Timmay!!!

Is one type clearly better than the other, or is there a trade off between the two? I imagine the alum will allow the motor to rev faster but will I have to rev the motor more to get rolling from a stop? Whichonebetter for a 90% street car?

PROMETHEUS PRIME

What the less weight does is remove parastetic drag. Much like what pullies will do.

Timmay!!!

I understand less parasitic drag=quicker revs but will I have to rev to 2k to get rollingas a result of less inertia? I don't have pullies so I can't exactly relate the two but guess I can imagine.

vsop

Go with the aluminum. Unless you have a need to keep the revs up between shifts like with a turbo the Aluminum will be what you want. You have plenty of TQ down low that the Aluminum will only make the car faster and will not hurt at all..

CrazyAl

+1

This motor makes a lot of solid torque down low. Stalling out at low RPM is not a concern.

Timmay!!!

Thanks for the replys fellas. Wasn't sure how a lightweight flywheel was going to affect daily drivability.

steelcomp

I'm going to have to disagree here, based on an assumption that you're interested in good off the line performance. Street racing, light to light, 1/4 mi., etc. Better to stick with a heavier flywheel. For road racing, quick acceleration and deceleration, lightweight is definately better.

Also, by going lightweight, you're notremoving parasitic drag, you're reducing rotating mass...there's a big difference.

When you have the engine revving at a dead stop, waiting to launch, and you suddenly introduce all that load, the engine wants to stop rotating. Simple physics. The inertia of the heavier flywheel helps the engine maintain that rpm and get things moving. Once under way, it has little effect on acceleration. In a road race application, you're typically already moving, and not trying to overcome that initial load. There, your concern is acceleration, and deceleration as well. A heavy flywheel on a road course will not let the engine decelerate as fast, making breaking more difficult. Accelerating out of a corner and through the gears is also more difficult with a heavy flywheelbecause of more rotating mass. That's why you seldom see 7" triple disc clutches on drag cars. Something like a big block that makes big low end torque can get away with an alum. flywheel at the drags and on the street, but I think you'll be disappointed.

Timmay!!!

See, thats what I was thinking. I wonder if most other people have thought about it this way or if they just go with the lightweight aluminumflywheels just cause thats what everyone else is doing. I'm leaning toward aluminum since Ido favor goodroll-on acceleration and nice mid-range to top end performance,but in drag racing when its apples to apples (or at least close) a good launch is the key to victory.

CrazyAl

Good post steelcomp.

However, in a drag situation a heavy (steel) flywheel can be both good and bad.

As you stated, the extra interia of the steel flywheel can be benefical when you're at the line. If you have the engine revved and you drop the clutch, you havestored-up energy in that flywheel that you can then use in those first few tenths down the strip. HOWEVER, from that point on, the extra inertia of the flywheel becomes a hindrance, just like on a road course. Once you have gotten moving and your RPMs start to climb, that flywheel is now a hindrance. After the 20' mark the heavier flywheel is costing you power.

To determine if the steel flywheel would be a better choice, you'd have to compare wether or not the benefit at the line outweighed the power loss due to extra inertia once you're moving down the strip. I don't know the answer to that question, and it would depend on the specifics of the car, the engine, and so on.

Now then, I am not a drag racing expert. I hit the strip but there are other guys here and elsewhere who have many, many more passes than I. But in my experience, the lightweight flywheel has reduced my 1/4 times slightly, and the "butt dyno" certainly reports strong acceleration through the gears.

Norse1974

LOL! "Butt Dyno" Hahahahahahahaha!That was funny to me for some reason!LOL!