Hey everyone, i was wondering i have a m6 and was wondering what everyone thought on gettinga performance underdrive pulley, what brand have you guys been going with and where did you buy it from.. any horsepower gains? what does a pulley do in general

 

an underdrive pulley, since it's smaller than the stock pulley, is easier for the engine to turn and leaves more power to be used for other things...

...your signature... gross! lol

 

if your looking for one you can check out the parts classifieds and if nothin there take a look at the sponsers to see who has the best price all brands of pullies will pretty much be the same

 

asp pulley has always been popular!! but im thinking of going with the slp pulley. i hear its a good product.

 

Isn't it true that with an underdrive pulley everything that runs off the belt operates slower and it can cause problems with your alternator keeping up the charge especially if you are drawing alot of power.

 

Some people replace the alternator crank pulley for a 25% underdrive as well. That may cause power problems. I haven't heard any problems with just the 25% underdrive crank pulley.

 

Not true, sometimes auto cars may experience some surges.

I got the ASP, the SLP I think is the same thing as the ASP, the 25% and higher walls for reduced belt slip. I wish I wouldnt of got it in a way, I wish I would of just waited to get it when I get my cam eventually. You will pick up a little bit of performance, I really didnt notice alot. But when you get a cam I think its essential.

 

SO WHEN YOU SAY UNDERDRIVE PULLEY, do i just buy the asp pulley or do i need anything else?

 

You need the pulley, a new GM crank bolt or ARP bolt (reusable but expensive compared to stock ~$25), and a new belt that is the, new, correct length (I believe if you buy the pulley from most vendors they tell you what part number you need). You will also need to go to autozone and rent a pulley puller if you are going to do it yourself.

Side note I haven't had any issues with my ASP Pulley as far as charging and what not. If you run big stereo stuff they make an overdrive alternator pulley to compensate.

 

thanks 777

 

If you have a 99 ls1 I say spend the money on an ls6 intake manifold (if you dont have one) over the pulley, then if you go cam then pick a 25% pulley up as it will add a good 5-10 rwhp. On a stock car i have felt more of a power gain with the ls6 intake over the pulley.

 

Has anyone noticed reduced Air Conditioner power after installing a pulley? I live in Phoenix Arizona and its around 110° today!

 

It can take a little longer for the a/c compressor to kick in sometimes. On an automatic car, I recommend the over drive alt. pulley all the way, takes strain off the alt. If your car is close to stock, or with newbie bolt-ons, I would not go out of my way to install this unless you have the timing cover off for a cam change. There are better gains to be had elswhere on the engine, like the ls6 intake, or installing #243 head castings.

 

asp pulley here works great

 

I have the ASP underdrive carank and alt pulleys and havnt had any problems. i didnt notice a huge seat of your pants improvement but i did pick up 2 10ths at the track the day i put them on!! ( could have been the weather conditions or somthin else tho). i did notice about a 2 MPG increase tho! i know that ASP says that they pulleys increase MPG and for me it really did.

 

It's typically understood it's worth 1-2 tenths off the quarter but hardly any gains on the dyno.

 

+1 no issues here either We had to change belts also(2).

 

I had a March crank pulley put on mine last year (I say this because without having the car on a rack where I could stand underneath it and put some shoulder into it, there was no way to get the crank bolt loose...not even two of us. The shop had to use an air ratchet.)

You will notice minimal power gains, but for the small price its not a bad move.

You should not notice any power surges or fluctuations.

PS I ordered my pulley from Thunder Racing (Love those guys!) It came with pulley, bolt, and the two belts!

 

With a stick car I don't see why an underdrive pulley would be a charging problem. The ASP pulley has an alternator pulley anyways. Just get another belt and order the ASP pulley and you will be fine. I'm SURE you will see some pick up in fuel milage too. I did. The crank bolt is ok to be reused. I mean it is not like he is running a supercharger.

 

I gained 14rwhp & 12rwtq with the SLP (march, Powerbond) 25% underdrive pully.