Basically this mimics a clutch on the engine dyno. Saw this and thought people would like to see it
http://www.superchevy.com/how-to/eng...eel-why-weight

 

I love 11lb aluminum flywheels and RXT clutch combos! lightweight flywheel is sooo much more fun to drive. Engine also rev's up waaaaaay faster.

 

Article would have carried much more weight if it had considered typical real world acceleration rates rather than a typical dyno test acceleration rate. I did a series of tests a while back on a couple of otherwise identical sbc engines. One had a 49lb stock crank, heavy 8" balancer, and 1863g bobweight rotating assy, the other a 42lb pendelum style crank, liteweight 6" balancer, 1492g bobweight. Same clutch/flywheel/compression/cam/carb. Basic difference was one had stock crank and steel I beams, the other had sprint car crank with aluminum rods. The 1st gear accel rates of 1975/2217 rpm/sec worked out to a 276ftlb difference between the two, by 3rd gear the accel rates of 535/541 rpm/sec it was only a 6ftlb difference. Wonder what the accel rate was during the article's dyno test?

Grant

 

Not a GM product but when doing the clutch job I replaced the flywheel in my S197 mustang with a lighter unit from ACT, 8 pounds lighter, and its quite noticeable. Ford should have built the car with this clutch and flywheel, the car even starts better.

 

Engine Masters show Season 5 episode 72 did a test with weight. Been a while since I saw it but from what I remember the standard dyno acceleration rate of 300rpm/sec didnt show much of a change, but at 600rpm/second it showed decent gains. Which makes sense, trying to accelerate a heavier flywheel fast is going to take more power.