flywheels

[azgearhed]

I'm looking for credible information on the differences between heavy vs light flywheels as it applies to LSR in high HP heavy cars.

[SPARKY]

requires less ballast 

[kustombrad]

Split the difference!

[Milwaukee Midget]

I've seen the debate flop both ways, advertisements and arguments in favor of lighter flywheels claiming faster acceleration rates, heavy flywheels "robbing power", etc.

I think this is the issue at hand.

You're flat out for 5 miles.  What is critical is a balanced bottom end, and that includes the flywheel.  I'd suggest using the best quality SCTA compliant flywheel you can afford which will require the least amount of machining to bring the final assembly into balance.

[manta22]

The flywheel's weight is most important in drag racing, where acceleration is paramount. A light flywheel requires less engine torque to quickly spin it up to high rpm, so in a light car it helps lower your ET. Conversely, in a heavy car a heavy flywheel helps launch the car off the line by storing energy and dumping that energy into accelerating the car off the line when you pop the clutch. The heavy flywheel is spun up to high RPM at the line just before the 'tree starts counting down. In a heavy car there is less loss of acceleration due to spin it up again under power that it would be in a light car.

In LSR there is plenty of time to spin up the RPM so the question of a light/heavy flywheel isn't too important.

Regards, Neil  Tucson, AZ

[azgearhed]

I've been running a steel flywheel with a dual disc clutch that has worked ok for the last 3 years, but now we are driving through that clutch. The clutch we are considering, a 2,000 hp unit, is packaged with an aluminum flywheel. I'm trying to consider everything that the switch to aluminum will affect. I'm thinking that decreasing the throttle pedal ratio might be necessary since the engine will rev quicker with the lighter flywheel, maybe making tire spin harder to control....might be over thinking it?

[John Burk]

For a car geared to go 250 mph the center of mass of the flywheel goes about the same speed as the car . A 7 lb difference in the flywheel is the same as that much difference in the weight of the car .  Too small to measure .

[Dynoroom]

This dual disk clutch with aluminum flywheel was used on a 1050 lb/ft 5200 lb 300 mph car.... I don't think it matters which flywheel you run at Bonneville. I still run a small light clutch at El Mirage, again I see no issue.

The small clutch assy is good for 1000 hp but only about 350 lb/ft of torque.

Torque capacity is what a clutch should be rated by IMO.

[azgearhed]

We never had a clutch problem at Bville, only at Elmo this year. According to the clutch people, the clutch we have been using (double disc) is a street clutch that was not intended for what we were doing with it. In our case, ignorance worked out ok at Bville as the car made it to impound 4 times in 2 years.

[Interested Observer]

A more extensive discussion at "Aluminum Flywheels"

http://www.landracing.com/forum/index.php/topic,13328.0.html

[kiwi belly tank]

It appears that all your engines are over 500" so a light flywheel might contribute to wheel spin getting on the throttle & possibly even some rear wheel lock up getting off the throttle. Both of these conditions are undesirable in our world & anything you can do to help prevent this is worth while.
Some people will say "I just ease out of the throttle" but if that short rear wheel drive bitch steps out, you aint easing out of the throttle.
I have an auto trans with no converter & the heaviest flywheel I could find.
 Sid.