I have a HP kit, and the blow off valve has air coming out of it at idle, and I have never noticed it before. Is that normal? tks

 

Sounds like its a bypass valve for a mass-air car. If you are running an external BOV you cant run a mass-air setup.

Whats your setup? Speed-Density or Mas-air?

 

Is the valve adjustable? Most cases you can tighten it down(or shim it for cheaper valves) and take care of that.

 

Mass-air. I think Bosch (it came with the kit). If you rev it a little the bov stops blowing air, and that makes sense to me.

 

Where is the BOV before or after the meter? You cant blow-off metered air into the atmosphere. Sounds like the valve is working correctly.

 

It's before the meter.

 

Sounds right to me.

 

Thanks for your replys

 

thats the way BOV's work. they leak at idle because your motor is pulling vacuume.

 

He's right. Mine is slightly open at idle to.

 

If vaccum keep it open , could you just place a one-way check valve to keep it close at idle?

 

it should be fine. Just keep the filter on it to eliminate the possibility of dirt getting in and causing problems.

 

then how would it open when its supposed to
vac is what opens it when you shift or let off the gas:stickhit:

 

People put oen way valves on the DSM BOVs to keep this issue from causing problems with some cars.

 

A friend of mine gave me this answer. "With the BOV open at idle the turbo is able to spin at a higher rpm than if it was pushing compressed air against the closed throttle plate. That means less turbo lag when you accelerate!"

 

a true "blow-off" valve would not be hooked up to vacuum.

If vacuum is involved, then it is technically a "recirculating" valve that is pressure adjustable.

it's like the argument of "intercooler" vs. "aftercooler".

to use a blowoff valve with a mass air meter with the valve behind the meter, you just don't run a vacuum line to the top side and set the spring to pop-off for whatever boost level you deem appropriate. You can always run a vented line with a 1-way valve to the top of the blow-off valve if you need the additional boost pressure to keep the valve shut under high boost conditions with the throttle open. (the 1-way valve keeps the vacuum from pulling the blow-off valve back open when the throttle closes)

If the only air that dumps is that when the throttle slams shut for the brief 1/4 second, then it will not be a problem for the mass air...you only run into problems when the valve is open and either allowing unmetered air in...or letting metered air out...

been there...done that...

 

I'd try that first

 

:withstu:

Some have set screws like the HKSS and some have different springs you can put in like the tial. You should see more vacuum when you lift off the accel than at idle. I adjusted mine to open at around 13 in/hg. Vacuum at idle is around 12 and drops to 20 when i lift off the pedal.