Quote Originally Posted by SammyPain
the pully is bigger than the original or smaller i forgot...its like having your accesories all run on a shorter gear. like you know how its easier to accelarate in 1st gear rather than 2nd. its a gearing thing. some of them are lighter in weight than the original so they have less unsprung weight but thats not whats responsible for freeing up the hp n torque its the size of the pully that does it.
I see...but I just don't see how a smaller/larger would free up power if the weight of the pulley (due to its size) is changed.

The only way I could see that making a difference is rotational-weight; such as the same purpose of getting a lightweight flywheel. And on a 4banger, I don't see how that LITTLE amount of change in weight could cause the advertised power gains (granted, we know with advertising, they like to bump the real readings). However, on a v8 (like my latest car) I would think that as much weight as extra four cylinders has, I wouldn't think the weight change on THAT pulley would make the advertised changes, either...

I think I'm probably going to stick with my OEM pulleys after reading the posted write-up...but I still wanna know how/why they can even think to make the advertised power gains...