Morfeus17

Not sure on this one?? I could be driving while in vacumm or close to about 1 psi and once I deccelerate this surging sound would be heard. A friend of mine indicated to me that this surging sound is called "Compressor Surge". Not sure if I agree...

After all this time hearing this, I thought the blow-off valve was behind the surging noise. I assume this because it's set to fully soft. He then advised me to tighten the BOV.. I tried the same experiment again and still heard this surging noise.. So perhaps he's right..

My question now is,, explain to me this "Compression Surge" Phenomenon.. Is it Good, Bad, or Ugly??? And Can I rectify it...

Thanks.

I30tMikeD

iTrader: (8)

Compressor surge is when charged air hits a closed thottle plate and bounces back to the turbo. It is bad for the turbo. That is the point of a blow off valve, to release the air so it does not travel back to the compressor.

I have only heard compressor surge a couple times in my brothers car...I had a hard time telling the difference between the BOV and compressor surge.

superdave2

LOL - you're learning and you aren't even turbo (yet)! Ready for FI?

superdave2

Oh, if you are getting compressor sure, you need to LOOSEN your BOV, not tighten it.

Stephen Max

iTrader: (59)

In some cases you have to go to a larger blow off valve. I had a serious surge problem when I rerouted my intake piping which resulted in a larger volume of compressed air that would surge back to the blower whenever I let off the throttle. I loosened my Blitz DD as much as it allowed, which wasn't enough. I put in a softer spring, but that wasn't enough either. Going to a Vortech mondo bov (largest bov known to man!) solved that problem.

Surging is more prevalent with a supercharger since the blower is pumping air no matter what the throttle setting, unlike a turbo system that depends on the volume of exhaust gases to drive the compressor.

Morfeus17

Ok, I see.. Thats very interesting. Well Thanks for the info guys. Looks like I need to find a better BOV.. I will look into that Vortech mondo bov stephen.. Again thanks for the heads-up..

IceY2K1

iTrader: (3)

Is it bigger then a 50mm Tial BOV?

Can the mondo be rerouted to recirc?

MAXimumHP

iTrader: (7)

I have the Blitz as well, and it seems to me that I have to loosen the BOV so much to keep the Surge down, that it can't hold the boost then. I swapped to a softer spring too, but was loosing boost, so back to the stiffer one for me. I hate that sound too.

Morfeus17

Just as a heads up.. I sawpped out my Greddy Type S BOV for an HKS Race BOV. And sure enough, my compressor surge is eliminated. When you compare the Two BOV's, the greddy type s is a lot smaller machanically.. The inner piston travel, Piston diameter, and chamber size is noticably reduced. While the HKS Race BOV has a greater piston travel, diameter size and chamber.

Boost response and power is noticably improved. The car pulls harder and the turbo is a lot more responsive under accleration between shifts. I guess the greddy unit can't handle boost response when it comes to Six cyclinder motors under FI. So the the old unit must of been loosing boost under these conditions.

Its hard to believe that something like a incorrect BOV can affect performance in this manner. Not all BOV's are the same.

Otherwise thanks for the info and help.

Stephen Max

iTrader: (59)

The Mondo has a 2 inch ID flange, that would be 50.8 mm. So, yeah, it's bigger.

You can fit a 2" hose to the bov outlet for recirc.

MAXimumHP

iTrader: (7)

Interesting info. Maybe I should be looking at a new BOV

matty

iTrader: (54)

Is it possible to get a great amout of compressor surge with a s/c w/Greddy Type S ?? I am gettin a lot of whooshing noise lets say between 1st and 2nd shifts or if im in 3rd and give it a shot....

The noise is exactly explained like if Im at idle and i put my hand over the outlet of the Greddy, and rev the car up..and the air rushes back threw the blower..thats the noise im hearing.

I took apart the Greddy today and cleaned it/greased it and its working 10X better...it blows alot more air out..

guys with the greddy/S/C hear this same noise ?? Compressor surge ??

-matt

vortechpower

iTrader: (1)

I hear the same noise with the blitz(wooosh). I dont think that some compressor surge is really bad for a s/c. The reversed flow of air is not affecting the speed of the impeller since it is driven by the motor with belt. I try to minimize this by adjusting the bov to release air just as the rpms begin to decrease. I match that up at about 2800 rpm. Just a method I figured out over time.

vortechpower

iTrader: (1)

I tried the hks ssq and got serious comp surge. I dont think hks go well with the max s/c set up. I have always wanted to know if there is any strict guidlines on adjusting the b0v

matty

iTrader: (54)

Well its a shame Greddy doesnt sell the top housing of there BOV seperate...they only sell the entire BOV as a unit.

I bought this BOV and the top set bolt was stripped out and Ruined..they had a jery-rigged allen set screw in the top...its not leaking and still applys pressure on the spring so dont think thats my problem....its just really hard to adjust...right now I have it srewed right near the top so its just sealing the hole, and just starting to apply pressure...
See top of pic


That whoosing sound I hear, going back threw the blower is ok...its a really deap sounding Whoooshh..

-matt

vortechpower

iTrader: (1)

Sounds unique, just buy your self a screw that you can turn by hand. Thats what I did

Morfeus17

Not sure on how compressor surge sounds with S/C.. But from my observations, while T/C the surging noise almost sounds like a turkey, but with less gobble.. Very distinc when decceleration occurs.

vortechpower

iTrader: (1)

like a flutter sound?

matty

iTrader: (54)

I thaught compressor surge is a Whoosh sound...a constant deep growling noise ??? (take your hand and cover your BOV, Rev up your car and youll hear what surge sounds like)

The flutter noise is the BOV working as the air passes by the diaphram and out into atmosphere...

-matt

vortechpower

iTrader: (1)

Its a woosh sound for us, s/c at non boosted speeds. I know ever since I put on the cold air intake I get a flutter sound from it when shifting from red line when the bov is set right/tight

Morfeus17

Yes.. The sound it gives is fluttering.