Any advantages or disadvantages .I saw someone caliming a gain of 5 -25 hp .True ??or sales B.S??
TX
MIKE

 

True sort of. The pulley ratios make it easier to turn accesories so the engine doesn't use as much power. You don't really gain engine HP, you just don' use as much. I have noticed on A/C cars the pulleys are differnt sizes than non A/C. Underdrive from the factory.

 

Gear reduction. At a given RPM the underdrive pulleys will spin your accesories at a lower RPM than with your originals putting less load on crank pulleys. Down side is you can loose some juice that you are generating from the Alt., your water pump is going to spin slower, pushing less water and the ebay pulleys are generally cheap aluminum that can easily get eaten up by belts.

I have never tried them on an olds but have used alum. underdrive pulleys on an FD3 RX-7 and alum overdrive blower pulley on a T-bird Supercoupe. Both were bad news. RX-7 pulleys got eaten up by belt (engine spun 9k RPM- should have expected this) and the T-bird pulley got eaten up as well.. but not before the additional speed trashed the blower snout.

Now I just leave them as they were meant to be used and they work fine.

 

25 HP is BS. 5 HP is pushing it.

 

tx all for the input.It shall remain original.
mike