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Why two blow off valves?

Munna

By Munna,
in General Automotive Discussion

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SS8_Gohan Grand Master

SS8_Gohan

Posted
Posted

Post a reply, don't do a quick reply. Look for the "Additional Options" box and click on the "manage attachments" button. Should be able to browse for the pic on your computer and then click ok. The pic will be attached to the post.

hope that helps, cheers.

RaseR Collaborator

RaseR

Posted
Posted

Hey Munna,

I bought my R32 with the same setup, standard recirculating BOV and an atmo BOV (non-adjustable HKS Super BOV on mine) in the same place as yours. The reason people set it up this way is because they want to run an atmo BOV for some reason (high boost application or they just like the sound), but also want the car to retain idle quality and not to run mega rich between gear changes because the standard BOV will still work to a certain degree. (The cars ECU expects a certain amount of air to be recirculated by the std BOV at these points).

Didn't really hamper performance of the car, but it did hamper performance of the HKS BOV as it hardly even went off most of the time!

So it really seemed like a pointless setup, I ended up removing it for that reason.

RaseR Collaborator

RaseR

Posted
Posted

Yeah I had the same thing - on 16psi the HKS would work alot harder.

As far as limits of the std BOV - from what I've heard it's pretty variable....I thought mine was leaking at 12psi but have since discovered it isn't. I've heard they hold up to 17psi standard, but can't confirm it, some say more, some say less...

There's a thread on SAU that describes a modification you can do to the BOV to make it hold a bit more boost at the cost of causing it open up a little slower:

http://www.skylinesaustralia.com/forums/sh...read.php?t=9634

.....Additionally, the Americans seem to love our std Skyline BOV as well - it's a Mitsubishi design and comes on a few models they have over there, a few things they've done to make them hold more boost:

Crush it in a vice!

http://www.geocities.com/MotorCity/Garage/...4/crushBOV.html

Physically drill out the small air leak inside the bov and vent it to the atmosphere for slow openning and holds boost up to 30psi, not bad!!

http://www.thedodgegarage.com/turbo_bov_mod.html

RaseR Collaborator

RaseR

Posted
Posted

Hey CerealKiller,

Yeah, tightening it up so far that it can't open will definitely nullify it!! Of course if you have a pod filter the std bov is quite loud too.....

A friend and I tried this on his DR30 Skyline which has a adjustable Sheepdog BOV, we were able to prevent it from openning at all, such was the extent of the adjustment. Not necessarily good for the turbo (it has no std bov)....but so much quieter, b4 it sounded like a steam train venting every time it went off!

Personally on my car I just went to a jap wrecker and got a piece of intake piping without the mount/hole for an atmo BOV and then sold the BOV!

Munna Rising Star

Munna

Posted
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Yeah I had the same thing - on 16psi the HKS would work

RaseR

RaseR Blocked the little hole off on the standard blow off valve as in the the posts you listed and I could hardly beleive how much faster the turbo spolled up. Heaps more responive now and atmo blow off valve is louder.

RaseR Collaborator

RaseR

Posted
Posted

Hey Munna, great result!

I had limited success with the BOV mod (I tried it after removing my atmo bov), seemed to hold boost a little better and opened up later - but I ended up reverting back because on my car it also caused infrequent part throttle surging. So many people have had totally different results from doing this mod.....it's interesting, I wouldn't mind trying the 'Dodge Garage' BOV mod as described in the third article I posted earlier, but haven't had the inclination as yet!!

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