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3.5" Pulley

C

conpeez9

New member
Hey guys!
I apologize if a thread similar to this was already posted. But I was just looking for some help with smaller pulleys for my 98 Grand Prix GTP. Currently I have colder spark plugs, 180* thermostat, and a cold air intake. I was wondering if I were to move down to a 3.5" would I need any more supporting mods? Or would I be okay. I originally had planned to just move down to 3.6", but I figured a 3.5" would give me more power, and I still wouldn't need all the expensive supporting mods. But I am not sure on that. If you could leave a comment with some help, that would be great!
Thanks,
-Connor
 


Quick answer is, no you can't put it on there.

I sure a whole bunch of dudes are going to jump in here with some wild opinions and lists upon lists of mods that MUST MUST buy to get to a smaller pulley.

The quick and dirty is flow, get more flow out and then add more flow in. Search around for modding threads and you'll figure out quickly that a set of headers or a plog/dp combo is what you'll want to buy first.
 
Give this a read. Don't skim through it. It is the 3800 Modding Bible. Years and years of trial and error, new technologies, and the best minds have put this together. Granted they were probably heavily intoxicated at the time, but it's still basically law around these parts.

http://www.grandprixforums.net/threads/67580-Safely-Modding-Your-3800!


Quick summary, No you will lose power dropping to the 3.5. You are more than likely already knocking (air/fuel mixture is detonating before it's proper time, causing a loss in power and a hammering effect on the piston) which will pull timing to try and adjust for the knock, reducing power. Drop to the 3.5 and you'll just increase the knock which = less power.

Need to open the exhaust up. Headers or a PLOG/DP combo are the go to choice. After that, help it inhale with a homemade intake. Then consider dropping pulley sizes and getting it tuned.
 
The only way to truly know if you can drop pulley size is SCAN SCAN SCAN. Get yourself a 20$ bluetooth OBDII adapter, and download torque on your phone, it can tell you KR and lots of other fancy things, or get a aeroforce gauge, or one of the many other scanning tools available for our car, torque and the BT adapter is by far the cheapest, if you have a smart phone already. There is no way to know for sure if you can drop a pulley without being able to see KR, sure you can guess and check, but like machinegun said, you might be losing power if you're just increasing KR with the smaller pulley.
 


SnowTh1ef said:
The only way to truly know if you can drop pulley size is SCAN SCAN SCAN. Get yourself a 20$ bluetooth OBDII adapter, and download torque on your phone, it can tell you KR and lots of other fancy things, or get a aeroforce gauge, or one of the many other scanning tools available for our car, torque and the BT adapter is by far the cheapest, if you have a smart phone already. There is no way to know for sure if you can drop a pulley without being able to see KR, sure you can guess and check, but like machinegun said, you might be losing power if you're just increasing KR with the smaller pulley.
Click to expand...

You know this better then most considering you somehow are running a top swap on a 3.4 with no KR and ZERO SUPPORTING MODS... WTF.
 
Not zero.. the blower is fully ported and I'm on a 3.6 right now lol. Could definitely run a 3.4 or mayber lower on corn.
 


Well I'm still able to run a 3.6 with almost no KR.. and i like the extra milage, and the corn stuff isn't any cheaper than 91 where I live :(
 
Yeah, that's how it is on the east side of the state where I used to live, but now out on the west side, much more expensive. like 3.50/gal or more.
 
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