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Trumpet Sounding Air Leak When Turbo Spools Up, Can't Find Where?

Rolls

By Rolls,
in Engines & Forced Induction

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Rolls Grand Master

Rolls

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Posted (edited)

So I finished my engine swap about a month ago (25 neo in a 32) and sent it off to boostworx to get a few minor things fixed up new metal intake, getting some broken studs and stuff I cbfd doing myself fixed.

Now everything was finished up last week and the car seemed great the first 5 minutes then I noticed that on 18psi when the turbo spools up whether you flatten it from 2k or rev it out slowly and then plant it at 5k it makes this flapping trumpet noise as it spools to full boost, the noise goes away after full boost has been achieved though. So if you drive it flat from 2k it happens around 3-4k then goes away, or if you rev it to say 5k and plant it it happens around 5.5-6k then goes away.

I thought possibly at peak torque the engine was cocking over and slightly causing a gasket or intercooler pipe to leak however we have pressure tested the entire system and have not found the leak, it also doesn't really happen on the dyno only on the road so we can't find it when sticking our heads in the engine bay.

The noise is an extremely loud trumpet flappy noise, being as it only happens on the road it is proving very difficult to diagnose. Apart from pulling the intake manifold off and redoing the intake gasket (I had to swap it during my coversion) I'm not sure where else to look, rather not do this as its a huge pain in the ass and might not be the issue.

Aside from replacing the clamps on the silicon intercooler joiners what other gaskets etc should I be looking at? We have already had the AAC gasket replaced and replaced the studs for the TB as they were leaking as well. Sounds like it is coming from the bottom right of the car when driving, but that could just be because of where the driver window is. AFRs are fine and the car doesn't run rich so there is a possibility it isn't a leak and something entirely different.

Any ideas be much appreciated.

Edited by Rolls
Rolls Grand Master

Rolls

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Posted (edited)

from memory this could be the stock intake pipe sucking shut

do you have the std item still

Nope just had it replaced with a metal item, car doesn't loose any power either when it happens, drives fine just the noise sounds horrible.

Edited by Rolls
Lithium Grand Master

Lithium

Posted
Posted

Do you use a MAP sensor or AFM? If AFM, odds are it'd be running rich if thats the case. Exhaust leaks in my experience tend to be way noisier, and leaks on the manifold side tend to be harsher (almost a mechanical scream) - on the dump pipe side tend to be a bit more of a weird noise which could be described as trumpety.

These are just observations based on my point of view when I've seen these things, could be wrong - but exhaust leaks are usually pretty easy to spot as there will be discolouration from where the gas has been escaping.

Rolls Grand Master

Rolls

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Highflowed rb20 turbo, it isn't compressor surge as I know what that sounds like and it is nothing like this, I have also run this turbo on an rb25 before without issues.

Stock recirc bov, eboost street.

chiksluvit Experienced

chiksluvit

Posted
Posted

had the same problem, intercooler pipe hose joiner wasn't tightened properly at the IC exit

it looked fine but opens up slightly when its pressurised (on boost)

readjusted the angle and tightened the clamp, and the noise never came back again

GTScotT Grand Master

GTScotT

Posted
Posted

Have had this myself.. Its the gasket between the turbo and manifold. You either reused a warped gasket or its not on tight.

Hand in hand with no notable power loss.

Rolls Grand Master

Rolls

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Have had this myself.. Its the gasket between the turbo and manifold. You either reused a warped gasket or its not on tight.

Hand in hand with no notable power loss.

I completely forgot I snapped a stud when putting it on, almost certainly that, I'll give them a buzz tomorrow.

Rolls Grand Master

Rolls

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bolts between the manifold to the turbo are lose or gasket is gone :)

Getting him to have a look and replace the stud/gasket first as the inlet manifold is a flamin mongrel to do and $$

I could do it but itd be a day Id take off work without pay, might as well just get him to do it. Oh wells such is cars $$$$$

Rolls Grand Master

Rolls

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geez Rolls rookie mistake , only reason I didnt mention it was cause I thought you would of thought of it already.

Mine did it too somehow turbo bolts had just rattled loose...

Just completely forgot about it, I'm not 100% it has snapped it just seemed to free spin a bit when i had finished tightening it so I just left it in case it had snapped, that was like 2 months ago though so completely slipped my mind.

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