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MG MGB GT V8 Factory Originals Technical - Smaller Pulley?

I was watching a car show yesterday and the guys exchanged the stock pulleys for smaller ones, claiming it would increase hp.

Anybody tried this? Does it work? What are advantages/disadvantages? I have a early 215 in my gt.

David
David Atherton

Sounds like a supercharger. Smaller pulley = higher rpm's = more boost = more hp.
Justin

David,

A smaller crankshaft pulley will free up hp that is otherwise tasked to run the water pump and alternator. Think about how the timing chain works with the smaller crank sprocket has half the teeth as the cam sprocket and therefore the crank will turn twice for the cam to turn once. Now back to the pulleys; the larger the crank pulley the faster the water pump and alternator will turn. Im sure you can understand how turning the water pump faster requires more hp so turning it slower frees up hp. The disadvantage is that coolant is moved slower and may be insufficient to keep the vehicle from over heating and the alternator may not produce enough current to keep the battery charged particularly with the headlights on. This is good for drag racing where battery discharge and overheating is not a problem over the time it takes to go a quarter mile.
George Champion

David,

A smaller crankshaft pulley will free up hp that is otherwise tasked to run the water pump and alternator. Think about how the timing chain works with the smaller crank sprocket has half the teeth as the cam sprocket and therefore the crank will turn twice for the cam to turn once. Now back to the pulleys; the larger the crank pulley the faster the water pump and alternator will turn. Iím sure you can understand how turning the water pump faster requires more hp so turning it slower frees up hp. The disadvantage is that coolant is moved slower and may be insufficient to keep the vehicle from over heating and the alternator may not produce enough current to keep the battery charged particularly with the headlights on. This is good for drag racing where battery discharge and overheating is not a problem over the time it takes to go a quarter mile.
George Champion

This thread was discussed on 05/01/2004

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