how to tune the bov

i have the greddy type s bov that i got from a friend. It didnt have any instructions with it or anything when i got it, and i really only have a basic knowledge of how they work.

Since ive been on these forums, ive noticed some people talk about "tuning their bov". (for example, the "boss called my car a pos" thread, he mentions he took his car to the track to tune the bov.). my question is this... how do you tune it? and also, how does turning the SOFT-HARD knob on the unit affect the performance or how it works? I searched the forums, but didnt find any answers, and i read the one bov sticky but that only explains how a bov in general works. if anyone knows, please help :-)

i have the greddy type s bov that i got from a friend. It didnt have any instructions with it or anything when i got it, and i really only have a basic knowledge of how they work.

Since ive been on these forums, ive noticed some people talk about "tuning their bov". (for example, the "boss called my car a pos" thread, he mentions he took his car to the track to tune the bov.). my question is this... how do you tune it? and also, how does turning the SOFT-HARD knob on the unit affect the performance or how it works? I searched the forums, but didnt find any answers, and i read the one bov sticky but that only explains how a bov in general works. if anyone knows, please help :-)


The soft hard feature makes the blow off valve release under less/more boost respectively. If you put the BOV on soft it will open with minimal boost, and on the hard setting it will only open under high boost. There are two springs in there and when you tighten down that screw it puts pressure or relieves pressure on those springs to make the bov open with more or less boost.

Now how to tune;
Bring your car to about 10psi and then let of the gas, if you hear a pshhh sound. tighten your BOV another 1/2 turn (hard). Do this until when you boost to 10psi and let off and hear a fluttering noise Like this (choo choo choo). Then relieve the last 1/2 turn and your set. GOT IT?
props to crunchymilk.

The way I was taught to tune the bov is to set your boost at what your normally going to run. Tighten your bov almost all the way to hard. Run the car and build max boost and let off the gas. If you hear a flutter then loosen the bolt to make it more soft. Keep building boost and letting off and loosening the screw to softer untill at full boost you hear a nice clean blow off and at anything under full boost you hear a flutter. I was told this is the correct way because then the bov will not relieve any pressure untill full boost where you want it. I set mine like this and at full boost I get a loud chirp noise followed by a pshhhh. Anything under my full boost is a quick sometimes long flutter.

3am you know what, find yourself a quiet road ( night is the best ) , and happy boosting, adjust the bov until you satafies ( spell check :wink: ).

what are the chances that i break something or lock up the bov? the bov would still open at closed throttle anyways, whether ive tighten or loosened that knob right? usually under heavy boost and i let of hte gas it makes that flutter sound, sorta like the sound that people make to imitate a machine gun, only a little softer and slower, you get what i mean? lol

i messed with it a little bit tonight and set it to hard about 1 full turn, and it sounds nice right now. im gonna mess with it some more tomorrow. maybe one of these days ill run a gm maf and totally vent it....real nice psssshhhhhhhhhhhh!!!!

I dunno if I'm the only person who has noticed this or not but, I have the greddy type S and my bov makes so many different sounds. I get the loud chirp followed by a pshhhhhh when at full boost, a long loud flutter at low-mid boost. Sometimes just a loud PSHHHHH at mid-high boost, and a little flutter followed by a very hard to hear whistle when downshifting sometimes.

i get a whistle all the time when i let off the gas...i figured it was just the turbo spooling down. it sounds pretty cool. my bov makes a couple different sounds...kinda like yours, at full boost it lets out a loud pshhhhhhhhhh and then sometimes just the flutter.

I personally set mine so it will hold full boost but doesnt cause any compressure surge(fluttering) because that can lead to turbo failure over time

So how exactly did you tune yours?