overdrive balancer
Thread Starter
Burning Brakes
Joined: Nov 2000
Posts: 1,123
Likes: 145
overdrive balancer
Did a brief search and didn't see this question asked or answered, so here goes:
What does an overdrive balancer do and why wouldn't you want to underdrive the power steering, a/c and other useless stuff? The water pump you wouldn't want to underdrive, but all the other junk?
Explain to me, please.
What does an overdrive balancer do and why wouldn't you want to underdrive the power steering, a/c and other useless stuff? The water pump you wouldn't want to underdrive, but all the other junk?
Explain to me, please.
Race Director
Joined: Sep 1999
Posts: 12,438
Likes: 919
From: CONCORD NC
I've never seen an overdrive pulley. We underdrive everything for track cars...the sustained high RPM makes up for the lower ratio compared to street usage. Small aluminum damper and smaller 5" clutch shown
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
About the only reason you'd want an overdriven crank pulley is to spin a blower faster. I'd opt for an underdriven crank pulley to spin all of the accessories slower to save a few HP on anything naturally aspirated. Usually, you up the idle speed a bit when you add a bigger cam. If you do that, you won't overheat or undercharge at idle. Once you get above idle speed, it's a moot point. Not much downside to an underdriven crank pulley if you're naturally aspirated.
Le Mans Master
Joined: Dec 2005
Posts: 6,999
Likes: 1,685
From: Southeast TX
There are three types of crank pulleys. Stock diameter available OEM or aftermarket. Overdriven (larger diameter) available from the aftermarket. Underdriven (smaller diameter) available from the aftermarket. Folks with belt driven superchargers are about the only ones running the overdriven crank pullies. Those with exhaust driven superchargers (turbos) and those naturally aspirated can benefit from an underdriven crank pulley.
