Blow off valve


Full member
Nissan juke
is there any real benefit with a after market bov, mine is a diverter valve and found one the vents to the atmosphere or the direct vent, or in between help me out thanks

also the one im looking at is a afb
After market recirc valve will keep a happier engine over time in my experience ;) Never liked vent to atmosphere's as they vent registered air rather than putting it through the engine like the OE set-up intends and stops over fueling. But if you still want the dump valve woosh, then a cone filter will give that sound ;)
i have a nissan juke
really not much but its what i have

...And there is no problem with that buddy! Despite the 'interesting' appearance, I have driven my other half Uncles Juke and it was lovely. Comfy, nippy enough and good fuel economy. Handled well too!
Nissan has had a covert habit of making good handling cars for years. The Primera was a well kept secret, old man's car image but the roadholding and agility of my 97-98 2.0i SLX was astonishing.
First an atmospheric bov will not make or stop overfuelling with a decent set up.

but there is a reason for atmospheric bov on some cars ( although certainly not on normal stock engines.)

It was originally fitted to cars running very high boost where it can be a problem recirculating that raised pressure

Incedently whilst a sonic cone filter makes a lot of niose when it sucks it cant make a noise like a bov suddenly releasing 2 bar of pressure if that pressure isnt going through the filter.
Funnily enough. When driving my GF's 14 plate Beetle 1.4 tsi, it sounds as though it has an atmospheric dump valve as the noise is rather loud once you let your foot off the throttle.
You need remove the AFM and use speed density/or MAP sensor with non recirculating BOV's

I can only speak about what I know (GTRs) but the afms are certainly capable of running atmospheric BOVs.
The stock recircs dont like much boost over stock so bovs are a well documented mod.
Maybe twin turbo set ups are different
When I still had a stock motor and installed a BOV it drove ok driving normally in traffic but if I got up it and reved it and backed off to change gears if would splutter/hesitate for a bit when I got back on the gas .

This was due volume of air to the AFM told the computer that it had passed was way less due to the bov venting to atmosphere so the hesitation was due to overfueling
Surely that is isnt really an actual bov fault but more an ecu/system fault . The bov is working but the system is not giving enough information to the ecu

Maybe the gtr ecus can cope with that issue because they have a throttle position sensor which possibly overides the afm readings when the throttles off . It must be something like that because my car ran spot on with afms, bovs and a stock ecu
Brian you have to remember it was an 85 car with a distributor and a 2 injector throttle body factory injection and the problem/overfueling went away when I had the Haltec installed and the AFM binned and MAP sensor fitted to the plenum .

It may be that the Nissan computers were more advanced than my Mitsubishi
They are probably a different "generation" as far as technology is concerned

When it came out in 1989 the 32gtr was very advanced for its day and even with the car " limited" by a simple boost restrictor it produced well over 100bhp per litre with twin turbo , awd , rear wheel steering with pretty much everything ran by computers so I suspect they solved that overfuelling issue as well

Similar threads

Please watch this on my YouTube channel & Subscribe.