iloveporsches

No. Torque comes the combustion, and the subsequent mechanical linkage to the crank shaft. Its not going to suddenly be able to produce any more torque because you threw more mass on it.

streckfu's

If you put a lighter flywheel on your car, less TQ, and as a result, less Hp will be lost allowing the work to be applied to the rest of the drive train. Heavy flywheel=more drivetrain loss=LESS TQ and HP.

RMills944

You're looking at the equation wrong...

The engine does not produce more torque by adding more flywheel weight!
The flywheel requires more torque to move it! You are therefore producing the same torque at the engine, but less makes it to the wheels since the flywheel sucks up more of it to get moving.

Moook

OK girls
Bikering over ,,, this realy doesnt help my choice now does it.......??????????????

What i need to know ..
Is the car going to be better with a lightweight fly or worse.????

IE is it going to be quicker ??? as the weight is reduced...+ more power from the engine will be transfered to the wheels....
OR
will it be harder to drive..... ie more clutch judder or noise.??? + will i need to keep the engine "reving" to stop it stalling out.????

Ta
Dave W.

ideola

So what do you mean by quicker??? I may not have the science right, but I think my original answer still applies. IT ALL DEPENDS.

<big disclaimer>As I understand it</big disclaimer>, your car will have better overall acceleration with a lightweight flywheel, but will be slower off the line, which is what I've been trying to say all along.

To quote another knowledgeable member from another respected forum (which I cross-posted earlier):
"more flywheel weight = more torque. The flywheel in motion is stored energy - once it's spinning, it's gonna want to keep spinning and the heavier it is, the more energy it would take to make it stop. Horsepower is consumed in getting the flywheel up to speed, and that's horsepower that's diverted from contributing immediately to the cars' accelleration, but that energy used, becomes stored energy, stored as flywheel inertia and available as torque. A heavier flywheel also makes the engine run smoother...Anyone wanting horsepower and accelleration more than torque would still go for a lightened flywheel. That should be a racecar owner/builder though. It doesn't make much sense for a street car in my opinion where you'd want a smoother running engine plus more torque for the repeated stop-'n-go's"

RMills944

The car will revv up a little quicker with a flywheel since the engine has less mass to move.

Yes, it will make the car quicker. I will say that I rode behind a guy that had a lightened flywheel, and he didn't pull away noticeably. If you're in there to do the clutch, you can do it, but you also will have a problem with the car stalling if you go too light.

Mike S

I have the stock flywheel lightened on mine and all it does is make it rev slightly quicker in neutral. The revs also drop slightly quicker in between shifts. It's easier to stall at a light as well since there's less inertia. Any HP or torque benefits are bogus.

streckfu's

Also note, even though the reduced fly wheel weight will allow the engine to rev faster, the rpms will also drop faster making shifting and stop lights more interesting.

special tool

Okay - I won't add any more torque/hp bull**** - just experience.


My car has a Fidanza 6 pound flywheel, KEP aluminum 700 FT/ pound PP and solid hub ceramic 6-puc disk. I run it at 500+ HP on the street.
18 pounds all together have been removed from rotating mass.
It is a pain in the *** now, slightly to get going.
When it was only the lighter flywheel, it wasn't that bad at all - a good street mod, in my humble opinion.

Moook

OK folks
Update time...

As my car is a 91 944S2 , apparently "NOBODY" makes a light alloy fly for the S2.....
Ive been in touch with a number of US + UK performance suppliers + they all say NO not available.....
So that kinda stumps me .....
Back to the drawing board....

Dave W.

Geo

I hope so since you need to repeat it.

A flywheel does not add nor use torque or horsepower.

OK folks, a little remedial physics here.

The flywheel has inertia. It has zero effecto on torque or horsepower. I low mass flywheel will allow the engine to rev quicker, leading to quicker acceleration of the car itself, or an inertial dyno roller.

Let's talk about dynos.

Put an engine on a brake dyno with a 100 lb flywheel and measure the torque (from which you calculate horsepower, or pferdstarke or kilowatts if you wish). Now put the same engine on the same brake dyno with a 1 lb flywheel and measure the torque and calculate the horsepower. There will be no change in torque (and thus horsepower). This is because a brake dyno works by holding an engine at a given rpm. The more effort needed to hold that rpm, the greater the torque (and thus hp).

Now, put the same engine in a car with a 100 lb flywheel and dyno it. Change flywheels to the 1 lb flywheel and redyno. Now the dyno will show you just gained a buttload of hp. But this is false hp.

Why?

It's the difference in methodology in the dynos. There is no acceleration involved in measuring torque (and thus hp) with a brake dyno. An inertial dyno however works by rotating a drum of know inertia (acceleration). The faster the drum rotates, the greater the horsepower. Or is there more hp? If you lower the mass (and thus inertia) of a flywheel, the dyno results will show you gained hp. But this is incorrect. What you have done is changed the rotational inertia of all the rotating items. It is possible to actually recalculate the measurements to take into account the changed inertia of the flywheel and then the results would accurately show no gain in hp.

Reader's Digest version: Flywheels neither produce nor consume torque or horsepower.