turbo whine with intercooler on 1994 1.9td

[cluelessgoon]

Hello all,

  I recently added an intercooler to my 1994 1.9 td audi 80.  Previously the performance was awful (0-60 in 16 seconds!), by adding an intercooler from a 2.5 diesel landrover and refueling, I got that down to 12s - no smoke, boosting to about 13psi.  The PROBLEM is the incredible turbo whine - which can be heard hundreds of feet away.  This is really noticable to the driver and very annoying after a while.  The problem is worse when driving at a constant speed, say 30mph, when the turbo comes on and off boost all the time.  Once revving at above 2200 the whine cannot be heard as the turbo is spinning fully.  The whine appears to be due to the low spinning speed of the turbo.

  We have tried other intercoolers - which yielded the same result.  Ducting to and from the intercooler is a combination of welded aluminium triangle section and silicone hosing.  

  Running without the intercooler (as I am doing now) is great - lovely low-down torque and the turbo is utterly silent.  You can just hear it spinning up about 1300 rpm!  However the power is just not as good higher up.

  This leads me to think that the resistance offered by the intercooler was too high for my current turbo.  Do regulars here think I could improve this  situation by...

1) fitting a smaller, fast flow intercooler - offering lower resistance
2) fitting a bigger turbo - if so which one?

  Other mods we are considering are...
1) new exhaust
2) gas-flowing the head as we hear the machine is awful inside
3) injector upgrade (no-idea which ones, or whether we can burn any more diesel!)

Cheers

[QuickTD]

Are you sure it isn't the piping causing the noise? Corrugated hose of any kind can produce very loud noises at certain airflow rates. I once thought that water pump hose would work on my shop vacuum cleaner, sounded like an air raid siren...

[DieselMonkey]

Sounds like a leak in the pipework or intercooler.

Turbos are quite reliable, unlikely there is anything wrong with it. If in doubt, remove the intake pipe and check the shaft for play from side to side, not up and down movement. All turbos that I can think of, used on VAG motors, have a floating bearing structure, so they will have play up and down, but not side to side. Still, doesnt sound like its the turbo.

DM

[cluelessgoon]

QuickTD

   It could be the ducting.  The aluminium triangle sections form the bulk of the distance covered and are about 60cm long.  They are trianglular to allow us to squeeze both the supply and return to the IC through a smallish gap behind the radiator (together they form a square).  The noise is consistant until the revs get up - it's no louder or quieter at any point.

  I could reconnect them, and just replace the IC with a straight thru section as a test.

  I feel that with the increased fuelling I am running an intercooler is benificial for engine longevity, so I'd quite like use it if I can.  There's also the performance too!

  Cheers for the suggestion.

[cluelessgoon]

I should mention that this is the second turbo (brand new) I've used on the car.  The first one boosted irregularly and once we added the intercooler it failed spectacularly.  This was an expensive repair!

The noise was exactly the same on both the old (knackered) turbo and new turbo, pointing more to the IC setup.  

You guys are probably right with the pipework suggestion.  The fact that it is welded aluminium section means there could easily be a hole, or that the noise is amplified in some way.  This is good as I don't want to replace the turbo again or fit a giant-engine-destroying turbo really.

cheers

[DieselMonkey]

What turbo and engine are we discussing ?

1.9TD w/K03 ??

DM

[cluelessgoon]

yep - brand new k03-003.  Undetectable without the IC (well a tiny bit just above idle), but with the IC  the noise starts with a frequency humans can whistle at and then progresses up to undetectable as long as acceleration is maintained.

It attracts the wong kind of attention, so I took it off.

[zyewdall]

Some people would pay good money to acquire the noise that you are trying to get rid of:

Geeez.  And I thought it was bad that people actually pay to get the sound that my old subaru has after I drive up a jeep trail and accidentally tear the exhaust system off on the rocks.....

[cluelessgoon]

 

Oh yeah - first of all I was delighted with the sound, but after a day or too it became really loud and annoying.  People turn around to look at me.  It's not normal.  The noisiest turbos I hear over here in the UK are Peugeot/Citroens and this was way louder.  Also the noise is quite low frequency - not like a high pitched whine, so people don't think it's a turbo!

[DieselMonkey]

I dont know why Pug's and Citreons seem to make more noise than VAG IDI's, they mostly use a K03 also, it is a very quiet turbo. Thats why I like Garretts, but the K03 is very reliable.

I've found any VAG DI motor, esp. the VNT turboed engines, sound real nice, Mercedes CDi's too.

The intake pipe came off my mk2 GTD w/1.9 AAZ one day, it had a Garrett GT15. I had to drive it home with no intake pipe, and when making boost it sounded excellent,....that cars sold now but I fitted a new GT15 to my Mk3 project probably because of that drive home !!! I was grinning from ear to ear.  :lol:

The noise produced by the compressor wheel is actually a design fault. I work with a former employee of Holset turbo; he asked me one day why there was a VW manifold and K03 turbo sitting on my tool box. He'd only started the week before so it was a good ice breaker. Turns out hes quite knowledgeable about the Cummins B series 5.9L... Holset are of course owned by Cummins. He'd worked as project manager on projects related to the HX series for the Cummins engines, and left just as Holset had started work on VNT turbos. Very smart chap, and to cut the story short, explained that Holset, and all turbo manufacturers, are constantly trying to make there turbo's quieter, becuase the whistle is the signature of a compressor housing that isnt optimally designed. If I remember right, it occurs because the compressor wheel can no longer draw air, compress it and discharge it efficiently at certian speeds because of its design.

When I got my new GT15, he was looking at it while I rotated the housings and bearing cartridge so it would suit a mk3 Golf rather than a Audi A3, he asked why I wasnt using the K03, I said becuase I got the GT15 brand new and at a very good price, and more important, it makes a lot more noise. He said quite simply, So its a very ineffiecient little thing then ! Thats when he explained why they whistle, unfortunatly I cant remember all the information he gave me about it though.

Still used the GT15 of course ! always learn the hard way ! :lol:

The sound my Mk2 GTD was making wasnt hard to put up with, your problem must be a leak in the pipework or the intercooler itself.

Hope this helps, DM

[jtanguay]

Some people would pay good money to acquire the noise that you are trying to get rid of:

hahahahahahaha