The aluminum flywheel will help you decelerate quicker and accelerate a tick quicker if you want that little extra addition but some things to think about with the AFW is starting from a stop, particularly on hills, may require more slipping of the clutch to make up for the lower momentum than is stored in the heavier stock flywheel. Some jerking can be occured due to the loss of momentum possibly in between shifts for example as the rpm will drop sooner.
I would stay away from an aluminum flywheel on a daily driver and plus some of the harder grabbing clutches can tear up the aluminum flywheels...and aren't recommended with a aluminum flywheel.
Get a stock replacement or a nice billet steel one...(more expensive)...
This is posted from FastDriver - The answer to your question is that a 15 lbs weight would be easier to catch/stop if it has been thrown at you at the same speed as a 40 lb weight. A pretty obvious answer, but I think you are misinterpretting the results. A drag racing launch has nothing to do with ease of launch. If it did, you wouldn't launch at 6500 rpm, you'd launch right off of idle. Also, my clutch doesn't seem to have any problems grabbing my flywheel at any rpm. My tranny doesn't seem to have any problem managing the shock, and with the right tires and
suspension, I will launch this car right off of redline with a single clutch drop.
The point is that you want as much stored energy to jump into your tires as possible, and you want your
suspension/weight distribution/ tire combination set up so that it can handle all of the power and effectively put it to the ground - as opposed to wasting it by blowing away the tires.
In regard to your posit about stored energy being meaningless, I'll counter that stored evergy has everything to do with the difference between a heavy flywheel and a light one. In fact, stored energy is the only cause of a performance difference between an aluminum and iron flywheel.
The aluminum flywheel does not store as much energy as rpms increase which gives it an advantage in that the energy that would be stored in the flywheel has instead been exerted into the rotational force in the drivetrain and hence the driving force/power of your car.
In drag racing, that extra stored energy in the flywheel at a stop is put into your tires as soon as the clutch is dropped causing more force/power driving your car as it leaves the line. As your car moves down the track and rpms increase, the energy is transferred back and forth from the flywheel to the tires as rpms increase and then decrease (as you shift). Finally, when you cross the traps, rpms at the top of their powerband, the stored energy in the flywheel did not get put to good use. So, the advantage after you leave the line is to the lighter aluminum flywheel. Does it make up for the Iron one? Possibly. The longer the track, the more likely. However, will the difference be significant enough to justify the extra expenditure? Not to me.
Good Luck with your choice.
