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The future of the engine as we know it

The future of the engine as we know it

The future of the engine as we know it

(OP)
I normally run like crazy when someone asks me questions about a "new" engine, but when one of my directors asks me to evaluate a "new design" design, my knees shake.  That happened this morning.

We have seen free pistons, opposed oscillating pistons, scotch yoke pistons, toroidal blocks, ball valves, sliding sleeves, and tons of other combinations.  Strangely, or not so strangely, none of these has ever reached any significant success.  The old, inefficient Otto cycle engine still hangs around.  With the exception of sealing refinements and air-fuel metering, almost nothing has changed in 100+ years, not including OHC engines which is a refinement, or phased cams, also a refinement, or exhaust aftertreatments, which is not a refinement, but an attempt at fixing an engine inefficiency.

I wonder how long it will take before something else pops up and takes a reasonably strong stand against the tried and true engine design?

Lets look at the true IC engine replacement, not hybrids (although I feel that is where we are heading for the next 25 years).  Turbines are nice but not practical for a number of reasons.  

When we look at H2 as a potential fuel, it still uses the Otto cycle engine as a base, only the fuel has changed.  Are we really gaining anything on the engineering side?  I recognize the significant advantage on emissions, but fuel transport, storage, and infrastructure have still to be perfected.

Any ideas, fellow engineers?
Franz

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RE: The future of the engine as we know it

Would you classify the Wankel rotary as a variant Otto cycle?

RE: The future of the engine as we know it

(OP)
Since it operates on 4 cycles albiet in a different format, wouldnt it be considered an Otto cycle?
Suck, squeeze, bang, blow, along with a throttle, ignition, etc.
Works for me.
Franz

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RE: The future of the engine as we know it

Suck, squeeze, bang, blow also describes a jet turbine.

RE: The future of the engine as we know it

(OP)
Thats a stretch, but I agree with your comment, but to classify the turbine as an Otto cycle?  At least, that process is continual and not in significant sequences as the IC engine.
Franz

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RE: The future of the engine as we know it

Gas turbine engines are still internal combustion (IC), right?
  

RE: The future of the engine as we know it

franzh,

The recip piston, Otto cycle, internal combustion engine is improving at a rate much faster than its proposed rival, the fuel cell. And there are still many significant improvements coming.

The main areas I see for future improvements in the Otto cycle piston engine are variable compression, variable displacement, various schemes for optimizing piston motion, and waste heat recovery through turbo-compounding (electric assist) or other techniques.  There are also some improvements that can be had with real-time feedback provided by in-cylinder combustion sensors.

I used to work with this old German engineer, who would respond to predictions of the demise of the internal combustion engine with the following:

"The hearse that drives you to the graveyard will have an internal combustion engine".

RE: The future of the engine as we know it

(OP)
We are pulling at semantics classifying a turbine engine in the same category as the Otto cycle piston and valve engine.  As good as the turbine engine is, it really shines in constant load applications, far superior to the piston engine, but it cannot compare to the piston engine for throttle response and manufacturing costs, necessary for daily driving and private operation.  Toss in the efficiency of the turbine compared to the versatility of the piston engine and we have a real discussion.

The conventional piston and valve engine has made significant advancements over its century plus life, certainly nothing to sneeze at, but most of the major advancements have been made in the last 20 years when electronics took a major role in design and controls.  Recognizing the items "tbuelna" lists, these are still refinements of the original design, basically correcting and improving on a design that originates almost 150 years ago.

Where do we go from here?  In my lifetime, or at the end of it, I too will be taken to my grave in a hearse powered by an Otto cycle engine, most likely.

The fuel cell will increase in popularity, but there is going to be a point where increased production will not significantly lower the cost per kilowatt, and we will need more power to make a transference of dominance between the piston and fuel cell powerplant.

Surely there must be something in the interim.

Franz

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RE: The future of the engine as we know it

Diesel Cycle engines are becoming increasingly popular in personal transportation due to the increased efficiency compared with Spark Ignited (~Otto Cycle) engines.
Gas turbines approximate the Rankine cycle, I believe.
All have there advantages and disadvantages.
The basic mechanical engineering was fairly well thought out 100 years ago.  The big advances have been materials and electronics (thank you DOD and NASA).  The advances are helping the engine types compete where they traditionaly did not have an application.

RE: The future of the engine as we know it

Fascinating stuff.

A hundred years ago we had DOHC four valve per cylinder engines, and even turbocharging. In some ways not much has changed, but in other ways the perfection and understanding of the basic process has evolved vastly.

I see future improvement in fuels and lubricants, engine management, materials technology, computer simulation, and a whole host of other things.

Evolution not revolution.

 

RE: The future of the engine as we know it

(OP)
Warpspeed:  Evolution is correct, as everything has up to date, but at some point, we have created what may be the most efficient piston and valve IC engine, where even better development is far more difficult and expensive than the gains.  We have seen the gamut in technology with the resurfacing of turbocharging and supercharging, variable cam timing, SAAB's variable compression engine, and so on.  What we are doing is evolving the engine.  True, we had DOHC 4 valve engines a century ago, but were they 2 litre 8000 rpm 600 bhp?  That is the true note of evolution, thanks to electronics, lubrication, material selections.

With computers, we have the theory that the speed of the processor shall double every 18 months, and it has done so, but they have hit a stumbling block with the capacity of the pathways hitting the width of the laser in NM.  

Wonder when we will hit that same point with the IC engine, where there just may be no further development possible?  I consider the newest generation of engines the epitomy of engine technology, truly the best of the best, but then someone squeezes a little more, makes one a little cleaner.
Franz

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RE: The future of the engine as we know it

I'll just jump on my usual bandwagon and say that the Prius, in particular, has the potential to remove most of the problems associated with running less flexible, but more efficient, engines as the primary energy source. Admittedly, this comes at a huge weight penalty.

I'll jump back off the bandwagon, and ask, is the current choice of materials the limit on SI engine efficiency? How about CI?

Certainly for production SI engines we do some very stupid things, efficiency wise, to keep the exhaust valve and cat cool.

Oh, and perhaps I am still focussing too much on thermodynamic efficiency. I see no real sign that the consumer marketplace is much concerned with efficiency in any real sense.

Cheers

Greg Locock

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RE: The future of the engine as we know it

(OP)
This group has had this discussion before.  Are the Prius and other new generation hybrid vehicles engines actually the source of efficiency, or is it the total package?  The cost of fuel going in, versus the energy derived and applied to the ground.  I like the hybrids for the gee-whiz factor, but for pure engine efficiency, are these engines that efficient?

The Prius, Honda Civic, and other semi-related hybrid projects are currently cutting edge, but the Honda Civic has their high fuel efficiency engine that approaches the economy of the Hybrid, as does Toyota (American market) and others.  Not having access to the much of the worlds offerings limits my exposure, but I am certain that there are other options.

Down to basics:
With the exception of some materials selections and minor engine developments, the engine has remained unchanged from the turn of the century (the last one) up until post war, around 1950.  Lets see if this is an accurate recollection:

Overhead valve engines were common place, improving air and fuel management, late 1940’s, and I know there were some pre-WWII, but widely accepted OHV engines were not generally available until after the war.
European manufacturers used the OHC engine, leaping over the US manufacturers.
Thin wall castings reduced engine weight;
Staged venturi carburetors improved on air and fuel mixing, improved power at low speeds and helped with emissions, something of little concern in the 50’s and early 60’s.
Early emission controls like the EGR valve and Air injection system.  Are these developments or patches to cover up an engine design deficiency?
Electronic ignition;
Early electronic fuel injection;
Electronically controlled carburetion disasters of the US 80’s.
Central single point fuel injection;
Bank fire fuel injection;
Sequential fuel injection;
Tuned intake manifolds help with power;

But, almost all of these systems use engines designed in the 1950’s and 60’s.  The 1990’s introduced the computer designed clean sheet engines which are further refinements of the earlier designs.  In the US, the Chevrolet small block was the engine used from 1955 until 2002 with almost no significant design changes, Ford used the small block from 1962 until 1998, and Chrysler is still using their small block, first introduced in 1965, still in production.  Air management and electronics are major developments, but the basic engine is unchanged.  Was that because the engine was that good, or “why reinvent the wheel”?  Ford now uses the modular engine, which is quite good, and GM is using the LS engine, which is quite good too, and they are clean sheet engines, designed for emissions but serve double duty as good powerplants.

The consumer has no real care about thermodynamics, only that the automobile starts with the first twist of the key, has reasonable performance, costs as little as possible to operate, has no unexpected breakdowns, and frankly, emissions are far down the list.  US manufacturers have found that advertising a car has having low emissions has little or no impact on sales, but change the interior color or add a nice sound system, and now we increase sales.  See the phenomenal sales of the grossly overweight SUV market proves that the consumer has little concern for emissions or economy, only status and usability.  Also, I own one too, but was lucky in my selection as it performs well with economy and emissions.

Early in my career, I read that we will see ceramic engines and engine components that will last forever, ultrasonic fuel atomizers to insure proper fuel distribution, plasma ignition for total combustion, cylinder head inserts for heat reflection, and so on.  Ultra capacitors will be used for starting and electrical load, no starters and no alternators.

What next?
Franz

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RE: The future of the engine as we know it

I am on record in this forum as having predicted the advent of diesel as the worlds primary automotive fuel.  I base this on recent activity in the arena of the Fisher Tropsch process of converting (stranded) Natural Gas (and/or coal or other suitable hydro-carbon) to light distillate.

The fuel that this process produces has already found favor in some USA markets like California because of it's ability to A) blend with petroleum diesel to reduce sulfur emissions, and B) eventually replace sulfur bearing petroleum diesel as an "acceptable" fuel.

Europeans, whose governments tax the fuel quite heavily already care about the Otto cycle efficiencly of the diesel engine over gasoline, and seem to be leading the charge.

There is a lot of NG around the world that not much else can be done with it other than convert it to a marketable product (ammonia, chemicals, F-T diesel, etc.)  Some of the owners of this gas seem quite serious about going down this path.

Just my $0.02.

rmw

RE: The future of the engine as we know it

(OP)
The diesel cycle circumvents many inherent deficiencies present in the Otto cycle/4 cycle throttled engine.  There is a lot to say for the diesel engine efficiency, those that I praise.  The FT process, and other related GTL projects are gaining in popularity, and when enough of the product becomes in demand to drive the prices down where they are directly competitive, we will see more of a concerted effort towards CI engines.
Also, look for more Ethanol-Diesel blends, just 10% Ethanol has shown positive benefits over standard #2 diesel.
If I had my choice?  I would buy a diesel, but my missus would refuse to fill it when she drives, says its “stinky”.
Franz

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RE: The future of the engine as we know it

Sorry Franz, I wasn't clear. The Prius transmission is effectively a full authority CVT, AND has energy storage. Therefore you can afford to run an inflexible engine, at its optimum operating point for the required power demand, and rely on stored energy the rest of the time. In my opinion none of the other hybrids come close. A Prius transmission with an efficient diesel/turbine cogenerator setup would be my choice for a near term solution if the current fuel economy fad persists.

Incidentally, the total energy stored in the battery is about the same as a pint of fuel!

Cheers

Greg Locock

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RE: The future of the engine as we know it

Here's my take on this thought provoking question. Unless battery technology makes a major break through in the next 10 yrs. I'm going to my grave in an IC powered hearse. Given the average life expectancy and the lord willing I've got about 20 yrs to go. I think further improvements in the IC engine that will occur in that time will come from efforts to cut down thermodynamic losses on the exhaust and cooling system. I think a homogenous charge 2 stroke turbo-compounded diesel with ceramic coated piston head and combustion chamber, seems like the next logical progression in IC engine development. Given current technology in materials and manufacturing this should address fuel ecomomy and emission issues. Politics and economics will be the determining factor as to how quickly this will occur.----------Phil

RE: The future of the engine as we know it

I guess it's time for me to add my two cents...

I have stated before that H2 will never be widely used as a motor fuel, period.

I drive a diesel truck but I see no future in diesel power in general transportation unless the automakers undertake a massive advertising blitz to convince the average driver that diesel is not, as Franz put it, "stinky".

The current fad/trend in SoCal is the "hybrid". Anecdote: My tax accountant has two Prius approaching five years old...so far, so good---one approaching 150,000 miles with no maintenance.  My question is...What happens when all these batteries must be replaced after the warranty period?
At this time you cannot find a Prius in my area to buy unless it's used and only then at a price that generally exceeds the MSRP of a NEW car!

Franz, I agree with most of what you post. However, Buick never produced anything but OHV engines (The Marquet used a side valve Olds engine).  Chevy used OHV fours and sixes (Chevy had an OHV V8 pre 1920 but did not procuce it).  The "flathead" was popularized by Ford, of course, but in the pre WW II era, flathead and OHV engines were of similar HP output and reliability...cost being a big factor for continuing the flathead into the 1950's (along with Henry Ford's single minded approach to auto production). Cost of production change was most likely a factor with Chrysler and others (even Packard had  pre war OHV engines).
Of course...the exotics...DOHC, SOHC,etc. widely available at premium prices. Early aircraft engines (WW I) were OHV, e.g., Liberty, Hispano-Suiza, etc.
My point with all this is to point our that, IMO, 1950 was NOT the departure line from 'old tech' to 'new tech'.
If I were forced to pick ONE day where the transition began...December 7, 1941.

Rod


RE: The future of the engine as we know it

Rod, one thing you may be overlooking in regards to diesels would be the biodiesel revolution. For the diesel to take over in the US, the majority of fuel sold would be required to be something other than petroleum based, and by all accounts I have read, even Bio. produced from Algae has none of the stink associated with dino. diesel.

When I finally do get to converting the wifes car to diesel, she will have exactly 2 choices, fill it or.............

RE: The future of the engine as we know it

... ceramic engines and engine components that will last forever

It's "cost of ownership".
Most cars start to look pretty beat up with 200,000+ miles on them... How much value do you add to make the engine run 300k? 400k?

" ultrasonic fuel atomizers to insure proper fuel distribution"
why would you bother when the efi multipoint handles that very well?

"plasma ignition for total combustion"
huh? who cares? 100k miles on a set of plugs, they run plenty clean enough for the cat to clean up (think you can make the plasma ignition good enough to eliminate the cat converter?)
"cylinder head inserts for heat reflection"
? the name's Rogers... Buck Rogers.
(or is it Tom Swift?)
Yes, definately if you could reflect/stop heat transfer into the head & valves you could improve efficiency and reduce heat load on the cooling system.
(what was that about cost of ownership?)

" Ultra capacitors will be used for starting and electrical load, no starters and no alternators."

huh? An Ultra Cap is just a means of storage. How ya gonna make those electrons spin the crankshaft?
How ya gonna recharge the Ultra Cap after using it to start the motor and run the lights and accessories?
  
Jay



Jay Maechtlen
http://home.covad.net/~jmaechtlen/

RE: The future of the engine as we know it

(OP)
Jay;
All good points.  In 1980 I attended an advanced automotive SAE Toptec workshop where technology was discussed, presumably for the next 20 years.
One presenter was there who was trying to market a ceramic engine, or an engine with a significant amount of ceramic and/or composite components.  He discussed using ceramic cylinder head inserts to retain the heat in the combustion chamber (Detroit Diesel and Cat both experimented with them I'm told), cylinders made of a ceramic that would not wear that were honed with a diamond dust tool.
Plasma ignition was not especially targeted at longevity, but at an extremely hot discharge, igniting all of the fuel mixture.
One presenter demonstrated an ultrasonic grid that was installed below a conventional carburetor body that vaporized the gasoline so fine as to turn into a cloud.  Not those hyped mini-superchargers that install in 30 minutes and cost $38.95, in the back of hobby magazines.
The ultra capacitors are practical, and there are cars today that are starterless and alternator free, (at least as we know them) with the components mounted in the flywheel.
Now, as we have seen, Buck Rogers flying suit never materialized, but we have automobiles that are levels of magnitude cleaner and more efficient today than 30 years ago, and the cars of 200,000+ miles are normal, not the rare exception.  I firmly believe we can thank the emission requirement warranties for that push.  We have succeeded there, but what's next?
Franz

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RE: The future of the engine as we know it

Pat, your a brave man.  Let us know how THAT idea turns out.

The "stinky" reference was a euphemism. The fuel in California is so sulpher free as to be nearly "non stinky" anyway.  I simply ment that it's going to take more than technology to convert the American driving public to diesel power.  It can be done, certainly, but not without a massive publicity campaign.  American drivers have no idea of what they want unless they "see it on the telly"!

Rod

RE: The future of the engine as we know it

if the starter/alternator are integrated into the flywheel area, (now becomes a motor/generator) it is still there...
Maybe you get rid of the serp belt, maybe you still drive the p/s pump, water pump, and a/c with it.
I know, there are electric p/s systems, etc...
Just need an efficient, high power charging and storage system.
As I understand it, there was an adiabatic diesel engine project some years ago- ceramic everything, and no cooling system. Wast heat was rejected through the exhaust and by convection/radiation.
I wonder what the results were?
cheers
JAy

Jay Maechtlen
http://home.covad.net/~jmaechtlen/

RE: The future of the engine as we know it

(OP)
Ah, you remember it too!  Rumor had it that it was a Caterpillar prototype, a 4 cylinder engine, rated around 90 bhp.  I heard that the radiator was the size of a cigar box, or close to a conventional heater core.  Sometime in the early 80's.  Never saw it, but heard stories by several independent sources.
If a flywheel mounted starter-alternator were used, then all accessories could be remotely mounted, then driven only as much as needed, ie: water pump, air conditioning compressor, power steering, etc.  I can see power advantages there.
I had heard that Chrysler was looking into it with their Dakota Hybrid that was supposed to be out last year.  A V-6 with hybrid assist on the front wheels, conventional drive to the rears.  Wonder what happened to it?
Franz

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RE: The future of the engine as we know it

I thought it noteworthy to the topic of this thread to note that while watching a show on Fox News this AM called Forbes on Fox, one of the participants recommended the stock of Sasol (SSL) of South Africa, a company that developed a lot of the GTL technology when SA was isolated during apartheid.  The stock analyst actually spoke quite intellegently about the GTL concept and Sasol's involvement in some of the current plants being built around the world in his recommendation of the stock.

So, it is not just engineers watching this technology.

rmw

RE: The future of the engine as we know it

Thanks, Tbuelna

I have been following that situation with interest for some time now, as well as the recent news that Qatar just put the slow down on a similar deal with Conoco/Phillips, I think it was.  If there wasn't something to this concept, those big boys wouldn't be playing in this ball park, so to speak, hence my original post in this thread earlier.

Even this is an automotive forum, and thread, I think it also has ramifications in any industry that currently uses Natural Gas as a power generation fuel and can easily convert to diesel, and is located where infrastructure exists (ship and barge unloading capabilities, or near products pipelines) for diesel delivery.

For my part, in my younger days, I started up plenty of Gas turbines dual fuel, Nat. Gas and #2 oil fired.

Automotive is, in my way of thinking, ripe to make the initial rapid advances for the first fuel produced by this process.

rmw

RE: The future of the engine as we know it

Franz,

Until recently, most advances I have seen in the industry have revolved about extracting energy from a liquid fuel, petroleum based for the most part.  The quality of the distillates have improved from years prior but I do not see any great breakthroughs occuring in petroleum distillate technology.  So engineering efforts will be guided at more effectively squeezing every ounce of energy from the petrol with as little heat wasted and as few emissions as possible.  With the Otto cycle at approximately 28% efficient, there is alot of room for improvement, but new materials or not, we are in the exponential portion of the curve where many R&D dollars spent here will not add a representative gain in efficiency.

So where next?  Why make it better at all?  The main push seems to be the fact that the petroleum resource if finite and/or the environment is affected by the byproducts of the human transportation process (heat, emmisions).  So we need to make a device that transports humans using an infinite, cheap fuel source with no measurable impact to the environment while allowing high speeds and quick acceleration.  Oh utopia!

As mentioned earlier, batteries are just not there yet.  Lead acid, the bulk of the automotive state to date, is far from cutting edge but reliable and readily available.  We can get lead and sulfuric acid rather easily.  But what to do when the meriad of batteries need refurbishment or replacement.  Petroleum based fuel consumption is down in the hybrid, but the storage of environmentally unfriendly used lead, acid and the plastic battery cases become the problem.  If a completely electrical car is the course, then the non nuclear power plants centralize the polution efforts instead of spreading them to the individual vehicles.  For an environmental system, the pollution is not appreciably less over time.

So that leaves alternatives such as fuel cells and solar power.  Fuel cells presently have more promise near term, but I predict that eventually solar cell technology will be the winner combined with fuel cells.  Solar during daylight hours and fuel cell at night.  Recycling will come into play with hybrids to slow the battery issue as better batteries are produced, but with all of these, the consumer will not be happy with a mode of transportation that achieves 0-60 in 25+ seconds or a system with a maximum speed of 40 MPH.  Thus the main reasons the Otto cycle is still around .... vehicle provides the individual the ability to go where they want, when they want, quickly at a relatively low cost.  

I ask what are the alternatives if petrol were to disappear tomorrow?  That is the longterm (100+ years from now) we should be exploring now.

My .02 cents.

Brian Barnett

RE: The future of the engine as we know it

(OP)
Brian;
I couldn't agree with you more!
I see a renewed push for the diesel engine (here in the US, the diesel engine never really caught on with the general public).  It's efficient, allows for relatively transparent operation to the consumer, powerful, and not "rocket science".  I'm surprised there is not more interest in a diesel hybrid for the consumer market.  Ford was looking at a hybrid Taurus around 1998-2000, but it never materialized.
My thoughts on the disappearance of petroleum products?  Probably within our lifetime, exponentially more acute after 2025.
What do I see as an alternative?  OUCH!  Try to retrain the American public in living and working communities, mass transit, rely less on travel, and so on.  The list appears endless.  I really do not see a drop in replacement for fossil fuel, it all comes from the same place.
Franz

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RE: The future of the engine as we know it

In my comments earlier in this thread, I limited my remarks to GTL progress and possibilities.

Regarding running out of fuel for autos in our lifetimes, as long as we have the proven coal reserves we have in this country and other parts of the world, that is probably not a worry.

Check the following link.

http://www.rentechinc.com/pdfs/WBC-Presentation-4-14-05.pdf

rmw

RE: The future of the engine as we know it

In the long term we will need to look for energy from where it all came from on the first place: nuclear fusion. Shame cold fusion didn't work out...

RE: The future of the engine as we know it

franzh/Terry:

It is coming. I should get my compressor/combustor by next week, and send it off for starting and ignition work thereafter. Variable nozzles, etc., reserved for phase 2 testing. The free power turbine and turbocharger are purchased and waiting.

The answers are, in order, HCCI, greatly reduced time for heat to transfer to the cylinder walls; followed by: free piston, gas turbine, true constant volume combustion, lean running, variable stroke, 50:1 compression ratio, Miller cycle, Pescara cycle, very low engine friction, aggressive turbocharging, double-acting 2-cycle combustion, direct in-cylinder fuel injection, zero NOx, tripled torque vs. hp at zero rpm, tripled power/weight, halved manufacturing costs, essentialy maintenance free, runs forever.

No hybrid drivetrain. Runs on unleaded gasoline, around 70 octane or lower. Or kerosene.

Something like that.

Schwee

RE: The future of the engine as we know it

schwee,

Sounds expensive.  Did you win the lottery?

RE: The future of the engine as we know it

Nope -- I've been working with a partner for the last two and a half years, who knows more about adapting APU-type gas turbines to novel purposes than about anyone I've found. He owns about ten of them, and has donated one to the project. He'll also handle all integration of the free-piston gasifier with the turbine (Allied Signal JFS-100). And provide testing facliities and expertise (yes, he does have some fairly serious resources).

All I have had to do is get the gasifier built, and that's in its final stages. Really quite a small inivestment. Money-wise, anyway. Nothing to it. ;o).

How is your project coming?

RE: The future of the engine as we know it

I don't see how hydrogen (fuel cells or not) could ever play a major role in powering vehicles either. Even if they solve all the distribution, storage and safety issues, diesel will always have 15.6 times the power density per volume of compressed hydrogen.  
http://www.osti.gov/fcvt/deer2002/eberhardt.pdf
Why all that brouhaha about hydrogen?

I wonder though whether methanol fuel cells (DMFC) might be able to substitute the IC engine at some point?
http://www.fctec.com/fctec_types_dmfc.asp
http://www.dpreview.com/news/0406/04062401toshibafuel.asp
Currently DMFCs don't reach the power density required to propel a vehicle, but maybe they could in combination with high power capacitors like these:
http://ecl.web.psi.ch/Publications/cap_pub/AABC_2002.pdf

Also, I don't think the gasoline engine is dead yet. Wenko built a gasoline engine with an extremely high power to displacment ratio at relatively low rpms using a pressure wave supercharger. (Less weight and higher efficiency at partial throttle settings.)
http://www.swissauto.com/e/projekte.e/technischedaten.e.jsp?ID_Display=200004
http://www.swissauto.com/uploadfiles/EN_200056.pdf
Besides ethanol can also be used in a gasoline engine. It has a higher knock resistance than gasoline and would therefore allow a higher compression ratio or boost pressure. (Of course, Americans could then say: We grow oil on our own soil. And we fund American farmers instead of some corrupt Kings in the middle east.)

RE: The future of the engine as we know it

My project has been moving along slow and steady.  I have a development (2.1L, 4-stroke, spark-ignited) engine on the dyno and it's working quite well.  

My first patent on the engine was just issued on Sept. 6th. I'm also currently in the process of designing a 350 hp compression-ignited engine.  

I'm working on the project full time now.  But I haven't yet secured enough money to fully pay for the diesel effort. I have submitted proposals to DARPA/DOD for some research funds, but will not hear back from them for a few months.

Glad to hear your project moved from the drawing board to lab.

RE: The future of the engine as we know it

No one has mentioned vapor recovering engines. Did they fall by the wayside?

I worked on a 300HP model for aircraft of all things thought it would make a nice generator

RE: The future of the engine as we know it

(OP)
One thing to remember gents (I assume so) is that no engine is 100% efficient.

In a recent lecture, one audience member challenged me to a series of technical questions.

When he posed that his engine was 80% efficient, I asked if he had ever burned his hand on the exhaust manifold, he replied "yes, several times".  Hmm, exhaust radiant heat.

When asked if he was using a radiator, and at what temperature the coolant was, he replied "Just about what a typical car runs".  Hmm, coolant radiant heat loss.

When asked if he had a transmission, tires, driveline, and engine accessories, he stated that those were necessary, and the same answer when asked if the engine had pistons, rings, camshaft, valves, oil pump, and coolant pump.

We are getting pretty good with the IC engine as we now know it.  Only a very few engines are able to break the 30% range for motor use, and the upper 30% for OTR CI engines.
Turbine applications have more theoritical effeciencies, but as long as there is waste heat, there is energy loss.

Is the answer recovering the waste heat and totally transforming the thermodynamic capabilities of the fuel to usable energy?

Franz

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: The future of the engine as we know it

I'm not an expert but even if you can recover all the waste energy I don't believe that any engine could ever surpass the efficiency of a combined cycle power plant which I think is around 65% max. (The larger the engine the inherently smaller are the frictional and heat losses):
http://www.power-technology.com/projects/san_joaquin/san_joaquin3.html
Diesel engines in passenger vehicles already reach 45%, so there's not much to gain anymore unless we switch to fuel cells (which don't generate a lot of heat in the first place).

I think the answer is (which is partially taking place anyway):
* Making the car (and its engine lighter) and reduce drag. (Why do we need a  3500 lbs. vehicle to transport 250 lbs. on average?)
* Recycling brake energy.
* Make the engine more efficient particularly at partial throttle settings. (I think I drive about 90% at partial throttle).

I just realized that I should have said energy density of diesel vs. hydrogen and not power density in my previous post (but I can't edit the post).

RE: The future of the engine as we know it

Terry -

Congratulations on the patent! That's exciting news. What about just hauling your test engine to their location? No substitute for the real thing to generate interest. Or to a manufacturer?

globi5 -
Very interesting article. I haven't had time to look through it completely, but they clearly grasp the basic challenges facing IC engine efficiency, and they seem to have a realistic plan to address them. Is there more information available?

RE: The future of the engine as we know it

The whole project of the car with the high power density engine was funded by greenpeace (they wanted to show that it is possible to build a relatively inexpensive 80 mpg car without diesel, hybrid, fuel cell or solar technology.)
http://www.autoweek.com/article.cms?articleId=103222 (It's actually not a hybrid as this article falsely claims.)
http://archive.greenpeace.org/climate/smile/faq/faq3.html
Also, the original Smart (www.smart.com) owned by the Swatch-group was supposed to be fitted with a similar engine before it was sold to DaimlerChrysler which decided to provide it with their own 600cc turbocharged 3 cylinder instead.

Here's more info about the pressure wave supercharger (it was originally invented by BBC (now ABB) about 50 years ago):
http://www.swissauto.com/uploadfiles/EN_200012.pdf
http://www.autoreview.ru/new_site/year2002/n07/mazda_old/800/tehnik3.jpg
As with the Miller cycle engine Mazda was the only company that actually lead it into production (well as far as I know). I don't know why Mazda stopped producing them? Maybe because turbochargers were massproduced and readily available and it was therefore not cost effective?

RE: The future of the engine as we know it

globi5 --

I'm with you on the idea of making the engine efficient at low throttle settings. That is the crux of the issue, because you are right, 90% of most driving cycles is done at partial throttle.

In automobiles, engines are in general hugely oversized to get acceleration, leading to greater engine friction due to larger engine size, and, much more importantly, to running at poor sfc due to low BMEP (I believe this is the correct way to express it). I have not yet seen any IC engine that can run at optimal or near-optimal sfc over the full range of engine loads and speeds -- not even close. Otto engines are simply not designed for it - particularly gasoline, spark-ignited, throttled engines running at stoich. The primary thrust of hybrids is, if you will, to try to mitigate this problem by stressing a smaller engine harder and getting power boost for the 10% of the time when it is required by using batteries, flywheels, ultracapacitors, etc.

The best answers I've seen to this problem are similar to those expressed in this link you provided:
http://www.swissauto.com/uploadfiles/EN_200056.pdf
namely, run higher BMEP, run lean, do EGR (perhaps), use VVT to try to approximate variable stroke and/or a Miller cycle, and run smaller and faster at higher boost pressure.

Yup. All of those. Add HCCI to run at detonation and thus close to ideal constant volume combustion (not to mention reducing heat loss and running at CRs approaching 50:1, at AFRs up to 40:1 or more), allow for real variable stroke in its purest form, use GDI partly to concentrate a richer area of charge but mostly to avoid blowing fuel out the exhaust in a two-cycle configuration, get rid of cranks to get real savings in engine friction, and run at really outrageous speeds while firing at every stroke to really get engine size down (I'm shooting for around 100 hp and 250 lb-ft. of torque, at least, at 0 rpm, from a 200cc engine).

Franzh--
Does that qualify as taking a "reasonably strong stand against the tried and true engine design?"

Sorry I'm not an engineer (so I'm told), but rather than waiting for something to "pop up," I've decided to try my hand at designing and building an engine anyway. Who knows? It might even work.

RE: The future of the engine as we know it

schwee--

Do you happen to have a website showing your engine?

I agree with what you said, but with low AFRs, I'm not quite sure whether this a really such a efficiency increasing measure, just because you obviously end up pumping a lot of air for 'nothing' and therefore increase your pumping losses.
I can only see the merits if it's the only possibility to realize a constant volume combustion.

I think another alternative could be if you had a miller cycle engine with an electric supercharger. Instead of using the recycled braking energy to propel the car, you could use it to supercharge the engine.
Why? It's less efficient but you can save weight because by using the electric energy to supercharge the engine you'd end up with about 4 times more power than you'd end up by using the electric motor to power the car directly. Also you could use a centrifugal supercharger which is inherently lighter and adiabatically more efficient than a roots supercharger. Since you can control the speed of the supercharger independent from the speed of the engine this concept would give you more control over the supercharger as well.

RE: The future of the engine as we know it

globi5-
Well, sort of..
You can try http://www.turbokart.com
Look under Projects, Project X.

That gives a general overview. The free-piston compressor/combustor (X combustor, is I think what my partner calls it) is the innovation.

You have a good point on the possibly diminishing retuns of ultra-lean mixtures. I'm basing my estimate of its value  on some experimental observations of a very similar engine (double-acting HCCI free-piston linear alternator) that has been built at Sandia by Van Blarigan and Aichlmayr. There's a good paper on it that's hard to find, but this is the gist:

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/merit03/28_snl_peter_van_blarigan.pdf

Hmmm-- the Sandia guys use an electric supercharger, (turbocharger?) too. That's a good thought. I'm not wild abut regenerative braking, though, partly because I think I've heard estimates of about 5% of a combined (or even city?) driving cycle being braking, plus the added weight and cost of batteries and motors, and what I think may be problems with rapid charging of batteries (though it seems I may be mistaken there.) But using a much smaller motor to supercharge the main engine to get more bang for the buck is a very good plan. My issue is with supercharging/turbocharging in general as an efficiency measure-- since you have to downgrade the normally aspirated CR to accomodate the forced induction, you're left with poorer efficiency when you're non-turboed. Ah - supercharging obviates that.

So I still haven't had time to plow through your links, but what is the gist of what the Wenko SAVE guys are up to? I see references to a "pressure wave supercharger" and "variable gas pocket intake" but no tables or diagrams seem available on that link. I don't quite understand how they propose to do spark-ignition lean burn, unless they use GDI (?) or swirling or something to richen the mixture near the spark plug (I think Mitsubishi is trying this). I also don't see how they're going to avoid deterioration of BMEP in a throttled engine at partial load. Maybe that's what the pressure wave supercharging is about.

What's your idea with the Miller cycle? Are you going to do it with valving?

RE: The future of the engine as we know it

On this of Franz:
>>>>Is the answer recovering the waste heat and totally transforming the thermodynamic capabilities of the fuel to usable energy?

What about cutting down on the waste heat in the first place? Who said that is a given? My take is that waste heat comes from combustion gases at high temperature sitting around "too" long in the cylinder, heating up cylinder walls, etc. Have 'em do their thing and get 'em out of there. Also, there are inherent problems of not recovering compression energy due to expansion stroke not being longer than compression stroke, etc., and blowing heat out the exhaust. So try to approximate a Miller cycle.

Obviously, you're right that no engine is 100% efficient. But what about 50%? 60%?

One question that has puzzled me is whether we are measuring the thermodynamic efficiency of a gasoline engine (say, 20%-25%) at optimal sfc or at partial throttle. I suspect that 25% represents optimal, and it deteriorates from there. So if you can bring up the part-throttle efficiency (I don't know, 10%?) to match the optimal sfc, you've gained a lot already.

RE: The future of the engine as we know it

schwee--

Thanks for the links. I'll read through it. (And 100HP for a kart is plenty. Btw talking about karts: What I find interesting is that there's still no maintenance free (or little maintenance) race kart package out there.)

Regarding the electric supercharger:
Because you use the electric motor to supercharge the engine you can get away with less weight. Yes you still have to charge the batteries or capacitors very rapidly and braking energy might not be sufficient to charge the batteries (especially if you don't do a lot of city driving) but you can also charge the batteries at partial load.
I'd use the miller cycle because you don't need to downgrade the CR. The miller cycle reduces the volumetric efficiency but allows the CR of the engine to be kept the same. The supercharger makes up for that loss. Example: The Prius (miller or atkinson cycle) has a CR of 13.5 and reaches an efficiency of 34% with a gasoline engine.

Regarding Wenko:
The Wenko guys are using a very small engine (360cc) to produce the power necessary. This way they can reduce the frictional losses and the weight of the engine. To generate the extra power they use a pressure wave supercharger, which compared to a turbo doesn't have a lag and is probably even more efficient. Actually Ferrari was testing it in a F1 engine about 20 something years ago.
There's no lean burn. It is simply a very small engine that can produce a lot of power only if necessary.

Pressure wave or comprex supercharger or wave rotor:
The pressure wave supercharger does basically the same as a turbocharger just without a turbine and a compressor wheel. To put it very simply: The exhaust gas compresses the intake gas directly.
http://www.egr.msu.edu/mueller/projects_waverotor.htm
http://www.grc.nasa.gov/WWW/cdtb/projects/waverotor/

RE: The future of the engine as we know it

(OP)
By nature and design, almost all gasoline spark ignited engines are throttled.  One of the biggest culprits for engine inefficiency are suction throttling losses.  Visualize pulling three (for a 6 cylinder engine) 3" diameter suction cups 3", 1200 times a minute, or 20 times a second.  That is roughly what an engine has to overcome at part throttle and 1200 rpm, or a slow speed or fast idle.  I agree that most of today’s engines operate at part throttle and that is certainly not the most efficient mode of an engines operation.

The idea of getting it out of there quickly bears some merit and is one of the reasons for variable cam timing.  What cam lobe profile and timing event works for idle is not exactly ideal for part throttle or full load.

As for the other posters, this thread is to discuss what engines may be like in the future.  I appreciate discussing new ideas and rehashing old ones, but be careful of posting self promoting designs.  As a patent holder myself, owning a patent simply means no one has done it before you, not necessarily that it works.  As a reference ONLY, no specific inference intended or implied, there are almost 300 patents on file of overunity engines, or engines that make more power than is inputted, also called the Perpetual Motion machine.

Franz

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: The future of the engine as we know it

Franz, good job clearing the air with reality here.  And the rest of yous guyz, the next significant breakthrough for SI is to minimize ring crevice outgassing and pumping loss.  Throttling via plate or valve actuation is not required, they are crutches to facilitate antiquated dare I say cheap to facilitate combustion strategies.  The real interest in plasma ignition is its capacity to produce enough btu's of heat to ignite...  um, we can call it dieseline for now. Lean direct injected gasoline mixtures, guided away from heat robbing flame quenching ring grooves and walls, on the order of 80:1 facilitate low load decel due to the inadequate heat to tick the engine over but enough to keep a nox reduction cat lit using combustion heat.  Part of the strategy involves throttling up to 50% egr in order to reduce excess heat loss.  Various aspects of this work have been in the lab at a few universities and at numerous oem consulting and component supplier locations for some time.  Thermal efficiencies in the peak neighborhood of 28% are the norm for SI, 39% for unthrottled is the best I have witnessed.  Others report up to 45%..  I dont beleive 45%.  Best case diesel is not that good in production.  The real advantage of all this is particulate free with closer to diesel efficiency without currently unmanageable CI cold start emissions.

In the future the SI and CI engines will have more in common and dieseline may become the norm.  This is not new news.  Why don't we have it yet?  The technology has to be more reliable and less costly than the reliable status quo AND without unacceptable risk.

To get there gasoline must be accomodated because a $900billion intl fuel station infrastructure is in place.

RE: The future of the engine as we know it

I still think downsizing and supercharging appears to make more sense than leaning the air fuel mixture. If you run an engine with small displacement at a given rpm and 16:1 AFR, an engine with double displacement needs to run at 32:1 AFR in order to consume the same amount of fuel. However the large engine has higher frictional losses, has to pump double the amount of air (or recycled exhaust gas), the combustion chamber has more surface (more heatloss) and the engine has more mass (more drag, reduced acceleration, mass distribution etc.). The only advantage of a larger naturally aspirated engine as opposed to a smaller supercharged engine is it's possibly cheaper to manufacture and maybe more reliable - or what is it? (If it's a miller cycle it doesn't need to have a lower CR.)

Another advantage of supercharging is that it can exploit the higher knock resistance of ethanol by simply increasing boost. (If someone wanted to switch between gasoline and ethanol).
Also an engine with a pressure wave supercharger has EGR basically integrated (no extra piping and valving necessary).
http://www.imrt.ethz.ch/research/projects/_details/index.cfm?id=24#

I wonder whether we'll ever see laser plugs in engines of passenger vehicles? http://transtech.anl.gov/v3n2/laser_ignition.html

Of course a very simple way to reduce pumping and frictional losses would be by having an extra economy gear (which seemed to have disappeared as well - my car runs 70mph at 3000rpm in 5th gear and I'm sure it could do the same at 1500rpm).

schwee-- Doesn't a gasturbine usually have difficulties  to react to rapid load changes? Or are there ways to solve this?

RE: The future of the engine as we know it

globi5:
I think that you will find that the Comprex Pressure-Wave Supercharger is now owned by Caterpillar.  I believe that they purchased the rights to the concept about 8 or 10 years ago, perhaps recognizing that the future would require EGR and high boost levels.  It turns out that while the Comprex will give you boost with some control over EGR, it is not capable of the pressure ratios that modern engines and certainly future premixed diesel engines require, and which can be had from (1 or 2-stage) turbochargers.

While the previous incarnations of the Comprex concept had the rotor belt driven at a fixed ratio from the crankshaft, the ultimate intent was to have the rotor drum driven by a variable speed motor, so that the system could be tuned for torque demand, gas temperature, and other variables.  

PJGD

RE: The future of the engine as we know it

globi5-
Sure, gas turbines are terrible in regard to rapid load changes. They also simply eat fuel at idle. Gas turbines are totally inappropriate for automotive use, as Chrysler found out in the 1960s. They have their limitations in other applications as well, which are not limited to their being expensive.

However, I'm not proposing a gas turbine. Maybe the easiest way to conceive of what I'm on about is to take a look at http:www.uspto.gov, and go to

http://www.uspto.gov/patft/help/images.htm#req

and download the free "alternaTIFF" viewer.

Then go to the home page, left column, Patent, search, then
Patent Number Search, and search on

1,785,643 (include the commas).

Click on "Images." You can't access the thing without downloading the Tiff viewer, or at least I couldn't.

Anyway, you'll find a 1930 patent for a rather ingenious system for using a linear alternator/motor to rotary alternator/motor system designed to smooth the oscillations in a double-acting compound free piston-gas turbine engine (whether it is HCCI or not is not specified -- it certainly could be).

Forget the smoothing system, which is actually what the patent is for. Focus on the engine. That's what I'm talking about (more or less). Check it out.

RE: The future of the engine as we know it

PJGD:
Do you have more information on plasma ignition? I don't fully understand its purpose, but it could be useful to me to know.

Of even more immediate relevance is lean direct-inject gasoline, which is exactly what I propose doing, I think. That is, what I really need is any information about developments in direct in-cylinder injection of homogeneous mixtures in a gasoline engine, at not especially high pressures but very fast (20,000 rpm equiv). Mixture range needs to be lambda 3 (say) to stoich. The reason I want this is so that I can inject fuel after my piston has already closed off my exhaust ports in my two-stroke.

When you say 80:1, 80:1 what? AFR?

RE: The future of the engine as we know it

sorry - that last query was for turbocohen, not PJGD.

RE: The future of the engine as we know it

Has anyone ever thought about adding a Stirling engine w/generator to recover (otherwise) waste(d) heat from the IC engine?

RE: The future of the engine as we know it

I don't want this to become a pressure wave thread, but I'd like to point this out.
Here's a link regarding Caterpillar and Comprex.
http://www.techbriefs.com/techsearch/tow/ab_caterpillar.html
Actually Comprex is not a new technology. Saurer a former Swiss-truck manufacturer which also produced the first turbocharged truck 1938 had been testing the Comprex supercharger 1969 already. ABB (former BBC) owned the trademark Comprex and must have sold it to Caterpillar. ABB still sells turbos for very large engines: http://www.abb.com/turbocharging. ABB also built large gasturbines but sold this division to Alstom.
schwee-- Again thanks for the links. I think I understand. By the way what's interesting is that the inventor lived in the same Swiss town where part of ABB and Alstom are still located. And if you look at the wave rotor, it actually works somewhat like a free piston just that the actual piston is missing and substituted by a gas layer. http://www.grc.nasa.gov/WWW/cdtb/projects/waverotor/

PJGD-- It appears to me that the Comprex drum is difficult to seal (compared to a shaft in a turbocharger), that the size of the drum and its cells is not really adaptable to different load conditions and that it is definitely more complex to control. But I don't see why the pressure ratio couldn't be as high as in a multi stage turbocharger as long as there's enough pressure in the exhaust manifold. In this case they are mentioning a pressure ratio increase of 3. http://www.grc.nasa.gov/WWW/RT1999/5000/5810welch.html
The exhaust gas compresses the intake gas in a cell directly, so I don't quite see what could limit this process as opposed to a single turbine or a compressor wheel which always have a limited pressure ratio. (I just try to understand it and I'm not claiming the pressure wave supercharger doesn't have a pressure ratio limit.)

RE: The future of the engine as we know it

SphincterBoy-- The stirling engine has a very low power to weight ratio. In order to recover the waste heat with a stirling engine you might require a stirling engine several times the size of the IC itself.

RE: The future of the engine as we know it

Schwee, that was afr.  Lean as in like dropping a match into an empty gas can.  A typical ignition system wont do it but a match will due to the adequate btu's.

RE: The future of the engine as we know it

sphincterboy-

Honda has received several patents recently for a "Rotary type fluid machine and waste heat recovering device for internal combustion engine". See US Pat. #6,681,738.  Don't know exactly what it is for.  

Also take a look at patents: 6,945,050  6,884,051  6,862,974

RE: The future of the engine as we know it

The Miller Cycle is not an independent  thermodynamic cycle.  It is a way of operating an Otto Cycle.  I prefer to call it the Miller toggle.  It requires two conditions.
    1.   The Otto Cycle
    2.   That the engine operate a significant amount of its time at reduced output
Given the above conditions the Miller cycle can be applied as a method of reducing engine power. This method of power reduction is more efficient than intake throttling because it reduces pumping loss.  An engine with its power reduced by the Miller method will use less fuel than the same engine with power reduced by intake throttling.
As for the future of the Miller Cycle, we probably will see more of this as long as we continue with Otto Cycle engines.  It will probably bring in variable valve timing.

RE: The future of the engine as we know it

I think the question we're looking at now is what is going to happen to the tried and true engines that currently exist vis a vis cutting edge materials engineering.

The internal combustion engine stands to benefit greatly from cutting edge thermoelectric technology... to the best of my recollection, almost all heat produced by an IC engine is lost to the environment, except for the minor amount used to heat the chassis during the cold weather months.  Since the thermoelectric hype died down greatly from what it was in the 50s, we should be wary that this technology doesn't go the way of the Stirling Engine.  

This is same with the electric motor, resistance in the windings escapes as heat... superconducting motors are 99% efficient at converting electrical energy into kinetic energy.  Currently it would be ridiculous to have a superconducting motor in a car... but our understanding of nanoscale engineering seems to suggest that within the next 30 years, superconductors requiring "minimal cooling" are possible.

RE: The future of the engine as we know it

Since it is entirely possible to design a 98.4% efficient electric motor that is suitable for vehicle use, I don't see why we are waiting for superconductors, unless that last 0.6% has some importance I have yet to understand.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: The future of the engine as we know it

(OP)
If I am not mistaken, its not especially difficult for the motor side, but the batteries and controllers are the biggest stumbling block.  The simple lead acid battery works great but is heavy, lithium ion is lighter, but lower amperage and other problems, and a multitude of other battery options.
This is where the next technology hurdle lays in hiding.

Franz

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

RE: The future of the engine as we know it

Its true we can produce very efficient motors without superconductors (99% efficiency is actually 99.9% btw)... I am not sure the limitations of this though.  Perhaps the 98.4% efficient motors are laptop hard drive motors as opposed to 200 HP car motors (these do tend to heat up a BIT more at least), I am not entirely certain.

It seems to me that the prevailing question here is not the engine design but rather the fuel source.  Of course we want to use a fuel source that is efficient in terms of energy density because our cars are ridiculously heavy to begin with.

If it were a viable solution to redesign the car from the ground up what method of locomotion would you end up using?  Obviously you could create the "Popular Mechanics Gas Turbine Powered 3 Ton convertible" we were supposed to all be driving this millenium.  To me it seems far more sensible to make a super light car that has a small engine and as high efficiency as possible regenerative braking techniques... this way the energy density of our fuel sources would cease being the key issue.

Im now really getting into a realm where I have much less understanding now, but theoretically if you have a 99% efficient motor and a similarly efficient method of recovering the energy through breaking, battery banks would be uncessary... you could have a single backup battery and run the car off a very large capacitor! :P  

RE: The future of the engine as we know it

How about the 2 stroke?  I believe the Orbital engine company has some running in cars for evaluation. There fuel system seemed to be quite good.
 A 2 stroke certainly has less moving parts, meaning less friction, less weight, Maybe we should look at the uniflow 2 stroke again, like the Detroit Desiel, but with some modern design and technology thrown at it to see what bounces!

Ken

RE: The future of the engine as we know it

Hi-
      I disagree with the assertion that Stirling engines have a very low power to weight ratio.   While there are plenty of issues with Stirling engines, the power to weight ratio issue was overcome long ago by pressurizing the crankcase.   GM, FORD and AMC had Stirling engine programs some years back.  The FORD & AMC programs reached the point where the performance of a car powered by the Stirling engine was nearly identical to a car powered by their stock IC engines.  See  http://www.stirlingengine.com/faq/one?scope=public&faq_id=1

       On  Two-Stroke engines:  The Detroit Diesel two stroke engines had the piston rings pinned so that they could not rotate.  This lead to, in their case, high oil consumption and high particulate emissions.   Perhaps this difficulty could be overcome, but it would take some engineering effort.

RE: The future of the engine as we know it

"Perhaps the 98.4% efficient motors are laptop hard drive motors as opposed to 200 HP car motors (these do tend to heat up a BIT more at least), I am not entirely certain."

No, I have designed, assembled and used a 98.4% efficient electric traction motor in a vehicle that has completed in excess of 15000 km on public roads.

Electric motor efficiency is NOT the problem. Batteries and energy source are. If we could eliminate the current fleet, or segregate electric transport from the current fleet, then electric commuter cars are feasible now. Basically it is not a problem I worry about, at some point someone will bite the bullet, and make the necessary changes, and it will happen. Then everybody else will say, oh that was not too hard, and join in.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: The future of the engine as we know it

An internal combustion has the inherent advantage that it doesn't really need a separate system to generate and dissipate heat to the extent a stirling engine does. (The heat generator is part of the engine and the combusted air dissipates most heat automatically.)
A stirling engine has to sepearte hot and cold side of the engine. An internal combustion engine doesn't, which means it requires less volume (less mass) and it can reach higher temperatures, since its parts are not constantly exposed to extremely high temperatures.
For the above reasons I have difficulties to believe that stirling engines will ever reach the power density of an internal combustion engine.

There are engines for passenger vehicles (not research or race engines) reaching well over 100HP/l. So far I haven't seen a stirling engine with a similar power density.
Unfortunately this link doesn't contain any specific information about power and mass of the stirling engine powered cars used in research: http://www.stirlingengine.com/faq/one?scope=public&faq_id=1

RE: The future of the engine as we know it

Peltier (or Seebeck generators) cooling elements are currently hardly even used to cool PC processors. Eventhough it definitely better than having all these noisy cooling fans or water tubes (Apple G5). So as long as there not even powerful or efficient enough to cool PC processors, I doubt that they will be useful to gain energy from exhaust systems.

RE: The future of the engine as we know it

globi5 -  I agree that the stirling engine has some significant disadvantages when compared to an IC engine.  It also has some advantages, such as higher theoretical cycle efficiency.

      The Ford stirling engine project used a Ford Torino (a big car, not a small car):   "The  Ford Torino swashplate Stirling car  engine was based on a 4-65 engine pressured to 225 Atmospheres, and 50kw power at 5000 RPM. "  ( see http://www.rotarystirlingengines.com/featuredengines.htm ).

      Note the high pressures used by the Stirling engine.  I think that the  working fluid was hydrogen.   
 
      The 50 Kw power from the Stirling engine was more useful than 50 Kw from a four stroke IC engine because the stirling engine has a power stroke on every revolution.  The four stroke IC engine only has a power stroke every other revolution.

       

RE: The future of the engine as we know it

"The 50 Kw power from the Stirling engine was more useful than 50 Kw from a four stroke IC engine because the stirling engine has a power stroke on every revolution.  The four stroke IC engine only has a power stroke every other revolution."

Please justify that remark. What do you mean by useful?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: The future of the engine as we know it

      On  Two-Stroke engines:  The Detroit Diesel two stroke engines had the piston rings pinned so that they could not rotate.  This lead to, in their case, high oil consumption and high particulate emissions.   Perhaps this difficulty could be overcome, but it would take some engineering effort.

I havent had a huge amount to do with the engines to know there shortcomings.  But yes with some engineering of the modern kind, who knows what could be achieved.

On electric, There are some big gains being made in Lithium Polymer batteries, in a few years they just might be practical for all electric transport. Let the Sparks fly!!

Ken

RE: The future of the engine as we know it

Please justify that remark. What do you mean by useful?

Aw, c'mon Greg.  Obviously if the power comes out every fourth stroke, you'll have to use some sort of high-efficiency rotating mechanical energy storage device to absorb the surges and fill the troughs.  Some kind of big spinning disk, perhaps...    ;)

RE: The future of the engine as we know it

Hmm, I wonder if we could invent a 100% efficent device to do that? I think I'll patent it and call it a big wheel that flies round, or, possibly, a Fly Wheel.

Any takers?

Cheers

Greg Locock

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RE: The future of the engine as we know it

Sorry Greg, Im keeping my money for that gram of anti-matter ive been promised!

Ken

RE: The future of the engine as we know it

Heard about them that hunerd percent efficient flywheels before..  Theyre made out of unobtainium right?

RE: The future of the engine as we know it

Greg-

    Here's my justification for saying a power stroke every revolution is more effective than a power stroke every other revolution:   smaller, cheaper, lighter flywheel.    Simpler, cheaper, and lighter transmission.   

     Also, a power stroke every revolution also results in lower peak torque on the crankshaft (for the same brake torque) than a power stroke every other revolution.  So the crankshaft can be smaller and lighter on a Stirling engine than a four stroke IC engine.

     Don't misinterpret what I am saying:  the Stirling engine has lots of issues.  But it does have some niche uses.

      Some company in the US recently started manufacturing  five KW  Stirling engine gen sets to run off poor quality natural gas  (natural gas that damages IC engines).   I suspect that the company will sell quite a few of these.


j2bprometheus

RE: The future of the engine as we know it

(OP)
Hmm, a flywheel that runs in a total vacuum, suspended on superconductive electromagnetic bearings, never powering any load (no drain).

Hey!  This may just work!

eng-tips, by professional engineers for professional engineers
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RE: The future of the engine as we know it

Two stroke or four stroke is only really relevant where there is only a single working cylinder.

With multiple cylinders you can have as many firing strokes per revolution as you wish with either.

RE: The future of the engine as we know it

Warpspeed-

       Adding more cylinders adds more cost.

       The proper comparison is single cylinder to single cylinder   or  eight cylinder to eight cylinder.

j2bprometheus

RE: The future of the engine as we know it

BMW's steam assisted drive:
http://www.greencarcongress.com/2005/12/bmw_developing_.html

One thought: If the steam engine was charging batteries or condensators via a generator, the waste heat could be used to supercharge the engine with an electric supercharger, therefore allowing a much smaller, lighter engine with better fuel efficiency at low power settings (which could possibly offset the extra weight of the steam engine with generator).

Of course and as always the question will be: Are the added costs justified?

RE: The future of the engine as we know it

What happens to a flywheel when you hit a wall going 65 mph? I can see it breaking off its shaft and flying out of the car or breaking up into shrapnel.

I've given thought to the use of compound turbocharging and the use of a stirling engine powering an alternator to charge batteries.

The compound turbocharger doesn't really seem to work because as I understand it you need to compress the air going into the engine to be able to extract the power from the exhaust, or else the turbine at the outlet produces backpressure in the engine (I could be greatly mistaken and tell me if I am because I'd like to know more). So therefore you can only really generate power by using the blowby relief valve when you're finished exerting the engine and you have too much boost, this is fine for a mining truck or a stop-and-go vehicle, but not much use on the highways at sustained speeds and throttle settings because your extra boost goes away.

Alternatively, you can use a stirling engine to convert the waste heat from the exhaust and the block to power a generator to charge batteries or drive a flywheel (read the first part of my post as far as worries for the second option go), the advantage of which is that the engine is always generating excess heat, and once the batteries are full you just divert the electric power to supplement the IC engine's power by driving electric motors. the disadvantage is the added weight of IC engine + stirling engine + electrical motors.

Diesel hybrid seems to be the way to go in the near future tho.

another interesting engine can be seen here:

www.microturbine.com

they aren't a miracle engine or anything else, and being turbines they have fuel consumption problems. the big advantage they have is that they only have one moving part, but there is no contact between moving parts whatsoever so they simply don't wear out, the only maintenance required is an air filter change every so many hours. they're already being used to power buses. You end up with a vehicle that could run for many hundreds of thousands of miles without need for a tuneup or oil change. The use of charging stations at home would also help the hybrids.

RE: The future of the engine as we know it

Scania has been selling a turbocompound system on its trucks for a while now. http://www.scania.com/products/trucks/Technology/Scania_turbocompound/how_does_it_work.asp
(If it wouldn't work they wouldn't sell it.)

Not sure whether this has even been questioned, but BMW's turbosteamer (as opposed to the turbocompound system) doesn't increase backpressure.

I wonder whether BMW's mini steam turbine has a higher power to weight ratio than a stirling engine. (There must be a reason why BMW's engineers didn't come up with a stirling engine.)

RE: The future of the engine as we know it

Interesting, I wonder if the flywheel can redirect it's energy back to the compounding turbine, that would allow it to maintain it's rpms and thus avoid backpressure, and if so the engine can spin up the compounding turbine when starting up so that avoids it as well. But, this isn't something you can do with an electric turbocompound unless you want to use up the energy you already put into the batteries to spin it back up. thanks for pointing that out

as for stirling engines, the best gas you can use is hydrogen, and there are big problems with keeping it inside the engine since it'll leak out of anything. I can see a steam turbine being easier to maintain over time.

I had heard about this following link before, CAT and john deer have been working on an electric turbocompounder.

I stumbled across this link while looking for some up to date info on the topic so you might find it very interesting, the pdf document is contained in there but I'll provide the link to that one as well.

http://www.osti.gov/fcvt/deer2005/deer2005wkshp.html

the specific link is here

http://www.osti.gov/fcvt/deer2005/Vuk.pdf

very interesting stuff!

RE: The future of the engine as we know it

Power to mass ratio for stirling engines

http://www.cirps.it/old/attuali/interna_19.htm

3.5 kW 200kg (complete installation including burner), say 17 W/kg

However, NASA reckons 15 W/kg max, admittedly for space qualified gear.

Rather interestingly none of the Stirling engine sites I found that claim improved power to weight ratios actually quote numbers, so I think they are shuffling their feet, whistling, with their fingers crossed, hoping I'll go away.







Cheers

Greg Locock

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RE: The future of the engine as we know it

Hi-

    The  brake thermal efficiency of the stirling engine that GregLocock  found is terrible --->  less than 10 %  -----   must have a poor regenerator.   

        Admittedly, they are using the rest of the heat to make hot water.    But the electricity is more valuable than hot water.


j2bprometheus

RE: The future of the engine as we know it

Any additional turbine will increase backpressure. As does a muffler, just without doing any useful work.

RE: The future of the engine as we know it

Yes, but a flash boiler could extract a lot of otherwise wasted exhaust heat with very little added back pressure, and muffle the exhaust at the same time. The steam supply  would go up and down with engine power with very little lag, I suspect few if any additional control systems would be required to make it work.

Generating high pressure steam is an absolutely brilliant idea. Anyone know what sort of steam expander they use ?  From the rather poor quality picture in the press release, it looks like two internally geared rotors of some type. A screw expansion engine perhaps ?  What a wonderful idea.

RE: The future of the engine as we know it

A company called STM Power (http://www.stmpower.com) has a 55 kW stirling module that weighs 4000 pounds (as stated in the newsweek article linked to their page) so you get around 30 W/kg. A tenfold increase in power output. These units are apparently for sale already and have been shipped to customers.

Even then a unit weighing 100 kg only makes 3 kW or nearly 4 HP, nothing compared to the steam thingie. I like that idea.

RE: The future of the engine as we know it

In keeping with the original theme of this thread I want to restate that I think the IC piston, rod, crankshaft engine will be the prime mover for suface transportation for the forseable future. Given the amount of energy that is lost to the exhaust and cooling system provides a source of potential recovery. Turbocompounding seems to be the most logical choice for exhaust energy recovery. The Wright Cyclone TC3350 is well documented showing about 20% improvement in BSFC #s and power increase. I think the Scania effort is compleatly backwards. Turbine driving the crank should be ahead of the turbo supercharger. I suspect the arrangement they offer was the most cost effective method of implementing it on their existing powerplant arrangement. The data claims that they are getting about 5% higher BSFC #s and power at first glance seems a little on the low side but there is less energy lost in the exhaust with a diesel vs a gasoline fueled engine to begin with. I also think that generating steam from the heat lost in the cooling system has a lot of merit. Steam spins turbine linked to the crank or final drive line and use the radiator as a condenser. I only became aware of the BMW effort a few days ago via the link provided by GLOBI5. It doesn't appear that they are giving any data about fuel economy improvements or power levels. I think there is a 20%-30% (gasoline fueled engine) improvement available there. Not sure at this time how to address the ice problem in sub freezing climates. Implementing one or both of these methods should keep the IC engine around long enough to power the hearse that delivers me to my final resting place.--------Phil

RE: The future of the engine as we know it

Forgive me I over looked the 15% fuel economy gain from steam stated from the BMW link.-------Phil

RE: The future of the engine as we know it

At least as far as I know the Wankel engine has hotter exhaust gases than a conventional gasoline engine. The Mazda RX-8 actually has an electric air pump forcing air into the exhaust for post combustion: http://www.rotaryengineillustrated.com/renesis/renesis16popup.jpg )
So the steam assisted drive in conjunction with a rotary engine should be more effective than with a conventional engine. Maybe this could help make Wankel engines more popular - especially since the Wankel engine is supposed to have a higher mechanical efficiency (no valve train)?

RE: The future of the engine as we know it

'found a picture of a stock RX-8 with an aftermarket exhaust: http://intinsifi.com/transmit/flames.jpg
(It at least appears to lose some heat. Note: there's no crazy exhaust fuel injection or something).

RE: The future of the engine as we know it

Wankel thermal efficiency is quite low due to the higher surface to volume of the combustion chamber.  The Wankels advantage is power to weight and packaging size.  A derivative of the Wankel makes a decent supercharger though.

RE: The future of the engine as we know it

The higher surface to volume ratio is one reason why the thermal efficiency of the Wankel is lower - the other is incomplete combustion due to the moving and slim combustion chamber (that's why the air pump is necessary).
However some claim that at high loads a Wankel is more efficient than a conventional gasoline engine. I read somewhere that one of the reasons why Mazda's 26B won LeMans 1991 was because its rotary engine was more efficient than the turbocharged conventional engines of the competition (fuel was limited). Maybe someone has more info about this?

If the steam engine would drive a supercharger, the surface to volume ratio would go down and the power to weight ratio of the whole system would be increased or at least be unchanged.
This axialflow supercharger only weighs 11lbs.
http://www.axialflow.com/products.html

RE: The future of the engine as we know it

As far as I know the main reason why the mazda 26B won the LeMans race was because the only thing it ever needed to stop for was gas and tires. The truth is, wankel engines get horrible gas mileage, even the RX-8 with it's supposed improvements gets worse gas mileage than a similarly powered car with a normal reciprocating engine. (the typical comparison is with the nissan 350Z)

by the end of the race, the engine in the 26B had virtually no wear, whereas a normal engine would probably be in moderate to poor shape since they're made to last one race only before a rebuild.

RE: The future of the engine as we know it

The 26B won because its reliability as well. But I remember reading somewhere that it had a low fuel consumption compared to other race cars.
Here's a link: http://www.monito.com/wankel/lemans.html Couldn't find the fuel consumption in g/(kW*h) though.

A passenger car is driven 95% at partial throttle and a race car 5% at partial throttle. If we are comparing fuel consumption of passenger vehicles we really compare fuel consumption of these cars at partial throttle.

Unfortunately there isn't a lot of fuel consumption data of race cars available.

RE: The future of the engine as we know it

well with the link you gave, the 787B gets 4.31 miles per gallon. doing 213 km/hr average

I've estimated the fuel consumption of the audi R8 at around 5.8 miles per gallon under wet conditions with a pit stop after 200 miles (exact mileage unspecified) and an 80 gallon tank of gas. this data is all I've been able to find for any other car other than the 787. the track was wet for at least part of the time on this run so it's slower than normal, but then again the fuel consumption is a very conservative estimate. Also, the R8 won the best fuel consumption award at the 2005 lemans race (which it won) so it's not a fair comparison.

any racers know a '91 fuel consumption figure?

RE: The future of the engine as we know it

I thought one of the main reasons Wankel-engined vehicles do well in competitions is that nobody can agree a way to compare them with reciprocating engines in terms of capacity.  And since racing bodies generally classify vehicles based on their swept volume, their choice of that definition for a Wankel engine dictates whether the vehicle is super-competitive or a dead loser.

Remember bike racing in the late eighties? Norton caned everyone when they played the Wankel card.

RE: The future of the engine as we know it

In this article BMW claims that their 'turobsteamer' concept regains more than 80% of the heat in exhaust gases.
http://paultan.org/archives/2005/12/11/bmw-turbosteamer/
Besides they also transfer some of the heat energy in the cooling system into mechanical energy.

If this indeed works as advertised the thermal efficiency of an engine is less important and mechanical efficiency, power to weight ratio play a more important role (which could make Wankel or gasoline engines compared to Diesel engines more attractive).

The swept volume of a Wankel is twice the chamber volume. If the Wankel was operated as a simple air pump it would displace twice the chamber volume. (I don't see why there's much disagreement about this, but I do understand that they try to limit the options in order to keep it competitive - if one has an engine that is far superior, the race is boring.)

RE: The future of the engine as we know it

One of the advantages of a wankel is its low octane requirement.  Plenty of them race with 85 octane fuel.  High octane fuels cost power and the generally lower btu per volume yeilds less mpg's.

Years ago GM damn nearly went to production of a large vehicle wankel but smog and poor efficiency at the time killed it.

RE: The future of the engine as we know it

dalcazar, I can give you a couple of figures based on my memory only as I no longer have the records from the 80's.
I can also give you one current figure for my 1380cc Mini Cooper race car.

1594cc Lotus Cortina twincam ~165 hp at the wheels---race weight of 2060 lbs., car and driver---Riverside Int. Raceway lap times 2:05 long course and 1:39 short course (this car retired three lap records at RIR)--- 10 gallons of race fuel per hour...
Same car with 139hp at the wheels 2:09's and 1:42's same tracks and ~9 gallons per hour.

<500hp tube frame IMSA Pantera RIR long course 24 gallons per hour...sorry I don't remember the weight, but it was pretty light tube frame and fiberglass...it was not my car, I was the "fuel guy" in the crew and I just ran the 'dump cans'.

1380cc Austin Cooper @ 110.45 hp at the wheels, 1730 lbs. race weight car and driver.
Based on three two hour races at Willow springs from 2003 to 2005... 7.2 gallons of Sunoco 110 per hour.

My only experience with a rotary engined car was in 1973 at the FIA  Six Hours of Mexico City race where we were pitted near a little yellow Mazda sedan from El Salvador...it was incredably loud and used fuel like a NASCAR stocker!!!

Rod

RE: The future of the engine as we know it

Great thread guys.  I haven't read the whole thing..but here's my $0.02.

Has anyone talked about valving technology?  What I'm thinking is that a variable electronically controlled valving scheme could drastically change how the IC engine operates and how we "humans" can use the power.  

From my IC engines in college, the valving has always been based on a cam lobe, which has physical constraints that an electrically operating valve would not have.  I know there has been some shots taken at electronic valves, but maybe the technology is not there yet. Can an almost instantaneous valve opening/closing event really change what we know about IC engines?  I think so.  So far all of our CFD analysis has been done on realatively slow opening and closing of the valves. The physics may not change, but the operating efficiency and overall power characteristics may very well change. Sorry if this leads to another thread.

I agree with the basic assumption that it will take a very distruptive technology to unseat the IC from popularity.  But like quantum computing, it's just a matter of time, before binary computing goes by the wayside and quantum computing takes over.  I may go to the grave in an IC engine hearst..but my son or grandson may not...

RE: The future of the engine as we know it

Already available, and I think, about to be put in a production car. Delphi make one system.

The trouble is that it only offers an incremental improvement in real life performance/economy, at a quite remarkable cost. I suspect that a conventional, somewhat larger, engine could match the electronic valvetrain engine for torque, max power, and economy, by using a cam optimised for part throttle economy, and using sheer volume to get the other performance measures. Well, we'll see.

Cheers

Greg Locock

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RE: The future of the engine as we know it

EVT has been around the block a few times and although it is useful for lab work it is not practical for the road yet.  yet.
The armature motion control is but one issue that has been resolved but cost and risk/benefit is not attractive..  yet.

One of the main advantages is less pumping loss and reduced oil vaporizing from exposure to valve gear for lowered HC's.  Yes the digitally calibrated actuation of inlet and exhaust with burping features are attractive but variable systems are damn near as good at a fraction of the cost and risk.  When 42v ststems become commonplace then the cost will come down a bit but I still do not want to own the first few generations of vehicles with evt.  I think it makes more economic sense to use an advanced diesel hybrid.

RE: The future of the engine as we know it

Electromagnetically controlled valves give one the complete freedom when what valve to open or close (which is a tremendous advantage). However, I have difficulties to believe that electromagnetically controlled valves can be faster than mechanically controlled valves.

I was briefly involved in a feasibility study of a powerful electromagnetically controlled fibre rewinder and it couldn't reach the switching speed of the mechanically controlled rewinder.

RE: The future of the engine as we know it

Formula 1 uses electro-hydraulic valve actuation systems and they exceed 20,000 RPM. Will that be sufficient?

No matter what how they're actuated, poppet valves are far from optimal. Coates' spherical rotary valves have been in development for the better part of a decade now but I haven't seen any promise of production yet.

Look at this design:

http://www.revetec.com/
 in a tubocharged CI configuration this would be an intriguing powerplant.

RE: The future of the engine as we know it

Actually electro-hydraulic could be faster than electro magnetic actuation, since an electrical valve only needs to travel a very short distance and instead of electromagnets piezos can be used.
Still still I don't necessarily see why a hydraulic linkage should be faster than a solid mechanical linkage.

So far I've only read of F1 engines with traditional camshafts and poppet-valves on 'air-springs'. Which F1 engines run on electro-hydraulic valves? Do you have more information?

RE: The future of the engine as we know it

"Formula 1 uses electro-hydraulic valve actuation systems and they exceed 20,000 RPM. Will that be sufficient?"

Rubbish on two counts. First they use pneumatically sprung poppet valves driven by conventional camshafts, and secondly they do not exceed 20000 RPM by design.

Cheers

Greg Locock

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RE: The future of the engine as we know it

Forgive me; the gearbox, not the valvetrain is electro-hydraulic. I did however watch the telemetry readout spin above 20,000 RPM with my own eyes.

RE: The future of the engine as we know it

Which race? Which car? Schu was topping out at 19000 rpm in the early part of this year,

http://members.optusnet.com.au/greglocock/cepstrum.htm

and none of the teams, so far as I know, were claiming 20000. With the V8s this coming year they might see 21000, according to the rumour mill.



Cheers

Greg Locock

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RE: The future of the engine as we know it


From the link on Greg's site:-
http://f1.tottoro.hu/2004/01_australia/19_qlf2_mschumacher.avi not found! It's a shame really. If you still have the sound file, could you post it somewhere please Greg?

(From the FIA website, regarding Formula One 2008 regulations)

ARTICLE 5 : ENGINES
5.1 Engine specification :
5.1.1 Only 4-stroke engines with reciprocating pistons are permitted.
5.1.2 Engine capacity must not exceed 2400 cc.
5.1.3 Crankshaft rotational speed must not exceed 19,000rpm [This figure may be increased to 20,000rpm in
consultation with the competing teams].

5.1.4 Supercharging is forbidden.
5.1.5 All engines must have 8 cylinders arranged in a 90º “V” configuration and the normal section of each
cylinder must be circular.
5.1.6 Engines must have two inlet and two exhaust valves per cylinder.
Only reciprocating poppet valves are permitted.
The sealing interface between the moving valve component and the stationary engine component must be
circular.

RE: The future of the engine as we know it

Hmm, that was 2 computers ago. I'll have a look.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: The future of the engine as we know it

I attended a tribology conference last year and one of the presentations was on using a liquid who’s viscosity could be greatly changed in the presence of a magnetic field. This was used in a type of hydraulic lifter so effectively the valve lift could be reduced, the maximum lift was governed by the cam.

RE: The future of the engine as we know it

It might not belong here, but here is another 'new' engine concept that some of you may be interested in
www.pivotalengine.com
I dont think I have seen it on here before but sorry if its a re-post

RE: The future of the engine as we know it

I'm not sure I understand how this engine has advantages over existing clean-burning two-strokes incorporating direct in-cylinder injection. I can see the argument for eliminating piston rocking, but it seems there are sharp, square corners that need to be sealed. I think that's one of the reasons a rotary has problems with both wear and fuel/oil consumption. The engine also still uses the crankcase for pressurization-- a sure loser, in my book.

On the claim of "additional savings from not having oil changes factored in"-- does this mean oil is put in the fuel?

Then, any site that talks about hydrogen as a viable fuel source and doesn't know how to use the possessive "its" immediately raises my suspicions.

RE: The future of the engine as we know it

The Bourke Engine look like better (much simpler) solution then pivotal engine. In the bourke engine piston do not rocking, oil is totally separated, it is 2 struck so it guaranty high power density.  

RE: The future of the engine as we know it

Also with the pivotal engine the 'active' cooling of the piston must reduce the engines efficiency, while the combustion chamber shape is also far from ideal. I like how the picture of the engine in a car does not show any of the other parts required to get significant power out of this engine such as the four rather large expansion chambers. In actuall fact this engine is very similar in size to a subaru engine  

RE: The future of the engine as we know it

Disruptive engine and drivetrain technology requires clean sheet designing. First you must understand the drive cycle. For most city driving people, this is stop and go at lower speeds. The actual torque/HP required at the wheels is not well known. Regenerative braking is a must. This is difficult because braking energy is 2 to 3 times accelerating energy for a shorter time. Most variable speed electric drives are under 80% efficient average over their rpm range during regeneration, and under 87% efficient average over their rpm range.
Since burning fuel releases heat, converting that heat to power is a simple, yet complex problem. The pressure and expansion from combustion in gas and diesel piston engines is used to rotate a crank, swash plate, or rotor. All these current systems have an intake stroke equal to the power stroke. Sterling engines and steam require heat to be to be transferred through metal walls.
The difficult problem with expanding a gas is the pressure becomes lower the longer the expansion takes place, so extracting that energy becomes more difficult and less attractive. (Lower power to weight ratio)
My solution is to decouple each cylinder, so only the number required to propel the vehicle are firing, and have them run at the optimum piston speed. Then to extract maximum heat to expansion, shortly after the fuel is burnt, inject water to provide a more efficient expansion fluid. This requires the power stroke to be longer than the intake and compression, so a linear engine is required. It seems the pumping losses for a 4 stroke are less than a 2 stroke, so this is the direction I’ve chosen.
Having built and tested the basic design, the next problem is converting this motion to wheel torque. The required energy is high, and the densities for mobile application make hydraulics the best choice, yet there are neither hydraulic valves, or motor designs are available to meet these requirements yet.
For more information visit:
http://www.dehyds.com/

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