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True Compressor Surge, Info/Elimination

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98gst14b

15+ Year Contributor
453
0
Jan 24, 2006
Keys, Florida
After going through some problems with two prior turbos (story in link below.) I ended up working with jusmx and he put together a Kinetic G60 T04E compressor with my old .63 garret t3 housing. I installed the turbo and ended up getting compressor surge from around 21-25 psi, depending on which gear the WOT is done on, the quicker the spool, the worse the surge was. It "seems" mild the boost gauge does not fluctuate and the performance is not affected/no hesitation or "bucking." Also I read that this can eventually destroy the bearings so I wanted to figure this out. Can someone explain exactly whats happening? I have never had experience with this before, and is there anything I can do to combat this issue? Maybe bigger charge pipes? intake/exhaust modifications? Thanks for your advice :thumb:

http://www.dsmtuners.com/forums/turbo-system-tech/330461-my-turbo-going-video.html
 
maybe a to4s? Upgrading the exhaust housing would suck I would have to re-do a lot of stuff.
 
gotcha, so the turbo is pushing more air than the engine can handle.
 
What I will probably end up doing is keeping the boost low till I get some $$ together for 272's
 
TurboByGarrett.com - FAQ's

What is compressor surge?

The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side.

Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself.

Common conditions that result in compressor surge on turbocharger gasoline engines are:

- A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body
- The outlet plumbing for the bypass valve is too small or restrictive
- The turbo is too big for the application.



I agree with others- there has to be too much intake restriction once you reach a certain boost level. Cams may help, large intercooler piping may help....especially if you're using a 2G throttle body elbow on your car. Most guys don't realize that a 2G throttle body elbow is only 52mm (just over 2") the entire inside diameter, which is smaller than a 1G throttle body.
 
Like has been said before your turbo is flowing too much air for the engine to ingest at your operating points. If you have surge at WOT you need to increase the amount of air your engine can flow with a certain displacement and engine speed, aka increase your volumetric efficiency/eliminate flow restrictions post compressor outlet.

You could reduce boost (yeah, shitty option) or try to find a compressor cover with a ported shroud depending on how bad your surge problem is. Also, maybe look into a better turbo match for your application if none of these other options are viable.

Bill
 
Stroker motor or turbo that flows less air/spools slower at lower rpms.
 
A cheap option may be trying to use a smaller compressor until you make the engine flow more air. You can grenade the compressor wheel from surging. Cams will help flow much more air but may not solve the issue completly. You should try to find a compressor map for your wheel and see what airflow it supports and compare to actual airflow.
 
Like has been said before your turbo is flowing too much air for the engine to ingest at your operating points. If you have surge at WOT you need to increase the amount of air your engine can flow with a certain displacement and engine speed, aka increase your volumetric efficiency/eliminate flow restrictions post compressor outlet.

You could reduce boost (yeah, shitty option) or try to find a compressor cover with a ported shroud depending on how bad your surge problem is. Also, maybe look into a better turbo match for your application if none of these other options are viable.

Bill

:thumb: Great post, Bill.

A cheap option may be trying to use a smaller compressor until you make the engine flow more air. You can grenade the compressor wheel from surging. Cams will help flow much more air but may not solve the issue completly. You should try to find a compressor map for your wheel and see what airflow it supports and compare to actual airflow.

I'm not sure why one would go through all the work of changing compressors; all he needs to do is lower the boost or not go WOT until he has the money to fix this.

There is no sense in buying a different compressor side to combat a problem that can be fixed by a change in driving habits :hmm:

On a related note, have you logged lb/min or any airflow data?
 
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