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Author Topic:   Lightweight Rotating Assembly
posted October 07, 2004 10:04 AM
When does a light weight crank, rods etc start to show its benifets?

What i mean is for 1200 to 1500 bucks will that light weight crank make more power in a 500 hp motor? is it worth it in a motor that only makes 500 hp to begin with?

I know the lighter stuff will make more power but my question is it worth it? It would seem that reliability would go down hill as well.

Seems to me for motors making under 700hp the light weight stuff has no use. Better off going for nice reliable parts (name brand 4340 stuff, american), and spending more money on good heads, cam etc. Or is my thinking wrong here?

posted October 07, 2004 10:18 AM
Lightweight stuff wont necessarily make more power but it will spin up and slow down quicker. You will notice this coming out of the corner it will rev quicker making it feel like it has more power, and when you lift you will notice the car braking quicker because the engine has less inertia and will slow the car down faster.

Same goes with light pistons and rods. It is that much less mass that has to speed up and slow down. and lighter rods and pistons will put less stress on the cranks and bearings evertime they change directions.

I would say lightweight stuff is very much worth it to a point. It does get pricey so you have to weigh that in your options. Also you can go too light and lose durability. What may work for a 450HP 2 barrel motor prob wont hold up in a 600 HP 4 barrel for instance.

posted October 18, 2004 06:42 PM
Bang for the buck, going to a 6" I beam rod is the single biggest gain you can do. That forces a shorter, lighter piston. Going to a 6.2" rod is even lighter. The weight of the piston is the biggest factor then the weight of the crank, balancer, flywheel etc. Even a 'stock' weight piston for a 6" rod will be about 50 grams lighter. That's HUGE.

Any motor that spins will benefit from a lighter assembly.