Back in the old blown gas dragster days we used aluminum flywheels and direct drive. We didn't have quite enough hp to pull the way the Top fuel guys did so thus the alum fw. This is why we ran 8.0's and 180+ lots of top end. With the advent of the slipper clutch we tried the alum fw but there was too much heat and many found the hard way what happens when a clutch lets go at 8000+. We did...boom 2 piece race car.
Eventually the Crowerglide came along. It was alumin at first but it didn't hold up. We used a steel fw about 10# or so. They are much smaller than stock dia. but with 3 discs and floater they probably got up to 30 pounds or better. I remember them being a handfull to pack a complete one around.

I remember some of the old gassers using 265 and 283 that used 50-60 fw. they would wind them up to 8500 and dump the clutch. The motor stayed there while everything else caught up....if it stayed together. I saw one 2 piece 55 chev that was a tremedous blast. parts flew everywhere.

bentwings