anti-surge compressor housing

[mach4g63t]

Okay, so I got a SBR G60 with the big 4" anti-surge compressor housing.

Basically, I've heard of some of the big time turbo users (80mm turbos and such) not using BOV's because their turbos have antisurge housings. What is the relevance of this? Is it because they're just not seeing boost on a frequent basis as someone who would DD their car, but instead only uses it for a few "go big or go home shifts" down the track and then park it until the next pass....?

Does the housing eliminate the need for a BOV, or just help diminish the negative effects of Compressor surge in the event that it happens? Can anyone clarify this for me?

Thanks.

 

[dsm-onster]

Who in hell told you that???

The BOV helps transient responce (re-establishing boost after shifting).

 

[T9S1i]

Well some people us NLTS when they race and that helps keep the turbo spooled, you never hear the BOV when you do that. I wouldnt recommend to NOT have a BOV on the car, just use NLTS when you race to help hold boost inbetween shifts

 

[turboglenn]

I've seen a lot of GN guys that don't run BOV's but one of them broke a compressor wheel off at the shaft shutting down at norwalk about 10 years ago when i was always going to the drag events. I wouldn't risk not running one, for something that's not an all out drag car or something where your trying to shed grams to be competitive it's really notworth the risk of damage in my opinion. I am pretty sure the anti-surge housings are only to combat surging under high boost at partial (say 75%) load or something like that where surging under boost tends to take place. I would not even think of making it have to deal with slamming the throttle plate shut all at once.

 

[trick engine]

The Anti surge Housing allows compressed air coming out of the turbo to recirculate back into the inlet to prevent compresor surge .
Basically with a large turbo your engine can only consume a given amount of air at lower revs if the turbo is flowing more then this amount it causes compressor surge . which is air flowing backwards into the compressor wheel . Which is real bad for the turbo.

My old T66 without the surge cover did this really bad .
My new GT42R has the anti surge and it works awesome no surge at all .

 

[dsm-onster]

^^Yes.

Running no bov/bypass valve will cause surge because you engine suddenly accepts less air volume during a lift in throttle. The air loads up onto the butterfly and reflects back down the charge pipe speeding towards the compressor wheel. The problem with not running a BOV/bypass valve even with an anti-surge compressor cover is that the air causing the surge during a throttle snap is already past the antisurge ports and has to go back into the compressor wheel to reach the ports again. This is surge.

The fact that an anti-surge (MWE) port recirculates the air coming in is effective at preventing too much air entering the charge pipe in the first place. But, releasing the accelerator pedal after a WOT pull causes there to be "too much air" for the demand regardless of any size turbo or any style cover.

The bov/bypass valve also allows the compressor to 'free wheel' between shifts when you lift, instead of accepting negative work from the aircharge that would otherwise slow it down. So transient response is better.

 

[mach4g63t]

So, another question about Compressor Covers...

I have the slowboy G60... you can get this in a standard model (I believe the T04e cover) and then you can opt for a larger compressor cover (t04s). Are there any real benefits to having this cover in terms of how the turbine will perform in the top ranges of its power? Will it allow the turbo to flow more air? Does the change in compressor covers require a change in compressor wheels also?

Thanks!