BOV Question

[Guest]

Hi all,

I recently had my car mapped and as part of that installed a K&N induction kit (note: it was mapped after installing the induction kit). Now after accelerating and letting off I get a lot of air coming back through the filter giving an extremely similar sound to a dump valve (but obviously it’s not), so I was wondering is this because the recirc valve can’t handle the amount of air? Would fitting an actual dump valve help air not come back out of the filter?

+ if I do get a dump valve now, do I need to go back to the remapper? 

 

Thanks

Matt

[Sandals]

What you're hearing is the recirc valve recirculating pressurised air back into the intake, which is normal. You hear a lot of noise from an induction kit as the standard airbox with resonator kills a lot of intake and recirc noise. 

 

[Guest]

11 hours ago, Sandals said:

What you're hearing is the recirc valve recirculating pressurised air back into the intake, which is normal. You hear a lot of noise from an induction kit as the standard airbox with resonator kills a lot of intake and recirc noise. 

 

This makes a lot of sense, thanks for the response.

Based on that, I’m guessing there is zero benefit in changing the standard recirc valve for an after market one or a dump valve then?

 

[Sandals]

Only thing it does is increase the noise... can potentially cause lumpiness if you go full vent to atmosphere as you're releasing air that has been measured so it over fuels very briefly. 

[Guest]

10 hours ago, Sandals said:

Only thing it does is increase the noise... can potentially cause lumpiness if you go full vent to atmosphere as you're releasing air that has been measured so it over fuels very briefly. 

Is this in anyway bad for the engine? I’ve seen adjustable valves so I guess they are slightly better? Someone is selling a forge full vent to air valve for £80 so I’m debating whethers it’s worth it or not. 

[Sandals]

I used an adjustable one and it was fine (ran around 75% vent), changed to 100% when i got it remapped. If you go full vent, you could be fine... or it could be a bit lumpy. Engine wise? Debateable... i don't think it does, all it does is very briefly run rich so you may get an extra loud pop every now and again

[Guest]

14 hours ago, Sandals said:

I used an adjustable one and it was fine (ran around 75% vent), changed to 100% when i got it remapped. If you go full vent, you could be fine... or it could be a bit lumpy. Engine wise? Debateable... i don't think it does, all it does is very briefly run rich so you may get an extra loud pop every now and again

Great, cheers mate! I have have to invest in an adjustable so I can play around with it a bit

[Sandals]

5 minutes ago, Matt91uk said:

Great, cheers mate! I have have to invest in an adjustable so I can play around with it a bit

I would say it's a better investment. Last thing you want to do is buy a fully atmos one and your car doesn't like it.

This is the one I used:

http://www.scoobyparts.com/performance/gfb-tuning-products/gfb-respons-tms-bov-impreza-wrx-08-on