Harsh Induction Noise At Around 5,000rpm

[munchstagea]

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

[SoFly]

would this be like a screaming sound?

[munchstagea]

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]

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

[bloodsword27]

screamer aye?! :| ahaha...i wouldnt mind a screamer pipe either hahah finkn of droping 1jgte in2 my dads hiace hahaha

[stolen_s15]

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 May 6, 2006 by stolen_s15

[munchstagea]

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...

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]

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

[ian]

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

[mad082]

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

[munchstagea]

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]

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]

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

[munchstagea]

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

All stock air box etc.

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

Luke

[ardie]

check ur gaskets, ong of my friends had a similar problem and it was that one of his gaskets had deteriated over time and when a bit of pressure went you would hear a high pitched squeal/scream

[R31Nismoid]

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]

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]

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

[paulr33]

try repeating same thing with the stock airfilter panel removed

[munchstagea]

try repeating same thing with the stock airfilter panel removed

...and what should I get then?