imshawn88

i see many sites selling under drive pully's. i just dont exactly know how they improve hp. any one who has bought one, was there an improvment and how much? thanks for anyones time who responds.

imshawn88

i drive 2001 elantra the pullys i've seen are from unorthodox and aos.

BV1

I got it, it gives a low end torque improvement, espcially in 1st and 2nd. Dont expect to win a 1/4 with it though, another stock can still beat you if he gets a slight edge on the start. It only gives 2HP top end.

-Steve

JonGTR

I have it. I have more detail on it on my site in my sig (be patient with the pics, they will load). I did many before and after trial runs and it seems that it dropped my 1/4 by 1/10th of a second but my trap speed was 3mph faster. I may need to do a few more runs with it.

MeetTheCreeper

An underdrive pulley is meant to decrease the overall speed of your belt driven accessories so that they are not robbing you of as much power from the engine. It does not really make your engine perform any better, it just gives power back that was already there. By making the crank pulley larger and tweaking the other pullies, one can make the overall speed of the accessories slow down, or at least made easier for the engine to turn them.

An overdrive pulley is generally for superchargers and blowers. It DOES make your engine perform better. By decreasing the size of the pulley on the supercharger. The speed of the blower increases and produces more boost to the engine and therefore more power.

Does that help at all?

DESIGN

Besides the underdrive effect the afftermarket crank pulleys also are much lighter. Based on the principal of rotational mass a lighter pulley means that more power gets to the wheels.

JonGTR

I'd say that it was at least 5 lbs. lighter and about an inch smaller in diameter.

imshawn88

thanks everyone that helps out alot. now i will need a smaller belt when i buy one, correct.

CyberShark

I thought Random was trying to get a hold of some pullies with the damper included?