Compressor surge?

[lars y]

Hi,
I`m not sure if this is compressor surge or what, but when i was cruising in 5th on the highway and stepped on the throttle to accelerate the boost went up to about 20psi and while i was at WOT it sounded like my bov was opening and closing fast and the boost gauge needle was jumping from 10 to 20 psi rapidly.
This also happened in 4th when i was going up a hill.

I have a Tial 50mm Q bov and a GT3076r with a T31 exhaust housing externally gated with a Tial F41. I`m running speed density.

The bov is directly connected to the intake manifold.

Is this compressor surge? And what can i do to fix it?

Thank you

 

[donniekak]

Sounds like compressor surge. A larger turbine housing can help.

 

[lars y]

Yeah, thats what i thought.

But what about using an electronic boost controller? To keep the exhaust partially bypassed at those loads.

Edit: Is this the kind of compressor surge that kills turbos?

Thanks

 

[n0de]

The BOV is directly connected to the intake manifold? Can we get a picture of your engine bay on here?

 

[donniekak]

Yeah, thats what i thought.

But what about using an electronic boost controller? To keep the exhaust partially bypassed at those loads.

Edit: Is this the kind of compressor surge that kills turbos?

Thanks

That depends on if your waste gate spring will open at a pressure lower than the pressure the surge occurs at.

 

[blkgst97]

I believe he means via vacuum line not as in attached.

 

[phr0st]

Which spring/combo is in the F41?

 

[lars y]

Yea the vacuum line is connected to the intake manifold, no T`ing.

The spring in the wastegate is rated at .9 Bar.

I did a bit of searching and found this: http://www.himni-racing.com/turbochargers/garrett-turbine-housings/t3-3.00-v-band-turbine-housing-gt3071r-gt3076r-gt3082r
Is that the bigger turbine housing i need then? Have i understood it correct that i should select a larger A\R housing? Like a 1.06 A\R? I think the one i have now is only a .63 A\R, and only 2.5" outlet.

Thank you

 

[donniekak]

If the problem is only in 5th gear, I would just avoid going high throttle under a certain rpm. If it surges doing pulls in 3rd, and 4th I would do something. Going with the bigger housing may create a lot more lag, to fix something that only happens under very specific circumstances.
Go out and do a pull in 3rd starting at 2500 Rpms, wot. If no surge occurs I'd just drive around it on the highway.

 

[lars y]

Yeah i agree. I haven`t done any real pulls yet as i`m still breaking in the engine.
So the thing with compressor surge is basically the engine can`t consume all the air the turbo is pushing? But if i`m going higher rpm it should be able to? I think the surge happened around 4000 rpm.

Thanks

 

[donniekak]

In simplest terms. A turbo compressor has to flow a certain amount of air at a certain boost level. If there is to much boost at a given flow, surge results.

 

[lars y]

I see thank you.

Should i be able to pull out 4th gear if i start boosting in a higher rpm?
Is the surge only going to be at lower rpm`s and disappear when i rev the engine enough up so that it can flow enough air for the boost?
I haven`t encountered surge in 3rd although i haven`t pulled further than to around 5-6000 rpm`s.