How many people run an air filter on their BOV?

***Poodles*** · August 19th, 2012, 08:08 AM

Originally Posted by CyFi6

" It operates
in a normally open condition. This means that it is designed to remain open
under vacuum conditions."
Pulled directly from their site.

These are also the idiots on youtube saying that it's fine for it to be open (hey idiots, that's going to cause lag)

***CyFi6*** · August 19th, 2012, 01:41 PM

Originally Posted by Poodles

These are also the idiots on youtube saying that it's fine for it to be open (hey idiots, that's going to cause lag)

Not sure exactly what your argument is. You don't have to like the BOV but are you saying that the manufacturer of the BOV doesn't know how to properly operate it? Fact is it is designed to be open under vac conditions which includes idle, decel, and cruising. Every bypass valve I have had ex Bosch has operated in the same way.

***Dan_Gyoba*** · August 19th, 2012, 01:57 PM

Okay, so it's open. Doesn't this mean a vacuum leak?

So what the upshot is that you don't want to run a BOV if you're still on the AFM. You want to stick to a bypass valve, like stock or the Bosch, unless you have and are using a recirculation fitting. (Glad that I'm doing that, then.)

**Supracentral** · August 19th, 2012, 02:00 PM

Originally Posted by CyFi6

Not sure exactly what your argument is. You don't have to like the BOV but are you saying that the manufacturer of the BOV doesn't know how to properly operate it? Fact is it is designed to be open under vac conditions which includes idle, decel, and cruising. Every bypass valve I have had ex Bosch has operated in the same way.

And all of the valves that operate in this manner are designed to be used with a re-circulation fitting.

Simply put, if you operate a valve that operates like this, it shouldn't be vented to atmosphere.

(But most people won't do that because it doesn't "sound cool".)

**MPR** · August 20th, 2012, 08:54 AM

On our MK1 MR2 with 4agze converted to turbo with 4age NA intake, we ran a Bosch oem Bov (used on porsche 911 turbo's) and they are syncronic. They purposely stay half open at idle and part throttle. But the moment there is any boost, it closes instantly. This is done to improve throttle response on off-idle tip-in and improve throttle response in general. (tip-in is where we noticed it helped the most). It is also meant to be recirculated so there is no fear of sucking anything up. We ran it open to atmosphere because we didn't care and weren't worried about it sucking anything up. lol.

Obviously if it's your daily driver and/or you have put a lot of money into it, recirculate it or filter it.

***Poodles*** · August 20th, 2012, 09:24 AM

Originally Posted by MPR

On our MK1 MR2 with 4agze converted to turbo with 4age NA intake, we ran a Bosch oem Bov (used on porsche 911 turbo's) and they are syncronic. They purposely stay half open at idle and part throttle. But the moment there is any boost, it closes instantly. This is done to improve throttle response on off-idle tip-in and improve throttle response in general. (tip-in is where we noticed it helped the most). It is also meant to be recirculated so there is no fear of sucking anything up. We ran it open to atmosphere because we didn't care and weren't worried about it sucking anything up. lol.

Obviously if it's your daily driver and/or you have put a lot of money into it, recirculate it or filter it.

Yep, the difference between a by-pass valve and a blow-off (or pop-off) valve.

***RazoE*** · August 20th, 2012, 09:59 AM

Recirculate it and be done with it.

**MPR** · August 20th, 2012, 11:50 AM

Also, if you're running any type of MAF or AFM that measures the intake air prior to the turbo, you SHOULD be recirculating the BOV to just after the MAF/AFM and prior to the turbo inlet anyways. Otherwise it's giving extra fuel for all that metered air you just dumped out to atmosphere when you let off and will cause hesitation/extreme rich condition when shifting.

***RazoE*** · August 20th, 2012, 12:09 PM

Don't forget STALLING when shifting into neutral for too long.

***destrux*** · August 20th, 2012, 02:55 PM

The OEM valve on my DSM and Mazdaspeed3 stay open at idle and low throttle cruise. The valve closes as soon as you tip into the throttle, so it doesn't cause lag. It's only open under full vacuum. I think last time I checked it closes around 15 inches of mercury. I have my Greddy set this way too, it closes as soon as you tip in. If you set the spring too loose it will cause lag though. No reason to set it that loose though, but I'm sure some people do by mistake.

I should probably mention I have my valve in fast opening mode. The lower hose barb is connected to the IC pipe (well, technically I have mine drilled internally to do this so that's why that barb is capped in my picture). Someone who doesn't run it in fast opening mode might not see the valve open at idle. The two OEM valves on my other cars are designed the exact same way with the lower chamber connected internally to IC pipe pressure.

I run low boost, so I can use that mode, if you run high boost a valve plumbed like that will usually leak so most people run the lower chamber vented, or they run a valve with no lower chamber. Those valve usually stay closed at idle.