do underdrive pulleys really help? Options

[nate95]

Just curious if any body had put an underdrive pulley on there car, and how much of a difference it made, or how much HP you gained,, thanks.

[celicaST]

Just curious if any body had put an underdrive pulley on there car, and how much of a difference it made, or how much HP you gained,, thanks.

first off, you are NOT going to gain any horsepower. only way to gain more power is to burn more fuel, end of story. what you will gain though is engine response as there is less rotational mass for your engine to turn as it revs up. this is just like installing a lighter flywheel or reducing the weight of your car. your engines power puts energy into both accelerating your car forward and acceleraing the rotating components in your car. so technically it will make your car quicker, but think about it... a few lbs of weight off of the underdrive pulley is very minimal percentage wise (add up the mass of all rotating comonents: gears, axels, wheels, crankshaft, etc). i dont have one, but im willing to bet you wont notice a difference at all. dont be a fool for marketing, in my opinion that money can be better spent at making your car faster.

This post has been edited by celicaST: Aug 5, 2006 - 3:53 PM

[Fastbird]

first off, you are NOT going to gain any horsepower. only way to gain more power is to burn more fuel, end of story.

I didn't see it posted, so I thought I'd clear up a point here. The above statement is isn't ecactly right (don't get me going on the burn more fuel part). Yes, you can "gain" power by putting an underdrive pulley on a car. However, I quoted gain because it's not a overall gain in the normal terms, but rather the reconstitution of parasitic power losses by the motor not having to work as hard turning all the accessories.