wondering what is a safe pulley size on my 98 gtp

[birar]

I have a 98 gtp i have a 3.4 pully, cooler plugs and a thermostat a reprogrammed pcm ,a k&n intake, pacesetter headers, and 3inch zzp exhaust i am wondering if i can maybe drop a pullie size 2 a 3.3 or a 3.2 safely and im also wondering if anybody has ran there car with the settup i have i wanna know roughly what i will run

[tblake]

I dont know....

I'd probabaly leave 3.4" wouldn't be worth sacraficing the motor IMO.

I think with anything less than 3.4 you need an intercooler.

[grandprixgtx00]

for anything smaller than a 3.4 your gonna wanna do a valve job,cam, and an intercooler

i wouldnt recommend doing any smaller than a 3.4 personally. even with a 3.4 you should have something in your car to moniter KR.

[BNaylor]

Before I provide a reply which will be different but probably not radically from the others what brand re-programmed PCM module do you have?

[birar]

I hav the pcm from zzp

[BNaylor]

Most of the basic or Stage 1 PCMs on the market will support a SC pulley as low as 3.20". The timing and spark advance curves and power enrichment tables are normally programmed accordingly. However, check with ZZP just to be sure. I run a 3.25" as an alternate street pulley. The key is you have to monitor for any possible knock retard (KR) running your current configuration and then with the smaller pulley. I would not go lower than 3.25" if your GTP is a daily driver. Also, although an intercooler is nice and will give excellent power gains really not necessary. As pointed out other supporting mods are needed. Headers are a good start but I don't know how well Pacesetters are designed to help control KR versus for example SLP brand, TOG or S&S. Other things you can do is getter a bigger throttle body (72-75mm) and be sure to use a TB spacer between the supercharger and throttle body. The supercharger runs hot when you employ higher boost. Proper intake mods help reduce KR as will exhaust mods. Other good mods short of going to an intercooler are a S Ported blower, polished and ported lower intake manifold, cam or simply high ratio roller rockers. At least 1.8 ratio. Further, 2.5" exhaust plumbing versus stock 2.25" all the way to the muffler helps. SC mods can be tweaked in further if you have a Powertuner either DHP or HP for reliable operation and the best power gains and least amount of KR.

When running a smaller SC pulley it is highly recommended to get a scan tool and/or scan gauge capable of monitoring KR in real time at all times just to be safe.