Medic949

I'm looking at optimizing the power of my stock 2002 Z06. I have seen under drive pulley upgrade packages claiming increase in power. Is there any truth to this and is the power increase worth the money?

PeteZ06

I think its good for 3-5 rwhp... I remember a few people dynoing their cars before and after installing an ASP underdrive pulley many years ago and that was the average. I ran one on my previous cars... not even sure if they make one for the LS7.. something I should look into myself.

TXGS507

I purchased one for my current 414ci.... Powerdyne...

IMO if you are going to change out UD pulley you may as well throw a cam up in there...

PeteZ06

You mean a real cam?

My LS7 is heads and cam but just a super small cam, I ran aggressive cams for too long in my previous cars that I really just wanted something tamer this round. Maybe one of these days I'll put in a healthy cam, get a LSX intake and drop my cats and break the 600+rwhp mark

TXGS507

you know what I meant PeteZ06....
I am opting for the aggressive cam, ported LSX intake, different fuel system, TEA's, Calloway Honker... etc, blahze,... I am chasing the 600 mark that you speak of.... Sorry to get off topic to the OP....

A "pulley" will be nice.... and inexpensive...

williamb81

I just installed one on my hot rod. Ill post the hp gains in a week or two.

ptindall

I installed one when my stock one started wobbling and threw the belt. I don't have a before and after dyno but I will say there was no negative side effect.

Moto One

I have always thought that the reason for under drive pulleys was so that you don't damage the alt/ac compressed from extended hi RPM runs. I was also told that if you are using your car for daily driving (commuting ect) you run the risk of not getting enough spin on the alt to properly keep the charging system at need levels.

Mark.

Scooter70

Is 3-5hp worth the hours of labor to just install a damper? (You need to move the steering rack out of the way to change the crank pulley. If you haven't done that yet, it's a pain in the a$$.) Like stated above, if you're going in that deep, you might as well spend the extra hour or two and swap the cam (and springs... and pushrods... and injectors.... and put on a FAST 92 and LS2 throttle body... and AFR heads....).

It's a never-ending series of "while I'm at it...".

skyavonee

ptindall

That and the water pump and power steering pump also turns slower opening the possibility of poorer engine cooling and insufficient pump pressure or volume when turned the wheel quickly. However, having done this mod, I can tell you that none of these occured for me.

PRE-Z06

Depends on how much they are underdriven and how much lighter, but I'd say ~3-8rwhp higher side being 25% reduction compared to 10%.