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why wierd power???

GTR 94

By GTR 94,
in Engines & Forced Induction

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GTR 94 Mentor

GTR 94

Posted
Posted

well finally got my r33 gts t to the dyno not heavily modded just stage 2 FMIC, apexi safc, 2.5 inch from the cat back exahust and 12 pounds of boost i obtain a 190kw at the wheels. "HAPPY? i dont know!" the guy who was tuning said he has never seen such an ugly power curve! from 4800rpm the curve is perfect shooting straight up but before that, it looks like a stair way all lumpy and shit at 4200rpm to 4800rpm it actually flat lines making no power. WHY IS THIS!!!

also how come on 7 psi at 4000rpm it makes roughly 138kw but at 12 psi at 4000rpm it makes roughly the same. a little help would be great.

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gtrhybrid Contributor

gtrhybrid

Posted
Posted

Your turbo is too small. It takes more that you think out of the small t25 to keep up with the rb25's displacement and rpm's. This creates lots of extra heat going into your motor reguardless of the intercooler. May sound comfusing to you but I can almost gurantee its the problem. Why do you think the turbo makes boost so soon? Its too small.

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Gradenko Mentor

Gradenko

Posted
Posted
Originally posted by gtrhybrid

Your turbo is too small.

Er, no. Note his problems are before 4800rpm, not after. The turbo is a T3, btw.

ECR 33, the 4500rpm flat spot is a common problem with 25t's, but a safc + tuning usually sorts it out for most ppl (myself included). The factory ecu runs super rich and takes out a bunch of timing at non-stock boost levels. Cutting back fuel (afm load) on the safc should have corrected it. Does your tuner have much experience with rb25det's?

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benm Grand Master

benm

Posted
Posted
Originally posted by ECR 33

2.5 inch from the cat back exahust

I believe your problem is this.

Replace the current exhaust with a 3" Turbo-back system and you'll gain a good 8-10rwkw across the board with noticable power gains in the 2,500-4000rpm area by freeing up the turbo and allowing it to breathe.

I created a thread here somewhere of a "before / after" dyno readouts when I got my standard front/dump/cat replaced with a 3" system. Ahhh here we go you can read up on it

here

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