Thread: Pulley size question

So my setup is in my signature and I was curious when you drop pulley size from like a 3.4 to a 3.3 would you need alot more fuel or change the tune? Or is it possible for it to work I've only ever had a 3.4 and I've always had 0kr and the air fuel is good.

It will be fine. Your maf reads you have more air coming through, so it will compensate with more fuel.

Do you think I could get away with a 3.3 pulley or could the kr go through the roof? How much is a .1 of a drop as far as boost/power? I did a top swap and only ever had a 3.4 on the car never even had a stock 3.8 or whatever so I have no idea lol.

Originally Posted by GTPpower

It will be fine. Your maf reads you have more air coming through, so it will compensate with more fuel.

That's the hope anyway, maybe.

But it's still possible to run lean if the maf calibration isn't just right, he might hit a certain maf hz where it could lean it out. But I doubt you'll gain more than 1 psi with the small pulley drop.

If you have 0kr, you probably can drop to a 3.3. It won't make much of a difference in boost level or power. You probably can't feel a difference without a dyno.

I'd try it. If it doesn't work, go back to a 3.4.

If it's that little of a drop could it even go that lean? So your saying not even a noticeable difference in power?

Originally Posted by Fivefingerdeathpunch

That's the hope anyway, maybe.

But it's still possible to run lean if the maf calibration isn't just right, he might hit a certain maf hz where it could lean it out. But I doubt you'll gain more than 1 psi with the small pulley drop.

If his afr is good now, dropping .1" on the pulley size isn't going to change anything.

Originally Posted by Tonkin2000GT

If it's that little of a drop could it even go that lean? So your saying not even a noticeable difference in power?

Maybe 5-10 hp.

Okay because I had 0kr with a plog setup and I just now installed my slp headers so I figured I could probably get away with it and like you said if not I'll just put the 3.4 back.

I'm currently running a 3.2 on my setup with about 6* total.

Originally Posted by torq455

I'm currently running a 3.2 on my setup with about 6* total.

6* of kr? thats no good.

6* of kr?

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Where is chip?

no kr chip.....dead fuel pump caused this one. so it must of got a touch right lol

Who's motor is this?

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thats my l67. had rockers and a 3.4, headers. fuel pump took a crap leaned it out and hello you sob you chip. it popped at the top of second gear at the shift. it made some funny sounds, and i knew it was hurt asap.

funny part was i planning on swapping it out 2 or 3 days later anyways, plan was to have a running spare. my brother saw it like this, i was cheating on my engine building the new one, so it dumped me.......just like a scorn chick lol

****ty did you have gauges or did it just happen that quick?

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i had the t app running saw nothing, it was tuned pretty good, no kr at all. wish i had the wideband hooked up, but that got bought and installed with the new engine.

didnt figure out the pump was bad till a 1000 miles later on the new engine too. i had it tuned in rough and the new pump made my ltft go from -0.8 to -2.8.

What does the t app show? Is it like a aeroforce? I'm assuming that happened during wot? When your reading stft and ltft is that really critical to moniter all the time? Is it normal for them to fluctuate alot? I know the closer to 0 is where you want it to be but how critical is that?

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fuel trims are read off the narrow band o2, so not 100% accurate. but works.

neg numbers are rich, pos are lean. wot the ltft will lock in and stay at one number. 0,0 is the goal, ideal you want it to run -5 and lower at idle and cruising around under normal driving. its better to be a tad rich as you go wot.

if i get my ltft to lock in at -1. something wot i leave it like that. i rather a tad more fuel then not. right now im locking in at -3.1 wot, need to lean it out just a bit more.

stft should be close to 0.0 at idle, and lock in at 0.0 wot. idle and normal driving it will dance around.