You will need to run a smaller diameter rotor and relocate the caliper to fit a 15. You may also run into wheel-to-control-arm rubbing, depending on the backspace and steering angle.

 

This is actually a complex question. First, I'm assuming you mean lighter flywheel,not smaller. Secondly, no, torque will not change. A dyno plot will look the same regardless of flywheel.

However there is a little bit of an inertia effect, similar to lightweight wheels. With a heavier flywheel some of your acceleration energy gets stored in the flywheel as angular momentum as opposed to put to the ground. Then when you let off the gas that stored energy gets released and the effect you see is that the revs drop slower than if the flywheel had been lighter. So if you're accelerating, a heavier flywheel would slightly decrease the torque that gets to the wheels, but the effect is very small, negligible really.

On the other hand when you're launching it would be the opposite - a heavier flywheel would let you store more energy in the driveline prior to launching, that would then get released when you drop the clutch. So you'd then see a corresponding increase in torque as opposed to decrease.

I would just think of it as no, it doesn't change your torque.

If you actually did mean smaller, then the answer is still no, it doesn't affect torque.

 

But I guess the trade off is that while you can "dump" less energy at launch, you also have less mass to rotate so in theory shouldn't that help with acceleration?

 

Yes, like i said it does that but the effect is pretty negligible. You're talking taking away what, 8 lbs, at a pretty small radius? When you're accelerating 2800 lbs w/a driver and rotating hundreds of pounds of stuff like wheels and drivetrain components, that amount of inertia is tiny. When it matters a lot is when you press the clutch in and disconnect all that stuff to rev match, etc.

 

In that case I'll just resurface my AP1 fly. It's light enough. Thanks.

 

Steve, are you still running the 4.3 in the rear? I don't think that is BSP legal

 

My diff is getting pulled out of my car over the winter and being sent to s2kpuddydad so he can put back the stock FD and also the correct stock AP2 flange (since I have an AP2 housing) to make it legal. I also still need to get most of my interior back in the car. Haven't had time to do that yet.

Ironically isn't having 4.3s in an AP1 like having AP2 gearing anyway? So when I get my diff back but put in an AP2 diff I probably won't notice a difference.

 

You should get a lighter flywheel & sell me your AP1 FW.

 

I might actually do that. But I don't think I'll go lower than 11 lbs. I also really wish I didn't have to ditch my F20C. I feel really bad pulling out a perfectly good engine out of my car. Oh well.

 

Why not try the AP1 out for the first half of the season? It might be an advantage with the higher redline.