I have been noticing that more pulley manufactures are making pulleys by .1" increments. I was going to buy a 3.4" pulley but I am thinking about the 3.3" now. A couple questions...

What additional gains in boost, HP, ft/lbs would you expect over the 3.4"?

What pulley belt would I want to use for this? Part number would be helpful..

Would I be able to put a 3.3" pulley on my car with only a 180 stat, pcm, and maybe a CAI? If not, what else would be needed?

Also, I cant decide between thrasher or pulley boys.. Anyone have any opinions??? Which is better.. Im not interested in the ZZP pulley because i personally dont like the way it looks.

Thanks alot.

When I talked with Zoomer of zzp he said the 3.3" would give me about 1/2lb of boost over the 3.4" but that was with headers. Without headers I think it may be 1lbs?
6PK1815 Gatorback SC Belt will work for 3.1 to 3.5, about $25.
To go with the 3.3" you really should complete the exhaust with cai, free up some flow to offset the boost and reduce knock retard.

OK, with the mods you have you shouldn't really run a 3.3". I would go with a 3.4" until you get some exhaust work done. (a cam, rockers, headers, or other mods like that) Otherwise you will have some pretty serious KR problems.

Personally I would get a ZZP or Pulley Boys system before a Thrasher. My dad had a Thrasher on his GTP and it became a problem pretty quickly because the thrasher systems are only available with 4 pullies (3.4", 3.25", 3.0", and 2.8"). The ZZP system has pulleys by a tenth of an inch increments, and IMO is the best system despite it not being the best looking. I definately think the Thrasher system looks much better than the ZZP system, but the ZZP system is much more practical. Thats like buying a neon to pull your trailer with because you think it looks better than a truck/SUV. (not that I think neons look good, just making an example) I don't know much about the pulley boys system, but I have been told they will make any size pulley you want, so I guess if you like how it works, that would be the system to go with.

Shawn

Basically, if you are going to go with a 3.3, you want something that'* gonna make the engine breathe better, and then get colder plugs.

i have had a 3.3 pulley on my wifes car for over 30k miles
we love it
i also have a 180 therm , and a low backpressure cat back exhaust
the car runs 14.4 in the 1/4 mile @ 96 mph
stock air box and intake, get the 3.3.

Did u get colder plugs?

yes, ngk tr 55 ix

And I would bet large amounts of money it gets a decent amount of KR on pump gas too. If you put on a 3.4, the car wouldn't get any slower, I can tell you that almost definately. Do you have a scantool? What do you use to tune the car with?

Even KR as small as like 5-8KR is HUGE. Before the intercooler on the GTP we went from a 3.25" pulley to a 3" pulley just to experiment, and the car was REALLY REALLY slow with the 3" pulley. It had a lot of low end torque, but the power fell off, FAST. According to the autotap the car was only getting 7kr with the pulley. I would bet that with the stock SSEi PCM you are getting 5-10 degrees of KR somewhere, and if you went up to a 3.4" pulley, you would be suprised. A smaller pulley just shoves more air and hotter air through the engine.

I know before I would go smaller than a 3.4" pulley I would put a scantool on the car and make sure it had no KR. Unless it was REALLY REALLY modded with like a cam, headers, and an intercooler or something. You can never be sure without scanning it.

Shawn

From dyno testing that i have done (and watched) each .1 is about 1 PSI boost. And each PSI boost equates to about 10-12 HP at the Wheel. 3.4 is the first step I would take (and maybe even a 3.5 if your car is freaky with the KR). And once you have supportive mods for intake and exhaust you can move down. What you want to avoid is boost stacking. The boosted air can't exit the car fast enough and the hot air remains in the engine causing heat soak. This will cause the car to pull timing and reduce your power. Anything beyond a 3.4 without supportive mods can adversly affect your performance even though you are adding almost 4 PSI. With my 3.4 and rockers and intake I still see about 3-4 KR at WOT. I'm hoping my headers next week alleviate the boost stacking and reduce my KR to 0 at which point I will go with my 3.2 and see what kind of KR if any I get with that.

i borrowed a 3.4" pulley before i bought my 3.3" pulley
my track times were a best of 14.59 @ 95.188 with the 3.4"
my car is quicker with the 3.3" pulley on it .
buy just the hub and borrow different size pulleys
to find the one that works best on your car
go to a track in your area and talk to the L67 people
i'll bet you'll find most people will be glad to help. Goodluck .
Rod