bov question

oneturboforme · Oct 10, 2011

Couldn't you just use a standard Bov with a very weak spring and reference it to your back pressure port... So if boost is ever higher then backpressure it would open? This would stop turbo bark correct?

WoodBoy · Oct 10, 2011

Turbo surge is air pressure built up and the intake not accepting it so it trys to return back out the turbo. A BOV is electronically controlled plus you have to have one for diesels that will accept the high boost psi

oneturboforme · Oct 10, 2011

WoodBoy said:
Turbo surge is air pressure built up and the intake not accepting it so it trys to return back out the turbo. A BOV is electronically controlled plus you have to have one for diesels that will accept the high boost psi

i get what your saying.. but inorder for it to actually return past the turbo is would have to overcome the backpressure turning the exhuast wheel correct? me theory is this.. okay so on gas engines they have throttle bodys so when you lay off the go fast pedal fast enough there is a pressure diff. that causes the boost to press open the BOV, bleeding pressure so your turbo doesnt bark...

on diesel engines there is no throttle body, just the control of fuel, now im not going to arguee that bd BOV will work better and you can tune it to open on your driving style.. but if you did get lets say a tial 50mm BOV and had back pressure as a "spring" the BOV would open before the turbo had a chance to "bark" correct... this set up probably wouldnt go off as easily as the bd setup but it would save turbo shafts right? or am i just speaking jeberish?

WoodBoy · Oct 10, 2011

You cant reference it to backpressure that is on the exhaust side. Backpressure is usually always going to be higher than boost dependent on your turbo setup. It isnt that the backpressure is higher than the boost, its the amount of psi being pushed back against the turbo shaft and trying to feed back through what wont feed into the cylinder due to restriction. As far as i know it has to be electronically controlled in order to function properly. When you get turbo "bark" essentially you have a certain amount of boost built up for instance 40psi while that the turbo is able to maintain this pressure at a certain rpm "XX,XXX" and when you let off, the 40psi is going to suddenly slow the turbo down as it looks for a means of escape. As soon as the turbo begins to slow down it is no longer able to maintain that amount of boost and the air pressure is able to force past the turbo creating the "bark". A BOV opens at this time electronically to allow the air to escape via the BOV vs backfeeding through the turbo.

NotStock · Oct 10, 2011

WoodBoy said:
You cant reference it to backpressure that is on the exhaust side. Backpressure is usually always going to be higher than boost dependent on your turbo setup. It isnt that the backpressure is higher than the boost, its the amount of psi being pushed back against the turbo shaft and trying to feed back through what wont feed into the cylinder due to restriction. As far as i know it has to be electronically controlled in order to function properly. When you get turbo "bark" essentially you have a certain amount of boost built up for instance 40psi while that the turbo is able to maintain this pressure at a certain rpm "XX,XXX" and when you let off, the 40psi is going to suddenly slow the turbo down as it looks for a means of escape. As soon as the turbo begins to slow down it is no longer able to maintain that amount of boost and the air pressure is able to force past the turbo creating the "bark". A BOV opens at this time electronically to allow the air to escape via the BOV vs backfeeding through the turbo.

What electronic device controls the BOV?

White_monster · Oct 10, 2011

Small solenoid

NotStock · Oct 10, 2011

White_monster said:
Small solenoid

That reacts to what?

Matt · Oct 10, 2011

Run a very soft spring in the bov, drive pressure is higher than boost obviously, pipe drive pressure into the bov, but first run it through some coiled up copper tubing. Under load the bov stays shut, when you let off drive pressure will drop off, boost will overcome the light spring and vent. I know that's how some duramax guys do it

EvilTwins · Oct 11, 2011

NotStock said:
That reacts to what?

It references the throttle position and activates the valve based on perameters you set up. There is a control box that reads the voltage spike from the pedal and reacts accordingly. Three are three points of reference and I can't remember all three. I know I used % of pedal release to activate mine. I think I am set in the 15-20 area.

On a side note, I learned a valuable lesson in setting this up at too little of a pedal release. I had mine set at so that I could snap my foot just a little and get the valve to open. I'll admit it, this was for showing off but it bit me in the arse.

I went to race a mustang and killed him off the line, the truck hit second and due to some nice firm shifting my foot lifted enough to trip the valve and I lost all my boost and all my pride too.

ointlaugh: