one of the problems i’ve been having with the new motor is the BOV.
i had a Greddy Type S (genuine) on it and i noticed that at idle the bov would leak and cause hunting. as in, it would leak for a minute and the idle would rise, when the idle got high enough it would stop leaking then the idle would drop and the BOv would leak again.
i only had the only straight hose-line fed off the TB. left the diagonal hose line without a line on it as i have always had it and as many people have had it without any problems.
since it was leaking i thought maybe if i tied the diagonal line into a vaccuum source it would hold the bov shut at idle. i know many people have had this problem before and it can cause the car to die on decel if the BOV remains open.
i tied it into the line for hte boost gauge. the BOV stopped leaking.
problem is that it wouldnt open, even under heavy load all i got was compressor surge.
i tried another GReddy Type S that i bought (genuine again) and the same thing happened.
the only way to get them to stop was to tighten the adjuster screw all the way to full hard.
one of our customers has a Type RS bov that i tried, it only has one vaccuum line on it, no diagonal vaccuum line on the RS, and it works better than teh Type S but i still dont think its perfect.
why wont the Type S’s work?
i hate the RS, i cant even tell if its working because the sound (wooosh) is similar to compressor surge, i love the sound of the type S and want to use one of them that i have.
might it just need a stiffer spring? or am i teeing the diagonal line incorrectly?
I’ve had this problem with every BOV I’ve ever run. Granted that’s only been a couple but …
What happens is once the BOV vents, there is enough vacuum in the system to keep it open. You need to introduce positive pressure to get to shut completely (give it a rev)
With the PIT Type H (hey, it’s never leaked and holds fine to 17psi)
I just had to play with shims and adjustment.
The only way I could get it to stop leaking was to accept a bit of low throttle compressor surge.
Too tight it wouldn’t open, too loose, it would leak.
A bit of surge isn’t a bad thing. Surging off load is much different than surging under load.
I think to use that other vacuum line, you need some kind of a check valve on it. I could be remembering something else though
Weird… I can loosen off my BOV fully and it wont leak and does not get stuck open at all, or can I can tighten fully and it doesnt change anything, lol.
I get slight compressor surge around 3000rpm as the Turbo is just spooling then but by the time its fully boosted around 3700rpm it will blow off. But no matter how loose or tight the BOV is, it still blows off @ the same times.
Leading me to think the damn Blitz Spring is just way to friggin stiff
I would never buy a Greddy because I dont trust the Diaphram System vs the Piston/Spring setup but I do like the fact that they’ll actually blow off @ a lower RPM but they also tend to leak/stick open which leaves me thinking I may try an HKS Unit
