just had a quick question about underdrive pulleys, do they really make the 15 horsepower that they claim? i just dyno'ed 284/327 and would like to have 300 hp. also, is there any specific brand that anyone would recommend.

 

I'd say 3hp is more likely, but what do I know I don't even have them. It just seems if they were that efficient they would have made them OEM.

- Z28WannaB

 

I agree, you won't see anything really with them. Mostly they will reduce the amount of drag on the engine accessories. And possibly help with your electrical system. I wouldn't recommend them. Just my .02

 

I have them and dont see any gain also Id had a problem with alt. pulley being to small so I only use the crank pulley.

 

15HP might be remotely possible on an engine with a belt driven water pump and a belt driven AIR pump..... your LT1 has neither.

http://www.ws6.com/mod-2.htm