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boost dropping RB20DET

Doctor 30

By Doctor 30,
in Engines & Forced Induction

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Doctor 30 Community Regular

Doctor 30

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My DR30 runs 14.5psi from the RB20DET when the engine is cold to just warmed up but as I drive it steadily drops to 11psi (9 psi when it is hot summer.) Is this a cracked turbo casting, a dodgy waste gate or under bonnet temps causing it to struggle (no cold air induction on this, all straight from the radiator).

Sometimes it boosts a PSI higher before it drops down to its set level which makes me thinks the computer is sensing detonation and bleeding pressure in response.

Has anyone had these problems with a R32? Are there any common problems with this engine & turbo (My RB20DET is the silver top ECCS which is from the R32 GTS)

Thanks

Robert

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bbenny Mentor

bbenny

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two possibilities,

firstly the std RB20 turbo doesnt flow crap, so i wouldnt expect it to hold 14psi all the way to redline, it will more likely spike then drop a couple of psi, as your engine gets hot the ECU will alter the ignition timing which will change boost levels/response.

I know when i tuned my car on the dyno i would set my boost controler at 38 points which would make 1.1bar on the dyno, after the tune i double checked this setting on the road and my car was still hot from all the dyno runs, it made exactly 1.1bar again. then that night it was much colder and boost jumps to 1.2 with the same 38point setting on the boost controler. the air temp and motor temp will vary the timing determined by the ecu.

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Doctor 30 Community Regular

Doctor 30

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Found a small brass bleeding nipple between the compressor and the waste gate, I plugged it and boost dropped to 12psi from 14.5psi, but the car is more responsive now. I think I just need a better turbo, anyone got a spare turbo they can lend me..............

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