increasing torque without any big modifications 2

[Deividas]

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?

 

[140Airpower]

....how much ecu remap can reduce engine reliabilty,....?

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.

 

[Deividas]

number of power strokes/minute

What do you mean by saying power strokes? I'm asking, because in wikipedia: p(me)=(T*nc/Vd)*2pi, and wikipedia says, that nc is number of revolutions per power stroke (for a 4-stroke engine nc=2)(

http://en.wikipedia.org/wiki/Mean_effective_pressure).

So, if power stroke is one of 4 strokes (intake, compression, power, exhaust), how can be 2 revolutions per power stroke, if power stroke is only 180deg crankshaft rotation? Maybe i'm missing something?

 

[Deividas]

And also says: "When quoted as an indicated mean effective pressure or IMEP (defined below), it may be thought of as the average pressure acting on a piston during a power stroke of its cycle" and then says: "Indicated mean effective pressure (IMEP) - Mean effective pressure calculated from in cylinder pressure, average in cylinder pressure over engine cycle (720° in a 4 stroke, 360° in a 2 stroke)"

 

[gruntguru]

"Two revolutions per power stroke" is describing the frequencyof the power strokes ie on power stroke per two revolutions - not the duration.

je suis charlie

 

[dicer]

Force more air into it.

 

[1gibson]

Take it to a lower elevation.

 

[Panther140]

Changing your timing and getting rid of parasitics would be the only real options you have left after you take out things that use more fuel. Bigger cams, forced induction, lower intake charge temps, and lower elevation all increase volumetric efficiency which requires more fuel and more air.

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

 

[Panther140]

Timing has a massive effect on engine power. Changing 2 degrees of timing can yeild 5-7% power gains. Manufacturers set up their engines with some room for error in fuels, failure effects, and adverse conditions. They dyno test engines on E-10 fuel which is always the same. That fuel in the pump down at the kum & go truck stop isn't quite as consistent, so they have the timing retarded enough to compensate for detonation that might come from running crappy fuel and climbing the rocky mountains while towing at 100% capacity in 120 degree heat. You can tune your own ignition for your specific intents and purposes and get noticeable gains in power depending on how the stock ignition map was set up. Some modern cars are doing an excellent job of it, other cars need about 4 degrees of timing added at some points.

"Formal education is a weapon, whose effect depends on who holds it in his hands and at whom it is aimed." ~ Joseph Stalin

 

[Panther140]

"5.0 V8 which i mentioned before, how much torque (or bmep) increasment i can expect, if i change carburetor to multi-point injection with ecu controlled ignition, (or if it already has ecu, if i remap it) and other inlet and exhaust headers, but not increasing my fuel consumption?"

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

 

[Deividas]

Panther140 - Thank You for answers

 

[gruntguru]

"You will lose power if you go to port EFI"
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

 

[Lou Scannon]

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.

That's an interesting statement. Can you please give the physical basis for it?

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[BrianPetersen]

"Every car lost power when they switched to port injection EFI in the 80s"

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.

 

[SomptingGuy]

Carburettor obsolescence. A real shame for those who love the inspired and beautiful engineering. But the contraption really is obsolete now. Simply not up to the job required - mass-market closed-loop transient AFR control. On the same scrap heap as the equally brilliant distributor diesel fuel pumps that were far more exciting and clever than the engines they were connected to.

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

 

[Panther140]

hemi - a V8 Crankshaft weighs 50-80 lbs, usually has a pretty big radius, and spins 5,500 RPM. One thing we do to test engine parasitics on an electric dyno is to spin the engine over by using the electric dyno and measuring how much power it actually took to spin the engine. This huge moment of inertia in crossplane counterweighted V8s is one reason flat plane cranks are preferred for a lot of 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

 

[Panther140]

gruntguru- They are using port EFI because it can be adjusted real time. That is the advantage of it. It is always running right.

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

 

[Tmoose]

Hi Panther,

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

 

[Panther140]

Tmoose - I used the stock EFI intake manifold. Everything on the car was bone stock except for the carburetor and ignition module at the time. I just made an adapter to bolt onto the intake manifold that would allow me to bolt a 4 barrel carburetor to it.

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

 

[dgallup]

Panther140 Quote:
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.


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

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.

 

[Panther140]

Be sure you're comparing apples to apples here. That crossfire 350 does not represent the Port EFI that I am comparing modern carburetors to. Nor does it represent a controlled experiment as it has 10% higher compression than the 1981 car. The 1985 mustang GT made 210 horsepower with a 5.0 and a carburetor. The 1986 Mustang 5.0 made 200 horsepower with EFI and higher compression in the same engine.

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