Adjusting the Blow off valve

[turbodsm18]

Alright, I have a greddy type S replica blow off valve. Its actually an RVM blowoff valve. I was wondering what I need to have the top screw adjusted to. I know on the greddy that the adjustments go from hard to soft but what does that mean. I running 14psi if that makes a difference, but I am just looking for that original Greddy Type S pinnnnggggggg sounds

-Kevin-

 

[turbodsm18]

Anybody, I read about how there were supposed to be 6 to 7 threads showing, is this right

 

[MyBeatGSX]

It should be adjusted full soft. Take the screw completely out, then reinstall, tighten until it just starts to engage the preload spring, and you're done.



This next part isn't directed at you (so don't take it personal), its for everyone else reading, because I'm tired of explaining this simple principle, I want to forever be able to post a link to this topic every time the question comes up...



The hard/soft adjustment has NOTHING to do with how much boost you're running and it is NOT for changing the sound.

The adjustment has only to do with how much vacuum is required to open the BOV. If you run 15,000psi of boost, the valve will not open. The valve won't open because the diagram also has 15,000psi through the vac/boost reference line that is pushing it closed, plus the preload of the spring. It will not open due to any level of boost. DO NOT adjust your preload by the level of boost you're running.

What the preload is used for, is controling how easily the BOV opens under vacuum. The idea is adjust it so that the BOV is not being held open at idle. These engines don't make much vacuum so this isn't a problem for us. Set to full soft the BOV will open any time the vacuum spikes, regardless of whether you were boosting or not. Mine is constantly open during deceleration, making a nice PEEEEEEEEEE noise. In fact the Type RS (with no extra preload) pops at anything over 20in/hg, which is perfect because I idle at 19in/hg. That means it opens easily even at 1psi of boost, which is exactly how it should be. It also opens during ever off boost shift as well, which makes a funny pop noise because all you hear is the valve but no discharge. This is exactly how they should operate, it gives the most consistant opening and ensures you will never surge even at very low boost. Everyone that sets it tight thinking they're making it "hold boost" is really just hurting response and smooth operation.

 

[djseclipse]

I also have a knock off type s. It should be set closer to hard, just above the point when you get surge. Trust me I took everyone's advise about full soft just to the point when the screw puts pressure on the spring and then 1 full turn to hard. Ran it like this for a while, car felt sluggish. So when I did a boost leak test everything leaked out the bov pass 10psi. Adjusted about 6 full turns toward hard, no leak, no surge even at 5psi and the car feels ALOT better. Whistles every time! Guess these knockoffs are a little different, not sure if they have both springs or not. I am sure full soft would work on the real Greddy but not the look a likes. Hope this helps!

 

[bluetlr2001]

The adjustment has only to do with how much vacuum is required to open the BOV.

I have to say differently. You may have more expericence in messing with bovs than me. But in my experience with a greddy, apexi, and rfl. If i adjust them to soft they open at full boost. Each time i tried adjusting them like you explain it satrted leaking around 10psi or so. But like i said thats just from my experience.

 

[ericbev]

Ill toss in my obligatory BOV adjustment post for good measure and say no more. Its bed time.

How do I adjust my BOV correctly?

The "harder" the setting (the deeper the adjustment screw), the less prone the valve will be to being blown open and the greater the change in pressure needed to open it. Set too soft, the valve could possibly be blown open at high RPMs. Set too hard, the valve may flutter or not open at all. Any fluttering from too hard of a setting will be most noticeable during light throttle changes since there is only a small change in pressure on either side of the diaphram. The more you let off the gas and/or the more quickly you let off, the greater/sharper the change in pressure and the increased ability for the valve to open flutter-free. For the very least potential valve flutter, adjust the spring as light as possible without it being blown open for your setup and boost level. The fluttering sound you will hear is also known as compressor surge and is bad news. So basically, loosen it up enough that you dont hear fluttering at very low throttle releases, but make sure its hard enough that it doesnt start blowing off boost. It shouldnt be hard to find this "neutral" spot. The fluttering is very noticeable and so is the valve blowing off boost. Go on a backroad where its you and the road (nice and quiet), carry the allen wrench and box wrench with you, and play with it till you are satisfied.

What is compressor surge?

Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. It is commonly described as a chuffing or fluttering sound depending on the severity. You will know it when you hear it.

The EVOmoto site has a nice little writeup on the "single spring mod" with a little added info. Enjoy.

 

[zippyshoe]

Ill toss in my obligatory BOV adjustment post for good measure and say no more. Its bed time.

How do I adjust my BOV correctly?

The "harder" the setting (the deeper the adjustment screw), the less prone the valve will be to being blown open and the greater the change in pressure needed to open it. Set too soft, the valve could possibly be blown open at high RPMs. Set too hard, the valve may flutter or not open at all. Any fluttering from too hard of a setting will be most noticeable during light throttle changes since there is only a small change in pressure on either side of the diaphram. The more you let off the gas and/or the more quickly you let off, the greater/sharper the change in pressure and the increased ability for the valve to open flutter-free. For the very least potential valve flutter, adjust the spring as light as possible without it being blown open for your setup and boost level. The fluttering sound you will hear is also known as compressor surge and is bad news. So basically, loosen it up enough that you dont hear fluttering at very low throttle releases, but make sure its hard enough that it doesnt start blowing off boost. It shouldnt be hard to find this "neutral" spot. The fluttering is very noticeable and so is the valve blowing off boost. Go on a backroad where its you and the road (nice and quiet), carry the allen wrench and box wrench with you, and play with it till you are satisfied.

What is compressor surge?

Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. It is commonly described as a chuffing or fluttering sound depending on the severity. You will know it when you hear it.

The EVOmoto site has a nice little writeup on the "single spring mod" with a little added info. Enjoy.

Thought I would include a link to the EVOmoto writeup mentioned above: http://www.evomoto.com/tech_info.php?tPath=1&tech_id=7

 

[turbotalon_]

I haven't adjusted mine yet but I am going to tighten it later because its blowing up at 8psi which is getting really annoying. Are you saying if I tighten it that won't fix my problem?? I boost at 15psi when it was closed. If it's blowing open at 8psi and the screw won't fix it what do I do?????

 

[MyBeatGSX]

The adjustment has only to do with how much vacuum is required to open the BOV.

I have to say differently. You may have more expericence in messing with bovs than me. But in my experience with a greddy, apexi, and rfl. If i adjust them to soft they open at full boost. Each time i tried adjusting them like you explain it satrted leaking around 10psi or so. But like i said thats just from my experience.

I just did a boost leak test. 25psi, no leaks. My Type RS preload screw is set hand tight exactly how I described above.

 

[chuckg]

I have a type S and i have it set sort of right in the middle. Just soft enough to not flutter and surge like ericbev said, and just hard enough to hold boost and blow off nice and crisp. Just go out and mess with it and youll get it figured out.

 

[James Bondage]

I did the single spring mod on my replica type-s and adjusted it from there. Works so much better for me now.

If you do the mod be careful as to not tear the diaphram!