Thread: what pulley size should i go with?

Right now i have a 97 grand prix with an SLP cold air/ram air set up i have a 2.5 catless down pipe and thrush glass pack resonator with stock mufflers that i am going to be putting on some time this week, im also ordering a plog from another member on her and im planning on giving it a tune and new plugs before i drop my pulley size. i know a little bit about KR and all i dont have a scanner for it though. i have a 3.4 pulley (not installed) so if i get all this done do you think i could run that size pulley? if not what size would you recommend?

2.5" DP is worthless on these cars.

Get headers instead of wasting money on a plog.

Headers -- 3.5 pulley

Plog -- Stock pulley or 3.6 pulley running rich.

2.5 catless dp? and a plog im getting for 60 shipped i dont have the money for headers or the skills to install them. but im pretty sure if i did put headers on i could run a 3.4 with 0 kr, i would think.

Not even close.

I had to run my L67 stupid rich (low 10's AFR) not to knock on a 3.4 with just headers/intake/full headerback exhaust (no cat)
When i added rockers/springs i was able to lean it out to 11:1. It still complained (knocked) in the winter. This was all running 93oct.

More boost = Lack of flow.

3.6 might be the best you can do with that plog while seeing decent timing at a decent AFR.

Originally Posted by gtpeddie

2.5 catless dp? and a plog im getting for 60 shipped i dont have the money for headers or the skills to install them. but im pretty sure if i did put headers on i could run a 3.4 with 0 kr, i would think.

Are you buying the plog on sale here? You do realize it has to be rewelded right? That has it's costs too. You can buy headers for a touch under $200. Install isn't as hard as it seems.

well you would know more i just thought headers would be good enough, but for that plog i have a MIG/GMAW and have access to a TIG so either way i can re weld it thats not hard for me. my concern with headers is getting to the back of the engine.

Originally Posted by Nixon

Not even close.

I had to run my L67 stupid rich (low 10's AFR) not to knock on a 3.4 with just headers/intake/full headerback exhaust (no cat)
When i added rockers/springs i was able to lean it out to 11:1. It still complained (knocked) in the winter. This was all running 93oct.

More boost = Lack of flow.

3.6 might be the best you can do with that plog while seeing decent timing at a decent AFR.

So because your setup couldn't support that size pulley....... that means he can't?

To the OP, with those mods you are right on the line of what is normally necessary to support a 3.4 pulley. A 2.5 dp is small, but it certainly isn't a "waste". And the plog is nice if u can get it for the right price.

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You realize Jason that these engines aren't getting younger. They can't quite hold up to the boost they might have once been able to hold up to.
I'm offering the guy safe advice based on my modding AND tuning experience. Better safe than sorry.

The most sensible recommendation here if you're pulley happy is a 3.6 accompanied by a good customized tune.
Get a aeroforce interceptor to scan for knock proactively.

thanks for the advice guys, and i wish i had an aeroforce interceptor but there so expensive and i have no idea how to hook one up but that is on my future modification list once i start working more over the summer once i graduate from school

Keep an eye out on the forum, they occasionally pop up for really reasonable prices.

Originally Posted by Nixon

You realize Jason that these engines aren't getting younger. They can't quite hold up to the boost they might have once been able to hold up to.
I'm offering the guy safe advice based on my modding AND tuning experience. Better safe than sorry.

The most sensible recommendation here if you're pulley happy is a 3.6 accompanied by a good customized tune.
Get a aeroforce interceptor to scan for knock proactively.

Well, I disagree with ur argument that older cars can't handle as much boost..... but since he has no way to measure KR, I agree with a 3.6

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yea ill probably try a 3.6 ill run the 3.8 for a while this is zzp's take on it


" 3.4" for 97-00 GTP/GS with ZZP PCM, Tstat, colder plugs, bolt in downpipe, and a cold air intake. "

ZZPerformance - Press-On Supercharger Pulleys #ZZ-PRESSPUL

Zzp also says you can run 3.5 on a stock car... shows sometimes you cant trust them.. if u want the best advise stick around here these guys are giving great advise in first hand experience

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yea i know i havent been on her for to long but i been asking alot of questions and posting alot

If money is a big issue then stay stock.

its not that big of an issue it just take me some time to get parts cause i try and find deals and im not working as much durring the school year once summer hits is when ill have more money to buy more parts at a time i already have a good amount of parts i just get them little by little

If you have an android phone you can get a obd2 to bluetooth adapter and download the torque app and you'll be able to scan for KR. It only costs between $20-$30 if you buy a cheap adapter.

I heard that doesnt scan kr

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It does I have it. You have to have the paid version though.

Ahh sweet now i will invest lol

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