I recall UL (remember him?) saying that a lightened flywheel on our cars would make a noticeable difference on his dyno -- on the order of a few peak hp at the hubs.

Also note that Formula's, uh, formulas, are expressing inertia, not torque, so the units are quite different. His 0.375lb-ft^2 is properly interpreted as 0.375 (lb-mass)*ft*ft, whereas a unit of torque is the (lb-force)*ft.

Regardless, this should all be pretty easily testable on a dyno.

 

Yes, my error there. I was using lbs as a mass instead of a force, I should have been more specific since lbs is usually a force. In this case it was irrelevent since I was looking only at ratios, those lbs could easily be converted into kg. So you described the units corretly as mass * distance * distance.

cthree, sorry for the confusion. I did not think a flywheel would make a noticable difference in acceleration until I did the numbers myself (you did say prove it ), so I had to revise my opinion. I used second gear as an example because it's the lowest gear I've gone down to on my local track, maybe mosport is faster. The effect diminsihes at higher gears and as aerodynamic drag overcomes inertial acceleration, but it is still there.

I know you did not say lightweight wheels affect acceleration, but I am saying it. The numbers tell me a flywheel could have similiar affects, if only in the lower gears. Obviously, in the racing context, it's still better to get lightweight wheels for the unsprung mass savings and increased deceleration.

Again, it's important to note that a dyno that measures steady state power will not be affected by the flywheel. The time a pull to redline takes will decrease, however. Also, an inertial dyno should actually reflect the gains. As in this article.