i know this is probably like the 1000th post about a pulley upgrade...i did search but i didn't get all my answers from one thread and not in the mood to sit here and hours to find my answers...anyway im looking to get a pulley upgrade for my 05 S...all thats done to the car is intake and exhaust and its automatic...what would u guys recommend reduction % size (i want a alta pulley). i want it to make good power but nothing too crazy to damage anything.

also do u need to change any belts or anything or is it a "bolt on" and can anyone in the socal area install this, or at least give me a hand?


thanks
-Fred

 

15% and 17% is the norm. Some of us run the 19%.

as far as the belt, 15% can use the stock belt.

 

what kind gains would i get with a 15% upgrade?

 

Like 15 whp

 

if i want to do the 17% what belt would i need?

 

Here's a 15 vs 17% thread.

Note that with the auto, there is less space (pulley is closer to the engine bay) so the install is a bit more arduous.

 

I run an alta v2 15% and gatorback belt(4060537)-summitracing.com.
-me like

 

The general consensus is that if you're going to drive your car hard or track it at all, stay away from 17 and 19. They sometimes slip because they're much smaller than stock and it makes the belt work pretty hard to get a grip if you're driving quick.

I'd change the belt no matter what you get. JCW Changes the belt with their pulley, why someone would throw a 15% (bigger reduction than a JCW) on their car with the stock belt just perplexes me. Do you HAVE to? No... but your car will probably perform better, because your belt won't slip, and it'll last longer. (Oh, and if it does break, due to an amazing design, the tensioner will slam into your crank pulley and probably break it )

My vote: 15% with smaller belt .

 

Negative on that Ghostrider. With a 15% (or greater reduction) the stock belt cannot be used...either NAPA 060539, 060535, or Gatorback 537. You'll get slip if you don't, and the tensioner will be out of or at the upper limit of its range as well.

As far as which reduction to go with, the 15% puts it more within the supercharger RPM specs, is still safe at redline, and is more efficient at redline as well. There's a little subjectivity to this call though; if you don't spend much time near the upper RPM's, the 17% or 19% can have the supercharger in a useful range earlier...but you should try to stay away from higher RPM excursions.

I like to keep my car "safe" in all RPM's though.

Oh, and the reduction pulley is, for all purposes, a bolt-on. A cooler range of spark plugs can be installed (the JCW package does with a cooler range, and that has an 11% reduction), but I have no evidence so far that I'm pulling timing or melting the electrodes and I'm running the stock plugs. As well, injectors can make things a little safer...you won't be running at the upper limits of the stock injector capability. Without a tune you really won't go lean, but you are exceeding the intended duty cycle of the injectors in their original usage.

I have yet to run injectors with my 15%.

Hope this helps.

- Matt

 

Don't quote me on this because i have a manual with a 15% because i like to rev it, but this seems to make sense to me, if you're driving an automatic you might be fine with getting a 17% simply because the auto won't really be high in the revs for too long and you'll get more response and power when the box doesn't feel like downshifting. Just a thought

 

You still run into issues with belt slip due to the small pulley size, and by spinning the SC that fast you just make a lot of heat with no real gain in power. The SC turbine is already out of spec with a 15% pulley.