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Evo X factory blow off valve

Posted: Mon Jun 14, 2010 11:09 pm
by JaCe
I was doing some Wiki reading and came across: http://en.wikipedia.org/wiki/Blowoff_valve

Based on this, is the Evo X factory BOV actually just a compressor bypass valve? i.e. the sound of fluttering is just coming through the intake.

These are some pictures taken from my Injen thread:
Image Image Image Image Image

Posted: Tue Jun 15, 2010 10:27 am
by billy boy
so lesson learnt - if a cop asks you 'do you have a blow off valve?' then the answer is 'no, i have a bypass valve' ;)

your engine bay is looking great though!

Posted: Tue Jun 15, 2010 8:29 pm
by JaCe
Thanks for the tip :) Wonder if they'd notice that small pod filter though...

Posted: Tue Jun 15, 2010 11:47 pm
by WillF
I used to own a 300zx tt and was led to believe the following?? am i right or mind blowingly deluded?

I thought turbo'd cars came with "re-circulative valves" from the factory as valves that vent gasses into the atmosphere are illegal ( not the fact they make noise) so my question is, is a re-circ vale the same as a bypass valve

basically a re-circ puts gasses back in to the turbo thus slowing the spooling of the turbo.

where as a dump valve or blow off valve or what ever you want to call them vent the gasses out of the system thus not affecting the spooling of the turbo thus supposing better performance.?

Posted: Fri Jun 18, 2010 1:40 pm
by JaCe
What you describe sounds a lot like what I have in my Evo (i.e. the bypass valve)

Posted: Fri Jun 18, 2010 3:30 pm
by WASABI
A by-pass valve is a Blow Off Valve that is plumbed back from what I understand.

By-pass valve is technically the correct terminology, but (In most tuner circles - at least the ones I'm part off) they are still BOVs that are plumbed back.

There is so much different terminology that is getting around is does get very confusing. Some other terms I've heard of is "pop off valve" or "diverter valve" - I believe the diverter valve terminology is commonly used for European cars.

As always, I don't claim to be 100% correct so happy to be corrected :)

Posted: Fri Jun 25, 2010 8:25 pm
by JaCe
I suppose there's probably just a bit of stigma regarding the name 'blow off valve' (i.e. hoons) so they may try to avoid that.

Posted: Tue Jun 29, 2010 9:12 am
by McCoy
WASABI wrote:A by-pass valve is a Blow Off Valve that is plumbed back from what I understand.

By-pass valve is technically the correct terminology, but (In most tuner circles - at least the ones I'm part off) they are still BOVs that are plumbed back.

There is so much different terminology that is getting around is does get very confusing. Some other terms I've heard of is "pop off valve" or "diverter valve" - I believe the diverter valve terminology is commonly used for European cars.

As always, I don't claim to be 100% correct so happy to be corrected :)


Waste gate would be another term. Just google some old footage of the Ford Sierra's at Bathurst, they had a fantastic soundtrack of the engine, exhaust and waste gate dumping.

Posted: Tue Jun 29, 2010 12:39 pm
by smithsy
JaCe wrote:Thanks for the tip :) Wonder if they'd notice that small pod filter though...


I'd say it's safe to say if they pop your bonnet its a $84 fine and/or a defect notice on the car...

Posted: Tue Jul 06, 2010 9:16 am
by WASABI
McCoy wrote:
WASABI wrote:A by-pass valve is a Blow Off Valve that is plumbed back from what I understand.

By-pass valve is technically the correct terminology, but (In most tuner circles - at least the ones I'm part off) they are still BOVs that are plumbed back.

There is so much different terminology that is getting around is does get very confusing. Some other terms I've heard of is "pop off valve" or "diverter valve" - I believe the diverter valve terminology is commonly used for European cars.

As always, I don't claim to be 100% correct so happy to be corrected :)


Waste gate would be another term. Just google some old footage of the Ford Sierra's at Bathurst, they had a fantastic soundtrack of the engine, exhaust and waste gate dumping.


Was down at Bathurst the other week & saw the old B&H Sierra Cosworth race car... Still such a beautiful thing :)

Posted: Tue Jul 06, 2010 9:21 am
by Blakey
McCoy wrote:
WASABI wrote:A by-pass valve is a Blow Off Valve that is plumbed back from what I understand.

By-pass valve is technically the correct terminology, but (In most tuner circles - at least the ones I'm part off) they are still BOVs that are plumbed back.

There is so much different terminology that is getting around is does get very confusing. Some other terms I've heard of is "pop off valve" or "diverter valve" - I believe the diverter valve terminology is commonly used for European cars.

As always, I don't claim to be 100% correct so happy to be corrected :)


Waste gate would be another term. Just google some old footage of the Ford Sierra's at Bathurst, they had a fantastic soundtrack of the engine, exhaust and waste gate dumping.


isn't a wastegate used for when you have 2 turbos, so when the littleer turbo get to its limit, the wastegate opens so you dont blow it up when the larger turbo takes over?

Posted: Thu Jul 08, 2010 3:27 pm
by McCoy
No, not necessarily but that is one application.