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Harsh Induction Noise At Around 5,000rpm

munchstagea
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munchstagea Mentor

munchstagea

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Stagea RB25DET stock as a rock.

Harsh induction noise at around 5,000RPM sound is similar to a fan belt slipping or loud air leak, have all the belts as tight as you would want them. Sound seems to be coming from turbo area, only at high RPM with a stab of throttle in Neutral. Happens on the road too when kicked down (auto box).

Have unplugged the BOV to see if that was where the sound was coming from but no luck, only just coming on to boost but it is definitely down that path somewhere. The car is freshly imported so has come to me with this problem so I can't shed any light on how it may have developed.

I am not going to flog it to see what happens, just wondered if any turbo experts out there could throw a suggestion in the ring? My Dad is a mechanic but has very little experience with turbos (I have less!), we are not sure where to look and want to avoid major pull downs for something that may be simple.

Any recommendations for a Turbo workshop in the Geelong area would be great too? Would love to have someone that knows their stuff have a look and listen...

Cheers

Luke

munchstagea Mentor

munchstagea

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would this be like a screaming sound?

I wouldn't say screaming... loud like a belt slip but not "holy crap, what's that?" loud... It doesn't sound right but not catastrophic at the same time...

Luke

QRI05E Mentor

QRI05E

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Hmmm... Have a look at the exhaust from underneath the car... Are there any pipes running off the waste gate/turbo that are cut off and vented atmospherically??? If so, you have a screamer pipe :ban: that’s the only conclusion i can think of if its an "induction" noise heard at around 5000RPM as that is when the waste gate is fully open... The screamer pipe is a separation of the waste gate housing from the turbo as to vent the boost pressure atmospherically, its meant to help increase top end power however is illegal in Australia... sounds awesome on large turbos... Let us know how you go..

Regards,

Sarkis

stolen_s15 Mentor

stolen_s15

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Posted (edited)

Also check your exhaust manifold, dump pipe and front pipe for cracks. I had a similar problem on my s15, once the turbo started really boosting it made a noise similar to what you describe. If your car ever scrapes or bumps over anything (speedbumps, ect) this can certainly happen, even tiny cracks can cause this.

Cheers

Nick

Edited by stolen_s15
munchstagea Mentor

munchstagea

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Also check your exhaust manifold, dump pipe and front pipe for cracks. I had a similar problem on my s15, once the turbo started really boosting it made a noise similar to what you describe. If your car ever scrapes or bumps over anything (speedbumps, ect) this can certainly happen, even tiny cracks can cause this.

Cheers

Nick

Will be investigating pipes and possibly manifold and turbo to exhaust gaskets, don't want it to be a turbo bearing!!! I have only driven it 40km and it's not even on the road yet... :ban:

It's doesn't scrape on anything, pretty stock height but the car is new to me, no existing damage underneath so I think I am pretty safe there.

Great advice guys, keep it coming.

Luke

munchstagea Mentor

munchstagea

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To add to this, another question: In neutral, slowly bring the revs up to 3k, should I see boost?

I see vacuum, but do get some boost when bringing revs up quickly with a reasonable, not to aggressive stab of the loud pedal...

Luke

munchstagea Mentor

munchstagea

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are you getting any error codes from the consult port (assuming you still have a stock ecu)??

Stock ECU, stock everything as far as I know, have not gone down that path yet.

you will only get boost in neutral if u really punch it. there is no load to bring the boost on.

Really? That's very good to know, so if I "stall it up" I should see boost? Will try that tomorrow.

Cheers

Luke

mad082 Grand Master

mad082

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thats one advantage of turbo's over superchargers. in a manual turbo if you miss a gear and rev it out there is little boost, where-as in a supercharger if you miss a gear the engine still cops full boost. thats why holden never made the supercharged v6's in manual.

Tangles Grand Master

Tangles

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Matey - has the sweet-as Stag got a pod filter (no airbox)? They make 'induction' noise, sort of.....

damn that sucks that you've got a worry so early in Stagea ownership. it'll come good tho, no doubt about it :ban:

munchstagea Mentor

munchstagea

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Matey - has the sweet-as Stag got a pod filter (no airbox)? They make 'induction' noise, sort of.....

damn that sucks that you've got a worry so early in Stagea ownership. it'll come good tho, no doubt about it :P

All stock air box etc.

Yeah I know dramas, will get it sorted, don't have a choice!

Luke

R31Nismoid Grand Master

R31Nismoid

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Hmmm... Have a look at the exhaust from underneath the car... Are there any pipes running off the waste gate/turbo that are cut off and vented atmospherically??? If so, you have a screamer pipe :( that’s the only conclusion i can think of if its an "induction" noise heard at around 5000RPM as that is when the waste gate is fully open... The screamer pipe is a separation of the waste gate housing from the turbo as to vent the boost pressure atmospherically, its meant to help increase top end power however is illegal in Australia... sounds awesome on large turbos... Let us know how you go..

Regards,

Sarkis

Well considering he says it does it in neutral... and a screamer/wastegate wont open in neutral

its fair to say that its got nothing to do with a "screamer" pipe

ICER33 Community Regular

ICER33

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Posted

mate the best place for work on turbo's is Dalton's down on wood st. chris is real helpful and he would screw you around. also geelong tuneups which is on wood st to are supposed to be pretty cluey. (i think one of the guys there racers in some porsche league).

either way there are both off fyans street.

good luck

munchstagea Mentor

munchstagea

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mate the best place for work on turbo's is Dalton's down on wood st. chris is real helpful and he would screw you around. also geelong tuneups which is on wood st to are supposed to be pretty cluey. (i think one of the guys there racers in some porsche league).

either way there are both off fyans street.

good luck

ICER33

Thanks for the info, I will look them up, would be nice to have a trained ear have a listen before I get too carried away...

Cheers

Luke

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