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Thread: YB horrendous noise when on boost

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    Bodger

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    YB horrendous noise when on boost

    Just rebuilt my cossy YB motor, nothing special rebore with wossener pistons head light skin and the block decked to give 8-5 to 1 compression ratio. The 350 kit from BHP and rebuilt turbo T34 from BTN. But when it comes on to boost approx 2700rpm the noise starts. I thought it was the vanes in the turbo catching on the case it's that sort of noise, take your foot of the gas and the noise spools down just like a turbo would. Stripped turbo down with the OK from suppliers cannot find any thing catching within the housings. Would the compression ration at 8-5to1 cause detonation? Car starts fine ticks over fine. To stand and Rev the engine you can hear a slight similar noise but nothing like it is when it's under load. Any ideas

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    Mechanic

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    Re: YB horrendous noise when on boost

    If we hope or assume the problem is not engine related based on your description...first obvious thing to be looking for is air leaks.

    Whether boost pipes, IC, couplers, dump valve, intake manifold etc

    As a test you could undo or remove a boost pipe and try the car basically n/a
    9.85 @ 145mph 202mph standing mile

    https://www.youtube.com/watch?v=Ss_c7fML3rw

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    Tyre Wall Terry Decade Plus User 4parajon's Avatar

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    Re: YB horrendous noise when on boost

    Has it been mapped??
    Who mapped it??

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    Bodger

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    Re: YB horrendous noise when on boost

    Nothing has been altered re ecu (L6) apart from the fitment of chip supplied by BHP. Was hoping to get up and running put a few miles on it then put on RR for setting up. Did do the couple of miles with no air filter on, so could it be the amount of noise created by the turbo on this spec ? When it does come on boost at only half throttle it get well on its way, but the amount of noise I've not heard before and when you've sunk a load of cash into an engine it was more than worrying. To me it sounded just like if you got a hairdryer and stuck your fingers across the fan while on full speed if you get what I mean.

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    Re: YB horrendous noise when on boost

    Quote Originally Posted by Colr6 View Post
    . Did do the couple of miles with no air filter on
    has it done since you stripped the turbo down and put back on ? Maybe you sucked something in the turbo. An air filter to me would be wise.

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    Bodger

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    Re: YB horrendous noise when on boost

    I stripped the turbo and found nothing, spoke to BTN and it's going back for them to check. It's not a two minute job to take off and on. Only ran it without the filter as the original air filter hose wouldn't fit and only did a mile and half at most! The man at BTN did say they had a golf experiencing the same problems with excessive noise. Could it be the turbo is spooling up that quick the air demand is not big enough so it was like exhausting out of the inlet? With having no filter on it the noise would be multiplied ? Problably me worrying about nothing ( hope so!)

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    Racer Decade Plus User

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    Re: YB horrendous noise when on boost

    From the description you've given, it sounds like compressor surge. You are putting too much airflow through and it is backing up into the compressor. If it is surge, you don't want to be driving it like that.

    Does it sound like this?

    https://www.youtube.com/watch?v=nCj6Spwl1CU

    This one is more informative

    https://www.youtube.com/watch?v=vuyJ5jD3r0o
    Last edited by Montyman; 17-05-2018 at 17:01.

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    Tyre Wall Terry Decade Plus User 4parajon's Avatar

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    Re: YB horrendous noise when on boost

    Personally, I wouldn't trust ANYTHING bought from BHP. If it wasn't doing it before & it is after you've fitted there chip, then there is your answer.

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    Spanner Monkey

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    Re: YB horrendous noise when on boost

    or the exhaust housing and/or wastegate is too small for the application

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