
hemi (Automotive)
15 Oct 12 14:00


The figure above is from NACA research memorandum E6106, which investigated methods of reducing peak cylinder head temperature in cylinder 10 of a Wright R-2800-21, which would otherwise exceed the manufacturer's specified limit at military power, as installed in a P-47G aircraft. One of the methods investigated was injecting water/ethanol into the intake pipe of cylinder 10. At the top of the figure, the effect of coolant injection rate (on the x-axis) on net BHP is shown. The BHP indicated is for the entire engine, so the changes in power are due to changes in cylinder 10 only, as operating conditions for the other cylinder were held constant. It can be seen that as coolant injection rate increased from 0 to 40lb/hr, cylinder 10 power decreased 30BHP. Assuming cylinder 10 was contributing an equal share of net power with zero coolant injection, this is a reduction of about 35%.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

hemi (Automotive)
15 Oct 12 14:25
Pat wrote:
"I don't have the data at hand, but I remember reading somewhere, probably in an NACA report that water is one of the few liquids where when it evaporates into air, the gas produced does not fully compensate for the loss in volume of the air in the system due to the heat absorbed."

How about this one:

NACA Report 756 Figure 6



Effective charge air density is shown at the top of the figure, for different [injected] water-to-fuel ratios, and as a function of fuel/air ratio. If the image quality raises ambiguity about the symbols, the air density shows a monotonic increase with increased water-to-fuel ratio.
The curves for IMEP at the bottom of the figure are interesting also. While the effect of water injection between 0.06 and 0.09 fuel/air ratio doesn't appear to be significant, the data above 0.10 fuel/air ratio clearly show a monotonic decrease in IMEP with increasing water-to-fuel ratio.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

Helpful Member!  patprimmer (Publican)
15 Oct 12 20:20
azmio

If you cannot see the inconsistencies and lack of fact in your arguments then either you are not an engineer or you have some other problem.

Every single real working engineer here most with professional qualifications disagrees with you. Do you wonder why.

slim.

I knew you did not have a condenser as it was an idiotic suggestion and you are obviously far from idiotic. Your only limitation in this debate is a lack of education which you came here to rectify.

Unfortunately you thread has been hijacked by someone who is on a major misinformation propagating campaign for whatever reason. I could only speculate that reason. A few possibilities are:-

1) He has been misinformed by a source he trusts with a religious fervor.
2) He is a troll.
3) He has some commercial interest in a snake oil device.
4) He has discovered the laws of thermodynamics as accepted now for maybe 100 years are in fact severely flawed (I can't really be bothered looking it up just to help disprove obvious BS).
5) He is from the tin foil hat brigade.

I guess this post might get deleted and I may be reprimanded as I have probably been to honest.

Hopefully we can get back to real science and fact.

As I said earlier I believe that your power increases come from the much more effective charge cooling you get from water over alcohol and that evaporating water, in the manifold only, increases charge density whereas evaporating alcohol in the manifold decreases charge density.

I am pressed for time so I have not read the latest links, but I think the NACA reports will support this.

The NACA was the precursor to NASA and goes back to the Wright Bros and was the research body that lead the way into aircraft performance gains during WW11. In my opinion they are extremely credible. If not, the P51 might have been a dud.

Wikipedia is at times flawed, but it will give a reasonable basis.

http://en.wikipedia.org/wiki/Laws_of_thermodynamic...

This is also flawed. For example they use the term heat where they at times should use the term energy but what the heck. They do a very good job of presenting it in simple laymans terms.

http://www.ridgenet.net/~do_while/sage/v7i1f.htm

Regards
Pat
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hemi (Automotive)
15 Oct 12 21:45
All,
Let me know if the graphics that I inserted in my above 2 posts do not show up. In that case, I will provide direct links to the documents. From there, you will have to load the documents, and navigate to the figures in question.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

Slim3 (Automotive) (OP)
16 Oct 12 2:27
Hemi, The wright engine lost 30 brake horse power power on one cylinder by injection of water/alcohol and that resulted in a loss of 35% of the power that #10 cylinder normally produced? Is that true?

Do you have any info on what the water/alcohol ratio was (proof)? also what volume of alcohol was injected?

I used a 50/50 mix (100 proof ethanol) on the two Dodge engines. I had no method to measure air/fuel ratio. These were both carburetor engines and I fed the Alcohol/water in via a vacuum hose with the throttle at full throttle at a volume that caused the engine to stumble then I leaned out the alcohol with a manual metering valve until the engine cleared up. The system used a sealed glass bottle with the air supply to a tube to the bottom of the bottle so as I adjusted the supply to the engine I could see the volume of air entering the bottle. This didn't give me any figure of how much alcohol was being consumed. I guess I could have done it roughly by measuring how much alcohol was consumed in one 1/4 mile acceleration run and measured how much gasoline was consumed to come to a figure of what the gasoline/alcohol ratio was. At the time I didn't care and was only confirming what the company who gave me several units to test and play with. The only thing at the time that I was trying to confirm or dispute was the Proof of alcohol as they claimed 100 proof worked best. So I tested the one truck on no injection, and almost a dozen different ratio water/alcohol from plain water on up to 200 proof alcohol.
their claim of 100 proof proved to be correct.

The only thing I do know is that the power results were dramatic enough to show on a stop watch. And it did the same on two different trucks.

So I know something was drastically different in the procedure used in that Wright engine tests.

In other tests I ran on another engine I did get about a 35% loss of power in a low compression engine when I switched from gasoline to alcohol and I contributed that to the less BTU value of alcohol verses gasoline. I then raised the compression ratio far past what gasoline can even operate at and gained more power then the engine originally had and could have on gasoline.

Slim3
hemi (Automotive)
16 Oct 12 9:02
Slim3, the point is this. We all know alcohol as a fuel can make more power than normal gasoline, if the engine is setup and calibrated to take advantage of alcohol's combustion properties. However, my post on the R-2800 #10 cylinder investigation was aimed at the question of what is the effect on power adding water or water/alcohol as a supplement (e.g. for internal cooling) to an engine running as intended on gasoline, with no other changes.

In answer to your specific questions about the investigation, your first statement is correct. The ratio of ethanol to water used was 50% by volume. The mass flow of coolant injected is given on the x-axis of the figure I inserted. If you can't see the figure, you can download the complete report here.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

hemi (Automotive)
16 Oct 12 9:50
Slim3, I have to address a statement you made earlier. Please take this in the fully constructive spirit that is intended.

Quote (Slim3)

I noted that in the mid 70's on, when emission control was applied to auto engines, the combustion chamber temperatures climbed higher (thus burning the Nitrogen and producing NOx). However, with the increase in combustion chamber temperature came much lower horse power.

In fact, as soon as NOx became a regulated pollutant, efforts at reducing NOx formation during combustion have focussed strongly on limiting peak temperatures, and did succeed dramatically at both limiting peak temperature and NOx formation rate. This same strategy is at the core of NOx emission control to the present day.
Limiting peak temperature has been done many ways. In the 70s, the tools available were limited and somewhat crude. They were: reduced compression ratio, retarded spark timing, and, at part load, EGR (I believe this was done internally, via valve timing, as well as externally, on various applications). You don't need me to tell you that each of these strategies has the inherent side effect of reducing power.
By the way, a second side effect, that goes hand in hand with reduced power, is increased exhaust temperature. The heat energy that is not converted to pressure pushing down the piston, goes out with the spent charge. From the perspective of emission reduction, this is seen as a good thing, as the increase in exhaust temperature provides an environment in which unburned hydrocarbons can continue to react with available oxygen, resulting in less engine-out HC. Of course higher engine-out exhaust temperatures are typically beneficial to exhaust catalyst operation as well.
A secondary side effect of these peak temperature reduction strategies can be increased heat rejection to the coolant. Some of this increased heat may come from heat transfer from the exhaust ports to the coolant. And some comes from the fact that, for the same vehicle mission, more fuel has be be burned, so the heat rejection to the coolant is increased in proportion to the reduction in thermal efficiency.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

Slim3 (Automotive) (OP)
16 Oct 12 10:44
Hemi, My tests of the two Dodge 318 trucks was done with the engines on gasoline and no alterations at all were made in timing nor fuel mixture. So nothing was changed except the addition of a small volume of 100 proof alcohol to the intake. I first thought it could be the addition of a small amount of fuel as I knew you can gain hp by a richer mixture, but I felt that the small volume of alcohol that was used didn't account for the power received. So trying to think further I thought possibly the evaporation of the alcohol in the intake caused a more dense air charge thus more of everything in. All of this was in the early 8's.

In the late 60's I was an MG, Triumph, Jaguar, Lotus mechanic and we did see lower compression, EGR and leaner mixtures as the main cause of the loss of power. Most of our customers were young and didn't like getting out run from a light by a 53 Buick with an automatic transmission so they came in with tears in their eyes but we being a dealership, could not alter the cars in any way. In 1968 I out ran a mechanic in a new 1968 Jaguar "E"type 4.2 (which in 67 was a 150 MPH car) and I did it with a 66 MGB (1800cc push rod Austin tractor engine) and I did it in every way he want to run, acceleration or top end.
Slim3
140Airpower (Automotive)
16 Oct 12 10:54
Hemi, that is a good an accounting as I've heard of the miseries of the '70s. The industry did a lot of work to get us from there to here. The remarkable advance is all the more impressive when you consider that the auto engine was not a new, undeveloped technology. What was new, however, was the application of computers to every phase of development, design and production and operation and the innovation of computer controllable engine parameters.
patprimmer (Publican)
16 Oct 12 11:26
slim

While alcohol, or at least Methanol and to a lesser extent Ethanol have less energy per unit mass, they also require more fuel for stoichiometric reaction so that in theory all the fuel and oxygen are fully consumed.

The extra fuel required is more than the decrease in energy, so the net energy that can be released per unit of oxygen is about 10 to 15% greater or at least in that ballpark.

If you got a decrease in power from using alcohol, there was an increase in energy waste somewhere, from anything as simple as the mixture was to cold to light off properly at the lower compression. Methanol seems to keep improving at up to about 16:1 CR. With a bad designed chamber/piston dome it can require up to 60 deg ignition advance in an engine that might normally require 35 Deg for optimum.

Although you claim nothing else changed with your tests, you in fact went richer via the alcohol added to the intake manifold. The weaker alcohol made you less rich.

Regards
Pat
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140Airpower (Automotive)
16 Oct 12 11:55
Pat, Good Point, "Although you claim nothing else changed with your tests, you in fact went richer via the alcohol added to the intake manifold. The weaker alcohol made you less rich".
Anectdote: When Pratt and Whitney first deployed water injection for the R-2800 they instructed crews in the field to add alcohol as an anti-freeze. Using Methanol was fine, Ethanol was ok, but when Isopropanol was used, there was a loss of power.
hemi (Automotive)
16 Oct 12 13:25
Slim3, I agree with Pat and 140Air, the power increase you noted when you injected water/methanol in those 318 engines was probably due partly to a slight and beneficial enrichment due to the methanol, considering that the starting point for engines of that vintage was probably lean of optimal for power. And partly due to the evaporative cooling effect on charge density (as shown in NACA Report 756 Figure 6 above).
My remarks in this thread about the effects of internal cooling on power should be taken in a context that assumes that the engine is already running at an optimized fuel/air ratio for power, and the internal coolant is intended for cooling via heat of evaporation and charge dilution, not enrichment of the fuel/air mixture.

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

maxc (Automotive)
16 Oct 12 14:39
Slim3 What was the flow rate of the methanol/water injected in the 318? Did I miss that?
Slim3 (Automotive) (OP)
17 Oct 12 2:20
Sorry maxc, I had no equipment to monitor flow rate and it was always ethanol that I had made with my still. All I did was done with standard mechanics tools. The flow rate was adjusted to a high rate while at a high throttle opening until the engine stumbled and then leaned out just enough to make the engine run cleanly (no stumble or misfire) and that was the method use on each proof of ethanol/water tested, all the way down to plain water. 100 proof did perform best as the company that gave me several injection systems claimed.

Thanks hemi, pat and airpower for all the info as it seems that what you say is that my increase in power on the 318's was the result a richer mixture with the additional fuel (alcohol) and a cooling of the air charge in the intake due to the evaporation of the alcohol and water. Did I correctly understand what you all said?

Slim3
"I'll be back" I am now playing with compressed air as a power source for an engine. Don't dispute that just yet as I already know that the Otto engine is not efficient enough to get any range with what compressed air can be carried on a vehicle.
patprimmer (Publican)
17 Oct 12 2:47
Yep pretty much.

Regards
Pat
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btrueblood (Mechanical)
17 Oct 12 10:40
"I am now playing with compressed air as a power source for an engine. "

Think about liquid nitrogen instead. U of Washington did this awhile back on a little Grumman mail jeep, and wrote a white paper that showed why/how it could be economically feasible.
Slim3 (Automotive) (OP)
17 Oct 12 11:58
btrueblood, I ruled out "fuels" like that due to cost. Can you picture gas stations/markets with liquid Nitrogen in stock for customers and how much would that cost for a fill up? That would get a better range then just a compressed air tank but there is no system set up to refill. I went at it from a different direction and worked on the poor geometry of the Otto engine design in an attempt to make better use of the power applied to a crankshaft. What I came up with was the result of my studies while building a Olds 215 V-8 that starts on direct injected compressed air. Just entered the car in a local car show this last Saturday and won 3rd place in a class with finely detailed cars and mine was very poorly detailed but the uniqueness of the direct injected air start system drew a lot of interest in judges and spectators.

The car manufactures in my eyes are not serious about decreasing the value of oil stock with their electric cars. I can buy a used Hummer and tow a trailer for ten years and be ahead in dollars of someone who bought a new electric car today. The only compressed air cars I can find are for inside a warehouse use or the one TaTa is coming out with.

This subject probably needs a new thread started.
Slim3
140Airpower (Automotive)
17 Oct 12 13:29
slim3, The compressed air engine starter is something unique. Have you calculated the energy capacity of your compressed air tank and figured the cost per BTU?
thruthefence (Aerospace)
17 Oct 12 14:20
The Soviet Bloc M14P radial aircraft engine uses a Compressed air starter. The reservoir tank charges up in flight after engine start, but if for some reason it fails to start, you can pump it back up by hand. Used to be a guy at the airport that has a Sukhoi with one of these things in it.
140Airpower (Automotive)
17 Oct 12 14:33
I've heard of compressed air starting, but never knew if it involved a compressed air motor or directly applying air pressure to the pistons.
Slim3 (Automotive) (OP)
17 Oct 12 16:59
Many diesel truck engines on the over the road trucks use a compressed air powered starter motors but I directly inject compressed air into the combustion chamber to spin the engine over to start this engine.
I designed and built a air distributor keyed to the camshaft and an engage and disengage system so the distributor is not running all the time that the engine is running. The engine runs on gasoline.

I have an on-board air tank to supply air to start the engine. The tank is a 35lb freeon bottle and using 185 PSI, I get only about two tries to start the engine. Right now I just refill the tank from a shop compressor but have designed a two stage 12v compressor to build and put on-board. Barely got the car ready for the car show and no time to build my compressor so I just carried an old Oxy bottle to the show to demonstrate the start system. I have documented all this on my web site just as a hobby.

I heard there was a Russian plane that used an air start system but didn't know if it was a air starter or direct injected air.

I know some WWII bombers used a type of shot gun shell to blow into one cylinder of an 18 cylinder radial engine to start it.

Slim3
Helpful Member!  140Airpower (Automotive)
17 Oct 12 17:21
slim3, I congratulate you on your cleverness. Neat.
hemi (Automotive)
17 Oct 12 19:09
Coffman starter

"Schiefgehen will, was schiefgehen kann" - das Murphygesetz

msquared48 (Structural)
20 Oct 12 20:06
This is a very interesting string, but you guys have really lost me here.

I have been thinking about adding additional alcohol.water injection to my 3/4 ton 1993 Suburban with a gas guzzling 454 to get better mileage for years. If I choose to do this, the test for me will be:

1. Documentable better mileage results in the field beyond the current 12 mpg I am getting.

2. The combination of fuels used to be cheaper than the straight gasoline price - I use 92 Octane.

2. No decrease in power delivered to the tranny and transfer case.

3. No damage to the engine or transmission while doing this.

Idealistic? Perhaps, but the intent is to save a little money and extend the life of the engine is possible. I am still thinking this one through. Thanks for the enlightening discussions here. Keep it up!

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

Helpful Member!  patprimmer (Publican)
21 Oct 12 4:46
Mike.

In my often not humble enough opinion, the only way to get better real mileage is to:-

1) Increase the compression ratio and use water injection to suppress detonation and use the extra compression to gain fuel economy. It might take some time to repay the investment in water injection equipment and a LOT longer to pay for new high compression pistons and their installation.

2) Use water/alcohol injection and cut fuel to correct mixture to previous levels, then forget to count the alcohol as fuel.

3) If you are building the engine anyway, the extra cost then, may not be all that great.

Water is by far the cheapest knock suppressant you can get.

I doubt the alcohol added to the water will be a cheap fuel.

I see the main advantage for water injection being in supercharged engines for knock suppression and therefore allowing more boost to get considerable power rather than economy gains.

Regards
Pat
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Helpful Member!  Slim3 (Automotive) (OP)
21 Oct 12 12:27
Thanks Pat, that pretty much sums up my construction, operation of a still, building of an alcohol engine and the experiments afterwards on my DOE grant. I tried ethanol from wheat and from corn and both worked well in my engine. As for cost in operation of a still to make ethanol, I didn't decrease the cost of the batching process (first part of the operation) but I did lower the cost of the distillation part. (that is what I received the grant for) I found that the cost of the whole process was not as expensive as oil companies were claiming. (up to the 190's proof) They were trying to mislead the public by not mentioning what was expensive. The last process to get from the 190's proof (best a still can do) to 200 proof necessary to mix in gasoline to prevent separation.

While it is true that using corn does raise the value of corn thus a cost increase to the public of a food source. When using corn that is slated for livestock the cost was not raised much, because the nutritional value of the mash after distillation is the same as it was before. Admittedly you need to get all of the alcohol out of the mash before feeding it to livestock as I had some wobble legged chickens wondering around my property after feeding them my mash after distillation.

The use of sugarcane instead of a grain would dramatically lower the cost further as much more ethanol can be had from an acre of cane then from any grain as Brazil knows. Secondly, two expensive procedures during the batching process can be eliminated that turn the starch into sugar that yeast can eat. Plus my tests proved that a very high compression engine runs as well or better on as low as 170 proof over the same engine running on 200 proof.

So I contend that we should burn our alcohol and tell OPEC to drink their oil. Also tell our own government to only trade grain for oil and put some clamps on our own oil companies. Maybe then we would not be financially raped every time we went to fill up our cars. Also send a message to the auto manufactures to get serious about fuel mileage instead of what they are presently doing.

Slim3



msquared48 (Structural)
21 Oct 12 15:12
Slim3:

Thanks Pat. If I have to rebuld the engine at 218,000 miles to get better mileage, it will not be worth it in the long run, hands down. Maybe if it was a new engine and I was 20 years younger... :)

Did you ever investigate using cat-tails instead of corn?

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

patprimmer (Publican)
21 Oct 12 17:16
Mike

I think your post is out of sequence a bit. I am sure the first response was to me and the last comment was for slim.

slim

I agree that using a simple still that still leaves a bit of water in the alcohol is the best method so long as you don't try to mix the alcohol with hydrocarbon fuel in the tank.

To get the best gains, you should correct for total fuel to air by counting only the actual alcohol content of water/alcohol from the injection system. You should reduce the hydrocarbon fuel to compensate for the alcohol. This would be near on impossible with a normal reasonably modern automotive carby. I can't remember ever seeing one with an on the fly lean out or adjustable main jet.

I guess if you blocked the power valve circuit and did not increase the main jet to compensate then injected alcohol via a separate system at the point where the power valve normally opens to give power a:f rather than cruise a:f, however I don't think the change would be enough.

A solar still might change the economics of making your own alcohol, or burning waste vegetable matter from the crop supplying the starch/sugar. I doubt the waste vegetable matter is enough heat to run the still.

There are a lot of variables to study to optimise this due to the higher cooling from the evaporation of the water content of the 170 proof alcohol and the higher displacement of air in the manifold from the alcohol portion as it evaporates and the changes to cooling/displacement of air balance as the alcohol:water ratio changes. Engine speed, manifold runner and plenum and port and valve size, cam timing, compression ratio, quality and timing of spark, load at cruise and power required at WOT are all going to impact on the optimisation.

At low speed high vacuum, a higher portion of the evaporation is going to occur in the manifold, but at lower vacuum and higher speed a higher portion of the evaporation is going to happen during compression and even after ignition.

Regards
Pat
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msquared48 (Structural)
21 Oct 12 17:41
Pat... you're right.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

Tmoose (Mechanical)
21 Oct 12 20:32
http://aly-kotah.com/93suburban.pdf

That says it has 7.8 to 1 Compression ratio. Why are you buying high octane ?

And some form of EFI. And a CD of .457.

What rpm do you turn on the highway at 65 mph?
How much of you driving is highway, and how fast do you go?
Is it 4WD/AWD?
140Airpower (Automotive)
22 Oct 12 0:13
Wow, this is going to be an expensive vehicle to drive no matter what you do. 12 mpg is doing well IMHO. I used to get 13.3 in my '72 Camaro.
Mike, do you get pinging when lugging it? 7.9 CR is that low for reasons of luggability, like rpms in the 1,500 range under load. If you get pinging, a simple, plain-water injection system will stop that. It will also clean the carbon out and that might help your mileage just a tad. But, normally water injection is not known to increase fuel mileage no matter what the claims of people selling systems. Also, substituting alcohol should reduce your mileage. In fact, 92 octane should reduce your mileage just a couple of percent compared to 87. If you are using 92 to avoid pinging on 87 then a little bit of water injection, just enough to stop pinging on 87, would probably be the best bet. Save you some money.
Slim3 (Automotive) (OP)
22 Oct 12 1:59
Pat, At the time of the tests of the injected Ethanol/water in the Dodge 318's, I adjusted the flow into the intake manifold at high RPM and adjusted it rich until it stumbled giving it the max alcohol/water that it could handle in addition to the preset gasoline, then leaned that alcohol/water down until the engine cleared up and then ran a 1/4 mile acceleration run. I was not looking at or for fuel mileage. I only wanted to confirm what the company said and that was that a 50/50 alcohol/water mix gave the best hp. The increase in power was easy to feel and the time in a quarter mile confirmed it.

What you said earlier that the power increase could very well have been due to a lean gasoline setting and the added fuel (alcohol) gave it a richer mixture and more power. However the same tests run with 180, 190 and 200 proof and a 160, 150 and plain water tested the same way showed little to no increase in power over just gasoline. That is what surprised me and I couldn't see why.

The Triumph TR-7 with the compression raised (too high) was run on straight alcohol/water and no gasoline at all and I had jacked the compression up so high I couldn't even start it on gasoline without serious detonation with Turbo Blue with an octane booster in it. So I had to design a pair of intake air stream heaters for both constant velocity carburetors to start it on alcohol.

The acceleration tests were very dramatic but I had to make my own metering needles for the carburetors and I found that ignition timing ended up at about the same as gasoline. I guessed that the slow burn of the alcohol would normally require a more advanced timing but the high compression sped up the flame to bring it back to what gasoline required.

Slim3
msquared48 (Structural)
22 Oct 12 2:31
140airpower:

I get no pinging whatsoever with the 92 octane, even under high load as in towing a 30 foot trailer over the summit climb over Stevens Pass at 50 mph. - keeps the plugs clean as they foul at lower octanes.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

hydroman247 (Mechanical)
22 Oct 12 3:12
12mpg from a road vehicle :O

I think you can be shot in the UK for that. :P
140Airpower (Automotive)
22 Oct 12 8:39
Mike, I'm surprised you get fouling with 87. Does anyone have an insight into that?
patprimmer (Publican)
22 Oct 12 9:20
It's got me completely beat.

Regards
Pat
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140Airpower (Automotive)
22 Oct 12 10:12
The only thing that comes to mind is oil consumption vs detergent in the gas. 92 is apt to have more detergent. The work-around that comes to mind is the next hotter range of plug for 87. But then you are more likely to get pinging. Also, water injection in an oil consuming engine is less appealing due to cooler running and plug fouling.
Mike, how much oil do you burn?
Tmoose (Mechanical)
22 Oct 12 12:25
93 is pre OBD2.
I wonder what diagnostics that old system supports, and if the Check Engine Light is even still functional, to tip you off about system problems.
msquared48 (Structural)
22 Oct 12 13:13
This engine is tight - no oil burning, just leaks a little at the crankcase - need to replace the seals when it gets a lot worse, but OK for now.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

msquared48 (Structural)
22 Oct 12 13:30
For the record, this is not our primary vehicle, but our work, hauling, and recreational vehicle. It is not used for day to day excursions. At that mileage rate, I could never afford it. We have a 2007 Prius for that. It has over 10,0000 miles on it now.

Interesting thing for this vehicle is that it has never even come close to failing emissions. Always less than 10% of allowables.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

140Airpower (Automotive)
22 Oct 12 14:29
Mike, it's hard to understand plug fouling. I haven't encountered that since they got rid of lead, but I know that oil fouls plugs, also an ultra-rich mixture might do it. Don't know of anything else. Passing smog is a sure sign of an engine that's running right.
msquared48 (Structural)
25 Oct 12 2:21
I just put 39.1 gallons of 89 octane in the tank. We'll see how it runs... $160.00!

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

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