[hbanger]

What is better a light flywheel or a heavy flywheel? Is there a performance or drivability difference?

 

[rodent]

Depends, yes, yes

 

[Pragmatist]

Where to begin.....What car are we talking about and how will it be driven?

 

[Mike Goble]

The actual effect of a lightened flywheel:

http://www.uucmotorwerks.com/flywheel/how_a_lightweight_flywheel_works.htm

I used a 9# Fidanza flywheel on the 490 hp 331" motor for the Durango Deuce and it made quite a difference. No driveability problems at all, if you have your engine set up right you should be able to just let the clutch out and go. Another benefit is enhanced cornering ability due to the reduced gyroscopic effect.

 

[Alf]

As several have said, "it depends".
What I would caution you of who makes it and where. There are Chinese billet light flywheels that are sold as SFI certified. When you get them there is no SFI label attached. If there is no label then it then it is not SFI.

Personally, I'd not have a flywheel that is not SFI certified.
Unfortunately, a good American certified flywheel is 3X as expensive.

 

[Twinshadows]

hbanger

Brian , When I did my T 5 install , I bought a 'replacement Flywheer from Summit. 'Perfection Replacement Flywheel' # 50 - 6516 , for 10.5 clutch., and 153 tooth. It's most likely a China unit ... but, working great & smooth ....
just FYI

have fun ... jim

 

[hbanger]

Story about the vague question. I was just wondering what the difference was between a light VS heavy flywheel, not for any particular application but in general

 

[hbanger]

hbanger

Brian , When I did my T 5 install , I bought a 'replacement Flywheer from Summit. 'Perfection Replacement Flywheel' # 50 - 6516 , for 10.5 clutch., and 153 tooth. It's most likely a China unit ... but, working great & smooth ....
just FYI

have fun ... jim

The one in my car is a lighter than stock replacement from one of the local auto part stores. So far it seems to be working just fine.

 

[Mike Goble]

Story about the vague question. I was just wondering what the difference was between a light VS heavy flywheel, not for any particular application but in general

Generally speaking, anytime the clutch is fully engaged a lightweight flywheel is better. Less rotating mass is good for acceleration.

 

[Rick_L]

Let's see if I can take this a little farther.

Mike G. said lighter is better once the clutch is fully engaged and that's very true. A light flywheel is less rotating inertia which has the same effect as a lighter car weight. A sprint car with no transmission uses the lightest flywheel possible for that reason.

But a heavy flywheel can help with acceleration of a heavy car, especially with a small engine. If you dump the clutch with a light flywheel and you have traction, rpms will drop. A heavy flywheel won't let the rpm drop as much - so the engine won't bog down. Back when NHRA had the Modified classes, the F/MP and G/MP as well as the H/G cars had 283 or smaller engines and weighed over 3500 pounds. The typical combination had a 50 or 60 pound flywheel.

Likewise on a small engine/heavy car you can get less rpm drop on a gear shift with a heavy flywheel.

All this is a back and forth deal on launching and shifting vs. acceleration in a particular gear, vs. car weight and traction. Shift points and gear ratios play a big role here too.

In the end, with a lot of combinations including many stock ones, a 25-30 pound flywheel is the best compromise. That's why stock flywheels are 25-30 pounds. And much of that takes into account part throttle everyday operation as well as performance.