just installed the HKS rs suction kit intake and after doing so i thought it was just me being able to hear the turbo spool much better but its pretty loud and i just want to make sure that its normal and not surging or something.... what does compressor surge sound like? and i dont think im leaking boost or anything i have a hallman mbc and gauge sticks at 20psi all the way up.... thanks for the help!


evoisdream

 

the open element will make the turbo louder. i beleive that if you have compressor surge the car will jerk when you let off the gas.

 

Yes.. It feels like a bit of a stumble.. basically its because the excess boost pressure is resisting the turbo from spinning for a moment and "stopping up" the exhaust until it can vent, in some extreme cases it can reverse the spin of the turbo and potentially damage the shaft or compressor wheel fins.... Sometimes you can hear a bit of a noise, but its not really something that I have "Heard' more like felt..

 

ok right on just making sure that the loud spool was ok its not bad i like the way it sounds it just went from dead silent to totally hearing it spool.. i have a slight stumble if im at high rpm on the highway in 5th and very slowly let off the throttle well in boost... but if i just let it blow off all the way it does it all normal does that sound right?

 

Its gonna take a few days of driving for you and your passengers to get used to the new noised coming from your engine bay. When I first drove my EVO with the HKS RS installed, I was expecting a noise change, but not the sick, airplane like, pissed off noise it makes.

The bov flutter is annoying at times. And yes, it does buck when I get on and off the throttle fast at high rpm's, but time has proved valuable in getting used to a new EVO, again.

 

Yes, if you have no other engine management, its likely compressor surge.. Sometimes if you have a piggyback system, or made adjustments it can also be a transition back to closed loop fuel control.. But what your describing is exactly what a mild compressor surge feels like. I do know it used to happen on my car even when it was stock, you can't eliminate compressor surge completely, you can just minimize it and prevent the damage it can cause by using aftermarket parts and not adequately spending the time to adjust it...

 

what else would need to be adjusted jack i dont have much other then the BOV i could imagine being adjusted but they say not to play with the ssq...

 

Mine had a bit of surge around 50MPH cruising with the stock BOV.

I replaced that with a HKS SSQV a long time ago and was able to adjust the jerkiness out completely.

I bought the SSQV before a kit for the Evo existed. Although the original setting was fine I played with it for months to get the optimum setting it has now.

 

moved to engine tech forum.

 

It takes a little adjustment.. Its set to open at a pretty high spring pressure, if your running a VTA (Vent to atmosphere setup) the car will stall if you lower the pressure (loosten it) to get it to run correctly without surge.. If its recirculated, you can set it up to open alot easier and your surge will go away... IT takes a little while to get "Just right" but its worth the effort..

Your car is pretty stock otherwise, there's not much else to adjust except your idle speed, but thats something that doesn't apply to your situation..

 

so the bolt on the ssq would need to be adjusted out? or in? thanks

 

Out.. I think.. I don't remember at this point because I did it quickly over the weekend.

 

I had a heavy spring in a Tial VTA BOV and got a little surge. There was no noticable performance problem. Under light throttle decel and unloading the BOV was too tight to vent and the air would escape back through the stock turbo. It sounded like a rattlesnake flutter. It was loud from the open intake. I thought the flutter was the BOV, but it was closed tight. I put a lighter spring in and now when it used to rattlesnake flutter I get a nice even woosh. No performance effects either way, but I knew it couldn't be good jamming air backwards through the turbo. That was my understanding of compressor surge but I suppose there are more severe examples.

 

Yes.. For the most part that is what compressor surge is.. but at part throttle you can feel it as a surging.. hence why its called compressor surge..

 

I have the same situation, except I have a greddy type-s bov.

Also on a side note, I hear a wierd sound from my BOV after the "whoosh" sound. It sounds like a door swinging or swing swinging or something. Its kinda hard to explain, but it comes on like a second after the bov does its "whoosh".

Its really annoying, anybody know what it is?