blow off valves

[samlloyd]

Just got a question in relation to bovs.

My car was on the dyno on friday, after getting a few things done to the motor (rb30det). The tuner says its getting heaps of compressor surge. Its a small turbo for the size of the motor; a T3/T4 .63exhaust (thats all i know at this stage )

Its got a genuine blitz sequential job on it at the moment. My tuner reckoned to run a standard type bov aswell as the one thats on there. Does anyone else do this. Would this just be because the standard ones have a lighter spring in them or something? How would a standard one be more efficient? And can i use any type of standard turbo vehicles bov?


Also having troubles with the internal wastegate not holding boost, i think the spring in it is just not quality enough. Currently 160kw at 3800rpm, then boost starts getting out of control there.

Car is still on dyno, will be on it all tomorrow.

[IH8TEC]

if your car does not have that good a vaccuum (like my car) then yeah a lighter spring helps, my bov's are slightly open at idle, but on throttle close up good. i beleive it can be a problem however if it's afm. not sure what your one is?

can you adjust your blitz one? do you run the line straight from the intake manifold? on it's own line.

and what form of boost control are you using? just the spring?

[samlloyd]

Its just had a link G3 installed, so no afm anymore. Boost control done by computer/wastegate. I think there is a Allen key type screw on the top, maybe ill try loosening it off?

I dont think it is on its own line but will check, (was installed before i bought car)

[Crucible]

The tuner says its getting heaps of compressor surge. Its a small turbo for the size of the motor; a T3/T4 .63exhaust (thats all i know at this stage )

Its got a genuine blitz sequential job on it at the moment. My tuner reckoned to run a standard type bov aswell as the one thats on there. Does anyone else do this. Would this just be because the standard ones have a lighter spring in them or something? How would a standard one be more efficient? And can i use any type of standard turbo vehicles bov?

ssq copies and genuine HKS ssq bovs dont vent very well....if any at all!. I had one on my car and got rid of it because it was surging quite bad. Others i know have had the same problem aswell.

[samlloyd]

Mines more like this, without the trumpet extension



Its not like this,




If i find another bov ill try swapping it and see if that helps

[Dell'Orto]

Might be that the Blitz one just can't dump enough air, they've got quite a small piston so that could be the issue.

[AJz]

ssq copies and genuine HKS ssq bovs dont vent very well....if any at all!. I had one on my car and got rid of it because it was surging quite bad. Others i know have had the same problem aswell.

Interesting you say that. Quite a few people recommend them as being one of the top because of the way they work. Baring in mind the genuine HKS would be of higher quality compared to the "no name" SSQV ones.

I used to run one i bought off Al @ Driven. Worked fine for me with standard boost. I got rid of it cos the noise drove me nuts after a while. Back to the factory one atm.

[Bumpy]

I have a genuine hks ssqv on my starlet, and those copies are S$%T!

I have never had any probs with mine and I've pulled it apart a couple of times over the 5 years i've had it to have a tootuu.

The only reason you'll be getting compressor surge is because the blow off valve isnt opening up enough, just find another vacuum source or get another blow off valve ...

[tsoob]

i have the same blitz one on mine it is going on the dyno tomorrow arvo so will see if i have the same probs or not.

[samlloyd]

Mines off the dyno and im picking it up today. The internal wastegate isnt working so well so boost does spike. The remedied it a bit and got the boost curve a bit flatter. But it really does need boring/external.

180rwkw at 4k though

[TRD_ZERO]

OK maybe its just my run of bad luck but ive had two of those blits ones they are the super sound version......they used to open up hecticly on idle and gave me bad leaks( you really notice it when you run afm). so i replaced it with a rebuilt one and it just jammed open. Thats two of the exact same bov........ so i went all out and paid top$$ for a new genuine hks ssqv as in the bottom pic and had no issues, that design is great i can definatly reccomend them.

[tsoob]

it makes a little surge now was unsure its only if you take your foot off the gas slowly on boost but if you takt it off fast no probs.

Any luck with yours?

[samlloyd]

I havnt had much of a play with it. I got the internal wastegate bored out by roughly 9mm. I can hear the turbo chatter if you rev it up in neutral, with no load on the engine, but im not sure if it does it when it has some load on it and the b.o.v is actually venting.

[escortman]

do u have it set to hard? i played round wit mine 2day seems to be better now, had it set to hard

[evil_si]

who was your tuner? jason at infomotive?

[samlloyd]

yes

[cat007]

What position is best for a BOV? Should it just be T'd into the pipe like this





Or should the BOV pipe be like a Y like this





That way the shock way bounces back INTO the BOV - but the air leaving the turbo has to do a 180degree turn to exit through the BOV
Or should the BOV be facing the other way, so the air leaving the turbo can go straight out the BOV
OR - does it not matter?

What are everyone's thoughts?

[touge rolla]

I don't think it matters. Either way it's easier for air to flow through your bov than backwards through the turbo.

[samlloyd]

It doesnt really matter how the b.o.v is mounted, the rate at which pressure waves move is pretty quick.


just confirming this is my b.o.v

Do i want the top screw adjusted quite far in?

[tsoob]

if you screw it in it goes harder, mine is the same one