increasing torque without any big modifications
increasing torque without any big modifications
(OP)
Hello. I wanna ask, how increase engine torque without increasing displacement, compression ratio, and fuel consumption? Or how new engines increase fuel efficiency and power, when compared to older egines? I know, that new engines have higher CR, ecu controlled fuel injection and ignition timming, better designed combustion chambers, variable cams and intake manifold, but that is enough or there is something i missed?





RE: increasing torque without any big modifications
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
Your thread title includes "... without any big modifications", but going from an old carbureted points-ignition pushrod Chevrolet small block that was designed in the 1950s to a modern fuel-injected twin-cam pentroof 4-valve-per-cylinder with variable valve timing and with intake and exhaust systems that were designed with the aid of computer software that no one even imagined when the Chevy small block was designed ... is a rather big modification.
RE: increasing torque without any big modifications
http://www.amrca.com/tech/tuners.pdf
" number of power strokes/minute "
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
- Steve
RE: increasing torque without any big modifications
Thank You for answers :)
RE: increasing torque without any big modifications
Exhaust systems were often restrictive in the bad old days. Nowadays, they are usually pretty well chosen.
Changing carb to fuel injection is a "big modification". It generally involves replacing the intake manifold with one of a completely different design. A manifold for multi-point fuel injection need not be designed for eliminating "puddling" or optimizing cylinder-to-cylinder fuel distribution. Manifolds for V8 engines nowadays look nothing like the traditional intake manifold of the (carbureted) past.
There is no magic involved here. If you get a certain amount of air into the engine, that calls for a certain amount of fuel, and the engine will want a certain ignition timing to run best. If you want to make more torque at a certain engine speed, you have to get more air in. Nothing you tinker with on your computer can do that. It's determined by hard parts ... piston displacement, ports, valves, camshafts, etc.
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
tbuelna - how much ecu remap can reduce engine reliabilty, if ignition timing isn't too much advanced? :)
RE: increasing torque without any big modifications
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: increasing torque without any big modifications
Improper engine tuning can make an engine go kaboom in a big hurry under the right/wrong conditions.
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
This would get you started in the right direction.
http://www.amazon.com/Scientific-Exhaust-Systems-E...
RE: increasing torque without any big modifications
When the exhaust valve opens, a huge pressure wave is sent throughout the pipe. That pressure wave travels at the speed of sound. When it reaches the atmosphere (or an area increase large enough to simulate one), this pressure wave is reflected as a lower pressure wave (think vacuum). This lower pressure wave travel also at the speed of sound towards the cylinder (yes, against gas flow). When it reaches the valve, it then reflects again as a high pressure wave, but lower than the first one. And this process keeps going on until the pressure stabilizes through the pipe. Of course - in an engine - the pressure never quite stabilize because of the engine cycle.
Because we know the speed at which the waves travel, the trick is to tune the length of the exhaust pipe such that the low pressure wave arrives at the cylinder at a moment where the exhaust valve is open to facilitate the scavenging process. The wave can return in a following cycle or even at another cylinder valve (when there is exhaust collector).
You can see this as the molecules' way to communicate between each other. When the exhaust valve opens, the gas molecules are saying: «We're getting out, make space for us!». Of course, the molecules on the other side of the valve can't really move so they just pass the message along the pipe until it reaches an open end. At this point, the molecules are saying: «We found free space, keep coming!» But that message has to go back to the cylinder where the high pressure is.
The same process is used to tune the intake length, except that a low pressure wave is sent when the intake valve opens («We found free space, send more molecules») and it is reflected as a high pressure wave going toward the cylinder («We found a bunch of molecules; they're coming!»).
Search for «pressure wave» and «fluid dynamics». This article is a good start.
RE: increasing torque without any big modifications
If we want the pressure wave to arrive at a certain crank angle after the valve opening (Δθ) and we know the rpm (ω), then the time that is available is Δθ/ω. The pressure wave will travel at the speed of sound (v) through a length of pipe (L). The time taken to do that is L/v. Both these times must be equal, so:
L = (Δθ * v) / ω
So we can see how when the rpm at which we want to tune the exhaust increases, the length of the pipe must decrease (and vice-versa).
This is extremely simplified as the speed of sound will vary throughout the pipe and with many other complex factors, but the principle remains.
RE: increasing torque without any big modifications
One set point is particularly important for engine life, -the rev limit. But, also gear shift points.
Other changes are dubious as to their benefit. Most emissions settings are not in play under WOT conditions. The manufacturer's settings are probably best. Unless... you change other things, like the camshafts, modify the heads, exhaust, etc. Then, your driving style will likely hurt engine life and the mods will hurt your wallet when the manufacturer refuses to make repairs under warranty.
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
je suis charlie
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
Your crank shaft requires a lot of torque to spin it. If you can reduce weight there, you reduce a big parasitic. Otherwise you can change your timing to increase BMEP.
Oh wait, you said without using "more" fuel. Use fuels that have higher energy density, and then change your timing. Thats not against the rules, is it? lol Your only options are strictly BMEP related unless you go after your crank shaft with a grinder. This includes evacuating spent fuel charge more effectively
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
You will lose power if you go to port EFI. Every car lost power when they switched to port injection EFI in the 80s. I have a 1999 mustang GT that I converted to run a carburetor and it gained 10% on the dyno with the same stock EFI intake that it was using EFI with. The igntition map was also identical to stock. Then I changed the ignition map and gained another 5% in power. So my carburetor conversion and ignition remap gained me 15% rear wheel horsepower. If you have EFI and a modern 4 barrel carburetor running the same air fuel ratio, the carburetor will usually make more power. They have an intercooling effect on the intake charge as well as significantly better fuel atomizing. Even Throttle Body Injection makes more sense for peak performance than port fuel injection. However, port EFI is ultra easy to dial in and get it running at its full potential. Carburetors take skill to tune correctly, and you have to re-tune them when conditions change.
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
The only race cars that still use carburettors are the ones that are mandated by rules. The rest use multi-point fuel injection. I guess they should all go back to carbies?
je suis charlie
RE: increasing torque without any big modifications
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
Takes only ONE counterexample to disprove that, and it's a vehicle that I owned a (carb) example of.
Toyota 22R carb, 97 hp (1981-1990)
Toyota 22RE EFI, 105 hp (1983-1984) and there was a redesign in 1985 that increased it even further. Most of them were 114 hp (1985-1997). The 1983-1984 carb versus EFI models are directly comparable and were available in the same vehicles (base models got carb, higher models got EFI) ... carb 97 hp, EFI 105 hp.
RE: increasing torque without any big modifications
I got quite good at coaxing a fantastic picture from my last and best CRT display. I could go through all the settings to get that thing calibrated for a perfect picture on a good day, winding out drifts and compensating for environmental conditions. And regular degaussing. It was a shame to see it on the heap at the local recycle station, with all the others. My flat panel displays lose to the CRT in some areas, but they are overall better and more fit for purpose.
Steve
RE: increasing torque without any big modifications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
Port EFI's claim to fame - "I will always run the right AFR"
4 Barrel Carburetor's claim - "I will deliver more horsepower than EFI if we are both running the same AFR"
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
when you did your carburetor conversion what intake manifold did you use?
Did you have to spend any time equalizing cylinder-to-cylinder airflow?
Did you have to spend any time equalizing cylinder-to-cylinder AFR?
Do you happen to have the dyno tests of FI vs carburetor?
regards,
Dan T
RE: increasing torque without any big modifications
I did not spend any of my own time equalizing cylinder-to-cylinder airflow. I sometimes put a thermometer at various parts of the exhaust manifold just in case something extreme happens with the EGTs. I am trusting that the OEM intake manifold distributes air evenly enough that its not worth messing with.
Cylinder-to-cylinder AFR was not checked, because each cylinder bank is getting identical AFR at all times.
I recently moved (this week) but I will try to find those charts.
In the mean time: https://www.youtube.com/watch?v=_mYhKfSIRVQ
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
Cylinder-to-cylinder AFR was not checked, because each cylinder bank is getting identical AFR at all times.
Not very likely. Port fuel injection manifolds are designed for even air distribution with out regard for even fuel distribution. It is very difficult to get both even fuel and air distribution, something the old carb manifold designers had to deal with.
The problem with carbs is you can get good power, good fuel economy or good emissions. Choose one. The others will have to suffer. So in today's emissions controlled environment a carbureted engine (aren't many left other than lawn mowers) will suffer in both fuel economy and power.
And I seriously don't believe your claim of decreased power output when the switch was made from carbs to EFI in the 80's. As the emissions requirements increased the carb engine power outputs were dropping like a stone. It took EFI & the 3 way cat to save the automobile for some truly awful engines.
Just take the evolution from the last C3 Vette to the first port injected C4 Vette.
In 1981, there was only one powerplant available, a 350 cu in (5.7 L) carbureted engine that produced 190 hp.
1982 saw the debut of the “Cross-Fire Injection” TBI system, the engine produced 200 hp (continued in the first C4's).
The new 1985 L98 350 added tuned-port fuel injection, which was standard on all 1985–1991 Corvettes. It was rated at 230 bhp for 1985–1986, 240 bhp for 1987-1989.
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: increasing torque without any big modifications
Also, why did you choose a car with TBI to represent your cylinder-to-cylinder tuning concept? They also bumped the compression ratio up from 8.2 to 9. Thats a big difference when you are dealing with low numbers like that. In my opinion, TBI has more in common with a carburetor than it is to Port EFI. That is why I have specifically been referring to port efi to modern carburetors. I am only making the claim that there are things that a carburetor does that port EFI does not, and one of those things is having the most potential for peak horsepower. I'm not saying that EFI isn't great at everything else. If you have money and need to adapt your car to conditions in just 3 practice laps, then go with EFI.
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
While I agree that there were some very elegantly optimized carburetor setups back in the day, I don't subscribe to that generalization. For the simple reason that, a carburetor that is accurate from part to full load of necessity imposes an appreciable air flow restriction at WOT, in order to have a sufficiently accurate pressure drop vs flow to be used as a signal for fuel metering. Of course, some fuel injection air metering systems impose their own pressure drop (e.g. vane meter, MAF), but these can typically be of lower order than a state of the art accurate carburetor.
Furthermore, when considering PFI vs single point carburetor, air manifold design imposes its own restriction to airflow, in order to mitigate inherent maldistribution issues of air and fuel of a single point system. I hasten to add, PFI systems are not perfect, just inherently better than single point carburetors, in this regard.
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
Carburetors meter all of the air coming into the manifold. If there is air in the manifold, it theoretically already has the correct amount of fuel metered into it.
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
Regarding 1 carb/cyl., I agree, it works well (assuming proficient application & calibration), but is OT relative to your original claim regarding 4BBL carburetors.
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
The rotating mass of the crankshaft is dynamically balanced by the counterweights and produces very little mechanical losses at the main bearings. Most of the mechanical friction losses in a recip engine are due to the dynamic forces produced by the reciprocating conrod and piston masses, and the high sliding frictions at the ring and piston skirt contacts from high combustion gas pressures.
RE: increasing torque without any big modifications
The high-performance bike EFI systems usually use two injectors per cylinder nowadays - one near the port downstream of the throttle, and one in the airbox pointing straight down the intake runner.
RE: increasing torque without any big modifications
Carburetors meter all of the air coming into the manifold. If there is air in the manifold, it theoretically already has the correct amount of fuel metered into it."
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I think most sources would say the fuel provided by a carburetor is far from evenly distributed and thoroughly and uniformly mixed. Testing on the dyno may not simulate what acceleration does to the fuel in the carb, or the multi-phase mixture flowing into the engine.
https://www.youtube.com/watch?v=s-q1eJu1Wz8
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AMC Rambler's best effort to create equal AF ratio back in 1957 or so.
http://worldpowersystems.com/AMC/Rambler-327/The%2...
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" At this point, it hadn't yet become evident to dyno users that the use of in-car pieces (headers, ignition systems, cooling systems, etc.) on the test stand would be a logical step toward the need for linking engine testing with on-track performance. The importance of this fact was brought solidly home to me in the mid-'70s when sorting out some cylinder-to-cylinder mixture distribution fixes in a now bygone "Smokey Ram" intake manifold. Distribution fixes Smokey had determined on the dyno barely resembled what were required on the track."
Read more: http://www.hotrod.com/how-to/engine/ctrp-0808-powe...
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================
From the Hilborn INJECTION SITE -
http://www.hilborninjection.com/tech_elect_manifol...
"First it is important to keep in mind that the air and fuel have not mixed into a homogenous mixture in the venturi of the carburetor or in the runner of the intake manifold. A homogenous mixture is defined as a mixture whose physical properties are uniform throughout. Fuel in the manifold is not uniformly mixed as this only happens under the extreme heat and pressure contained in the combustion chamber. In reality, fuel in the intake tract uses air as a carrier; therefore, it is relatively easy for fuel to fall out of suspension, causing mixture distribution concerns."
And lots more.
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Here is a thread on a bulletin board showing some of the stunts that sometime have to be used to get carbs on "high performance" V8 manifolds to get the right amount of fuel to flow to the dry sections of the manifold.
http://racingfuelsystems.myfunforum.org/viewtopic....
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Post 10 here shows some of the carb assymetry applied by Chevrolet to improve the fuel distribution on the legendary L88 engine.
http://racingfuelsystems.myfunforum.org/viewtopic....
RE: increasing torque without any big modifications
Tbuelna - I wasn't really talking about friction as much I was talking about the actual rotating mass of the crankshaft and how it affects acceleration through the RPM range. Crankshafts have mass, which rotates. It takes torque to spin a mass in a circle. It takes more torque to spin that same mass in a circle if the mass is farther away from the center (higher moment of inertia).
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
The momentary hard acceleration you got from doing that, was the only hard acceleration you got ...
RE: increasing torque without any big modifications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
But on the other hand ... when the throttle is nearly open and the engine is spinning fast, fuel injected further upstream has more time to mix with the air and partially evaporate, cooling the intake charge. The throttle is open or nearly so when these injectors are in use, so there is no issue with the fuel droplets landing on the throttle blade and accumulating and then being fed to the engine in (relatively) huge drops, which is what would happen if you tried to use the upstream injectors at light engine load.
RE: increasing torque without any big modifications
Just read this thread so I may be a bit late, but just my observations.
I have a GMC motorhome, the one GMC designed and built back in the 70's using the Oldsmobile Tornado front wheel drive train. It came with a 455ci engine with a quadrajet carb. (www.gmcers.org)
When I bought it in 2008, the original card had been changed to an aftermarket Rochester 4 barrel carb. It had the usual carburetor issues (hard starting, hesitation, wont come off high idle, dieseling) all that good stuff. There is TBI kit for these machines from Howell EFI (www.howellefi.com), so I went with the EFI kit. It took me a bit to get all the bugs out of the system, but now it starts and runs like a modern engine.
I also added a more up to date engine control computer system (www.dynamicefi.com) and electronic spark control.
I had to learn about and deal with things like fuel condensing on the runner walls when the engine was cold, and clearing out the rich mixture from puddling (but that only happens from stone cold start-up in my case).
As far as torque and fuel mileage goes it does have more pep, although the electronic spark control seemed to make more difference there than the EFI. GMCer's say with a well tuned carb engine you will get 8 to 10mpg depending on whether you tow a car with you. I never had a good carb on it, but with highway lean cruise and deceleration fuel cut-off I have no problems getting over 10mpg even with my jackrabbit starts.
Just my experience
RE: increasing torque without any big modifications
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
So id concede this debate with a conclusion along the lines of: EFI is great at a broad field of applications (soccer moms driving vans to engine tuners tuning a car in real time). Carbs are great for shadetree mechanics and they have their place in some racing applications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
Steve
RE: increasing torque without any big modifications
www.tynevalleyplastics.co.uk
It's ok to soar like an eagle, but weasels don't get sucked into jet engines.
RE: increasing torque without any big modifications
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
Have you ever heard of a turbulent jet igniter? It does this VERY well. There are a few variations to it, but they all work in the same way. They ignite the fuel charge with the turbulent particles instead of directly exposing the charge to the spark.
You get a much more uniform and instant burn when using one. That means you can have the fuel/air charge release more of its energy when most optimal. The combustion will be more precisely concentrated, which allows you to get higher combustion pressure when you want it.
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin
RE: increasing torque without any big modifications
"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz
RE: increasing torque without any big modifications
???
RE: increasing torque without any big modifications
RE: increasing torque without any big modifications
Lean-burn might be an efficiency-improver in some circumstances but it is not a power/torque adder. The engine will make less torque in lean-burn mode than in stoich mode.
MAHLE is a large and reputable company, so something of this sort coming from them warrants paying more attention to it than if it were coming from the usual quacks.
RE: increasing torque without any big modifications
There are a few papers by William Attard who worked on this research with Harry Watson at Melbourne University before going to work for Mahle.
je suis charlie
RE: increasing torque without any big modifications
And there are various versions of turbulent jet igniters that could work in certain engines without changing the architecture. Spark plug angle is important here
"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin