[How to] Install a blow-off valve

BriinumsBo

New member
the adjustment is for vacuum!!!
the BOV opens when a vacuum is reached in intake manifold (when the throttle valve is closed before the intake manifold). when there is a vacuum, the BOV opens, no mater how much boost or no boost is in the intercooler. the adjustment is for how much vacuum needs to be to open the valve. if your car doesnt run on high vacuum, it should be adjusted to softer setting so that it opens at all. but it if the adjustment is too soft, the boost pressure would push against and open the BOV, because of the soft resistance - in result the turbo would leak boost.
 

Sheng

New member
So then another question :oops:, how would you know what setting on the bov would be ideal for the vaccum? is it when it stops leaking during idle?

Sheng
 

BriinumsBo

New member
Sheng":2uvdz6a1 said:
So then another question :oops:, how would you know what setting on the bov would be ideal for the vaccum? is it when it stops leaking during idle?

Sheng

no. during idle the car is in vacuum and it should be open (except if you vent to atmosphere and use AFM, then you will go LEAN). some BOVS open only when there is both vacuum in intake manifold AND boost in intercooler.
you dont want to leak it under boost conditions. at intake manifold vacuum it should open.
you have to make sure that when you accelerate (intake manifold gets positive pressure) the valve closes
 

Sheng

New member
ahh k now i understand completely, since at idle it's at vaccum during acceleration it goes towards 0 and at boost it's + in pressure. k i was a complete noob when it came to this and trying to figure it out :oops:

thanks

Sheng
 

Gary

Moderator
Not really. BOV opens not just when there is vacuum in the intake manifold. There has to be pressure in the intercooler too. That mean it opens only when there is a difference in pressure between intercooler pipe and behind the throttle plate. It only occurs when you close the throttle plate abruptly (lift of your right gas pedal after boosting).
So, at idle, BOV should be completely close. If it is open at idle, you should adjust the spring tension so that it is close. While boosting, it should not leak (same pressure on both sides).
 

BriinumsBo

New member
Gary":1625f7qt said:
Not really. BOV opens not just when there is vacuum in the intake manifold. There has to be pressure in the intercooler too. That mean it opens only when there is a difference in pressure between intercooler pipe and behind the throttle plate. It only occurs when you close the throttle plate abruptly (lift of your right gas pedal after boosting).
So, at idle, BOV should be completely close. If it is open at idle, you should adjust the spring tension so that it is close. While boosting, it should not leak (same pressure on both sides).

well it really depends on the BOV. good quality ones really are designed to open when there is boost and intake vacuum at the same time, but there are others that open when there is any vacuum no matter what pressure is after the turbo..
 

SleepingTurbo

New member
ok so i get that its kinda smart to recirc. ive got an MR2 bpv. if i connect that to my I/C piping by way of t-hose, what needs to be done to get it recirced and wwhere can i hook it up so it works? or is just the t-hose fitting enough?
 

Rallly

New member
SleepingTurbo":2hqwpu5a said:
ok so i get that its kinda smart to recirc. ive got an MR2 bpv. if i connect that to my I/C piping by way of t-hose, what needs to be done to get it recirced and wwhere can i hook it up so it works? or is just the t-hose fitting enough?



Did you ever figure this out?
 

Lamont

New member
Rallly":2kzgjlbl said:
SleepingTurbo":2kzgjlbl said:
ok so i get that its kinda smart to recirc. ive got an MR2 bpv. if i connect that to my I/C piping by way of t-hose, what needs to be done to get it recirced and wwhere can i hook it up so it works? or is just the t-hose fitting enough?



Did you ever figure this out?

It's not too hard at all, you just use the plugged vacuum line on the rear right of the intake manifold. Here is my current setup using a MR2 BPV:

 

Rallly

New member
Thanks for posting this. Okay so it's tough to see but where does the top nipple hose run too?
What is going on with the lower small nipple and right side big port?
 
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