Dash Rendar Posted October 16, 2007 Share Posted October 16, 2007 The other day I was fortunate enough to be sat in the passenger seat of a T61 Supra. However, at full (sustained) boost there was a repetetive 'clacking' sound. Imagine hitting steel venetian blinds with a ruler at a rate of about 3 times per second... Only *much* louder. That's what it sounded like. This wasn't apparent until full boost was achieved and sustained. I've been in big-singles before, and only ever heard the mighty 'whoosh' of air. I've never heard a turbo make a sound like this. It was almost as if pockets of air were slamming into something in the system at regular intervals. The owner didn't know what could cause this. I was wondering if anyone has any ideas? Quote Link to comment Share on other sites More sharing options...
Matt Harwood Posted October 17, 2007 Share Posted October 17, 2007 Did it sould a bit like a few small screws rattling around in a tin? - If so, that sounds worryingly like detonation - Too weak AFR possibly? If was a fairly quiet repetative clicking coming from an auto gearbox, that has something to do with solenoids, but I can't elaborate any more than that. Quote Link to comment Share on other sites More sharing options...
Dash Rendar Posted October 17, 2007 Author Share Posted October 17, 2007 Screws rattling in a tin... maybe. But it was fairly regular and rather loud. Quote Link to comment Share on other sites More sharing options...
Dash Rendar Posted October 17, 2007 Author Share Posted October 17, 2007 I guess soundbytes of det are hard to come by! Quote Link to comment Share on other sites More sharing options...
Mike B Posted October 17, 2007 Share Posted October 17, 2007 you are sure it wasn't the wastegate? some are noisy. Quote Link to comment Share on other sites More sharing options...
Matt Harwood Posted October 17, 2007 Share Posted October 17, 2007 I wouldn't want to try to record it! Does the car have an AFR gauge? - If not, I'd suggest getting to the nearest rollong road, (off boost), as quick as possible, just to make sure that isnt what's happening. - If it is det, it's just a matter of time... Quote Link to comment Share on other sites More sharing options...
Dash Rendar Posted October 17, 2007 Author Share Posted October 17, 2007 It did have an AFR, but I didn't really get any chance to pay attention. So what does a loud wastegate sound like? I thought that would be more like a BOV kind of noise... Only louder. The owner of the car didn't seem too concerned with the noise, but I was just curious. Cheers all. Quote Link to comment Share on other sites More sharing options...
Homer Posted October 17, 2007 Share Posted October 17, 2007 I'm not sure what you mean Mike, the wastegate itself shouldn't make any noise, it's just a big valve thats either open or closed (or at some stage in between the two ). Are you referring to the noise from the exit? The exhaust gases passing through a wastegate are often directed to atmosphere rather than routed back to the exhaust. The pipe is commonly called a screamer pipe - and for a good reason! When the car reaches target boost all excess exhaust gases are directed out of the wastegate, down a short tube and out under the engine bay. These make an enormous amount of noise when the car is on full boost, it's basically an unsilenced exhaust pipe only 2 foot (or so) from the cylinder hence the name. However, it's just a constant 'scream' sound, there should be no oscillation of other noise coming from it. There's something else going on there to cause the noise... Quote Link to comment Share on other sites More sharing options...
Mike B Posted October 18, 2007 Share Posted October 18, 2007 I'm not sure what you mean Mike, the wastegate itself shouldn't make any noise, it's just a big valve thats either open or closed (or at some stage in between the two ). Are you referring to the noise from the exit? I have heard it in a number of singles. Granted when the screamer pipe is open then the noise is so loud that if you can hear anything else you are doing well! When I plummed my screamer back into the exhaust to shut it up you can hear the external wastegate operate. I'd best describe it as a chattering.. lots of small irregular pressure releases that sounds quite unusual. It's not very loud but it's noticable. At least i hope it's that , no, just kidding; I'm 100% certain it is.. I have heard it in Michel's car too, and you can hear the same frequency of the noise, all be it at a greater volume in an open screamer pipe. Quote Link to comment Share on other sites More sharing options...
Matt Harwood Posted October 18, 2007 Share Posted October 18, 2007 You should only hear that noise on lift off really, unless something is wrong elsewhere... Quote Link to comment Share on other sites More sharing options...
Guest For-Tune PVE Posted October 18, 2007 Share Posted October 18, 2007 There's a chance it may be a boost control solenoid/BCV/AMAL valve, whatever you may know it as. Quote Link to comment Share on other sites More sharing options...
Dash Rendar Posted October 20, 2007 Author Share Posted October 20, 2007 So Mike, if I'm understanding you right, the wastegate can open regularly at short intervals, to vent off excess boost in pockets? I guess if that sound was essentially being 'amplified' through the screamer pipe, it might explain it. Dunno... Matt, why would you only hear this wastegate noise on lift-off? I thought the wastegate was venting the excess pressure, and that this would happen under full boost? Or is it because the wastegate should only close on lift-off, and that's the only sound you should hear? (This demonstrates my lack of knowledge regarding how a wastegate operates!) Quote Link to comment Share on other sites More sharing options...
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