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Tuner Think I Need An Exhaust Cutout Valve

cobrAA

By cobrAA,
in Engines & Forced Induction

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cobrAA

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In a lifespan of 18 month ( ish!) and about 7000 kms. My car produced 70whp less on the same dyno, same setup.

- Timing : we thought we skipped a teeth, but I didn't.

- Turbos : Mechanic said I have a oil seal leaking which means the turbos are wearing out prematurely, maybe I lost a few whp/spool right there.

- Compression : we did a dry test and some were 145, while other were 160 or 155. My mechanic then told me I should re-do the test with oil and see if I don't have a bad ring because a 15psi variation is huge in his opinion. I could be loosing WHP here..

- Exhaust: I have a very quiet exhaust, all my GTR's friend tell me that. I live downtown and want to draw little attention from cops so I'm quite happy with how my GTR sound. The system consist of R34 dump pipe (58mm), downpipe 2x 70mm to 1x85mm, ultra-quiet resonator 80mm ( which replace the oem cat), straight piping to a 80mm ultraflo muffer straight, to finally exit by a 80mm varex exhaust.

He think that the fiberglass packing inside all these resonators/muffler could wear out and create some sort of turbulance which could result in a slower spool and maybe a 20-30whp lost.

I'm not really interesting in going 2x70mm to a 1x90mm because I'm happy with how the exhaust sound and spend good coins for all theses components. But I thought, I could probably just install an exhaust cutout valve before the resonator. OR I could buy another resonator and swap my muffler with new unit.

P.S: For people who remember my desire to go single with a EFR and such.. with the lower compression my motor is pulling, I'm leaning toward putting my money on a rebuilt engine than a 7k turbo kit and I thought while I'm rebuilding the engine, might as well go with a stroker kit :)

cobrAA Mentor

cobrAA

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Don't guess. When you are on the dyno unbolt the exhaust and see if the 70kw comes back.

How much will you pay for a stroker kit? For me RB30 is better value for money.

Totally agree. However, before spending some coins.. ( mostly around 100$) just to get it on the dyno, i thought i would ask here if anyone ever experimented this kind of ''symptom'' before.

Fitting a rb30 under the hood is no fun AND RB30 are really not as cheap as it is in Aus. We pay a lot more for these + all the shipping involded.

one that has your power curve, fueling, and MAP.

I actually don't have anything ( well.. i didn't ask him when i left the dyno at 2am) but could ask him to send me some data by email.

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