BOV BLOW OFF VALVE QUESTION......ONCE AGAIN

[sledheadgeorge]

jonny r - you may want to consider cutting a coil or two off the spring. I did and it made a world of difference on how well the BOV functioned. If my memory serves me, I think I ended up cutting two coils off the spring. My brother did the same thing on his ahd his works well also.

Same for me. Works better with 2 coils cut off.

 

[HAMMER]

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Very informative link:

http://www.gofastbits.com.au/index.php?parentid=tech_info&option=tech_info

Blow-off valve myth #1: One of the biggest misconceptions about blow-off valves is that you need to tighten the spring to run higher boost. This is totally incorrect (at least, for a GFB valve anyway), as you can see from the last paragraph, at full throttle, the pressure on the top and bottom of the valve is equal, therefore cancelling itself out. So no matter what boost pressure you run, the valve will stay shut.

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The TurboXS Type S Blow Off Valve (BOV) we are using operates like this:

MODE 1: (engine creates source vacuum at idle and partial throttle positions)
Vacuum on one side and pressure on the other side of the BOV piston = Valve Open

MODE 2: (engine vacuum turns to pressure above partial throttle positions)
Pressure on both sides of the BOV piston = Valve Closed

The SPRING pressure can be used to adjust the "transition point" of the modes

 

[Skydog]

jonny r - you may want to consider cutting a coil or two off the spring. I did and it made a world of difference on how well the BOV functioned. If my memory serves me, I think I ended up cutting two coils off the spring. My brother did the same thing on his ahd his works well also.

Same for me. Works better with 2 coils cut off.

YES AND YES!!!!

 

[Jonny Rocket]

I believe I cut some coils off but would have to double check. I will put this on my "to do" list before I go riding.

Thanks guys,

J.

 

[Blue shadow]

If your springs are to weak they will rise at different times.With boost this may not be a good idea.

 

[woodsrider]

In theory, the only spring pressure you need is to hold the valve closed during idle conditions. As boost pressure rises the boost pressure acts on both sides of the poppet. With a balanced piston (equal areas on each end of the poppet exposed to the pressure) the spring tension holds the poppet closed. When you "chop" the throttle a vaccuum occurs on the spring side and the pressure in the charge intake opens the valve (allowing the turbine to spin freely) pressure drops until the spring pressure closes the BOV. Some racers actually run without the spring and allow air to leak through the valve to enhance turbo spool up.

 

[powderlites]

Blowwoff valve

We use Blowoff valve that is wide open at idle so turbo is spooled up for crisp throttle response!
6" vaccum is wide open. Don't like alot of them where valve is closed at idle. 2 Canadian cents worth!!

http://www.powderlites.com/turbokits.html

 

[Anonymous]

Re: Blowwoff valve

We use Blowoff valve that is wide open at idle so turbo is spooled up for crisp throttle response!
6" vaccum is wide open. Don't like alot of them where valve is closed at idle. 2 Canadian cents worth!!

http://www.powderlites.com/turbokits.html

Is a bosch type bov can be adjusted to act this way?

 

[Skydog]

Man i might have to play with that is year! Open at idle.