Blowproof Bellhousing & Aluminum Flywheel?

[patrickt]

Originally Posted by Ron61

... you also lose some of the deceleration when you get off the gas and have to use the brakes more.

Ron, are you sure about this? I would think that the stored energy in a higher weight flywheel would require additional braking to slow down. Surely there's a mechanical engineer on here that could answer the simple question: "If a Cobra is travelling, say 120mph at 5000rpm, does it take more brake force to bring it to a stand still if the flywheel weighs 18lbs or if it weighs 25lbs?" No fair pushing the clutch in during braking.

[Buzz]

Originally Posted by patrickt

Ron, are you sure about this? I would think that the stored energy in a higher weight flywheel would require additional braking to slow down. Surely there's a mechanical engineer on here that could answer the simple question: "If a Cobra is travelling, say 120mph at 5000rpm, does it take more brake force to bring it to a stand still if the flywheel weighs 18lbs or if it weighs 25lbs?" No fair pushing the clutch in during braking.

I have to go with Paddy on this one. A heavier flywheel retains more inertia and resists changes in engine speed far more than a lighter one, whether accelerating or decelerating. Lift off the gas at high rpm and the heavier flywheel acts like a gyro and just wants to keep on going. The lighter one is far more responsive on deceleration as it offers less resistance to changes in engine speed (ie: "engine braking").

[Ron61]

Buzz,

I am no engineer and am not trying to BS anyone, just going on my own experience and that of my friends. I do know we drove each others cars quite often and I could tell the difference in how fast mine slowed down compared to his. Maybe it wasn't the flywheel, but except for that we had identical engines right down to the stroke and power. I know his did wind up a little faster but I didn't think it was enough to justify the extra expense for a street car. And I had no problems at all when racing in keeping up with or passing him. I could drive deeper into the corners as he started braking about a car length before I touched mine. Truthfully I had always thought that the steel would be slower to stop also. Maybe there was something else about his car that was causing this. We had the same compression, but I had to watch mine to keep from hopping the rear wheels while I could downshift his at the same RPM and it didn't do it. I am not trying to convince anyone that one or the other is better. I just answered the question from my own experience.

Ron