HP vs Crank Weight?

[carguy07]

Saw this on another site.

"How do Unorthodox Racing pulleys give me more power?"

Weight reduction is how we are able to increase Horsepower! Each pound of weight removed from the crankshaft is worth approximately 2.7HP and the gains jump even more dramatically with forced induction, nitrous, VTEC and increased RPM's. Only 15-20% of the gains from our pulleys come from underdriving.

Does this make sense to you? So a lightweight flywheel or pulleys will make more HP? Of course it spools up quicker, but HP?

[Mark Hahn]

That is true although 2.7 HP seems a little high for each pound. One of the problems with the lighter pulleys are that the Harmonic balancers on the front of the crank are reduce just that, harmonic vibrations. By lightening the pulley's without rebalancing the crank can instill more harmonic vibrations, especially at higher RPM's that can be destructive to engines. I would leave the crank pulley alone and lighten the other pulleys. Do a search on the internet about lightened pulleys and harmonic vibrations and I imagine you could find technical bullentins on the subject. For short term HP it is a easy way to go but not the correct way although places like Unorthodox racing have made a lot of money selling these lightened pulleys. MGH

[carguy07]

I guess it's the 2.7HP/LBs thing that seems like BS. That would make an aluminum flywheel worth over 40HP.

[Jack B]

If anyone wants to read a fantastic article, this months Hotrod magazine went into depth on the relationship of reciprocating mass and hp. They actually tested (dyno and track) two cars with multiple set-ups. They covered wheels/tires, driveshafts, flywheels and harmonic balancers.

[Go Fast For Life]

If each pound is worth 2.7HP, why not just remove the 70 lb crank??? That ought to be worth about 180HP!!!