Well everybody on the GTP forum reccomends that you go to a 180stat, one step colder plugs (Autolite104s), ported exhaust manifolds, free flowing exhaust such as a full 3 inch downpipe, PCM tuning such as HP or a powertuner would be optimum. You could probably get by with a easy performance AFC 1.1 or a 2.2. Are you running OBD I or OBD II? Just wondering because you need to be able to scan for KR somehow if you drop any size in pulley. If you are running OBD II then you could scan with the Aeroforce Interceptor 2 1/16 in dash scan guage or you could watch over on ClubGP for a Palm Scanner such as the one that mustangsbware is selling in the mall here. If you are running OBD I then you have to use a laptop with a scanning software that i believe can be downloaded on the internet. All of those mods i listed above are just a rough estimate of what you need to run a 3.4 pulley. Every motor is different, and there have even been some stock GTPs that are showing KR on a STOCK pulley. So i would say that if you have no way to scan then i wouldnt drop any pulley sizes yet. You need to scan and see if you are registering any KR currently. I understand that the 3800SC in a GTP is alot different than in a fiero but i still stress that you need to scan it first so that you dont risk chipping a piston or worse. Hope this helps. Daniel
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07:39 PM
Mark A. Klein Member
Posts: 608 From: Pleasantville IA Registered: Aug 2002
If you have a manual car, I would say with a performance minded exhaust and intake, you could easily run a 3.3 or 3.2 pulley WITH TUNING. You will make a bit more power, only if you run your car a bit on the rich side. My auto runs right on the edge with a 3.4 pulley, running alot of timing and lean afr.
Its VERY hard to compare even automatic swaps into fieros with the GTP tanks, they create much different load and exhaust/intake characteristics than most fiero swaps.
Safely go with a 3.5 and make it a modular one so if you do some mods down the road it is easier to change the pulley to a smaller one. I have seen some stock engines run with the 3.4 with no KR and some have KR through the roof with just the 3.4. Your swap has a healthy engine with a nice flowing exhaust, manual 4 speed tranny and already has a 180 thermostat and a good tune so a 3.5 will work fine with the set up you have. To run a 3.4 or lower you need mods to match and the PCM retuned as well. If you want to get a pulley then drop by one day and I can change it over for you and do a complete check on your car while it is here, of course it is all part of the warranty so there is no charge. Dan
I believe that you can keep your engine together with a 3.4" pulley with the supporting mods as I have on my engine as listed below. It is my opinion that a nonrestrictive CAI system is critical. As boost rises, you'll want to keep those intake air temps as cool as possible so that KR stays in check . My setup brings the air to the TB via a side scoop so it guarantees that we are bringing in the colder outside air. That being said there is still no substitute for continual scanning, data logging and PCM adjustments. With the proper fuel and spark, the 3.4" pulley should pose no problem.
------------------ 87GT - 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles 87GT - 3.4L Turbocharged engine, modified TH125H " I'M ON THE LOOSE WITHOUT THE JUICE "
