BPV/BOV - Recirc vs VTA (Vent to Atmosphere)

[Doel]

One more here that has now changed the BPVs into BOVs by removing the recirc hoses. Took about 30 min, in between taking care of the dog and answering a couple phone calls.

Just took the recirc hoses off and capped the ports on the intake tubes with the 1 1/8" chair tips and hose clamps. It's not that loud at all, in my opinion. No difference in sound driving in Comfort like I normally do on my 30+ mile commute every morning. Definitely no difference in throttle response at all. Still as snappy as ever and picks up when I need it too.

Turn the dial to Sport, run up to about 4k and let off the gas and theres a nice discernible PSSHHH from under the hood, which is nice to hear. It's definitely not earth-shattering, ear-shattering, or anything else shattering....it's just there for the noise. DEFINITELY not as loud as some of the YouTube vids I've seen on removing the recirc hoses, and nowhere near the sound of a proper BOV, but those are coming.

I like it and plan on leaving it just for the noise. I like to hear sounds from my cars, that they are supposed to make, when I drive. It's a quick and easy change to give it the proper turbo sounds it needs, nothing more. Take it for what you will, that's just my 2 pennies.

Do you have an intake? My BPV is still connected to my K&N intake, it's quite loud when I let off the boost! Surprisingly loud.

 

[gilthanis1]

Do you have an intake? My BPV is still connected to my K&N intake, it's quite loud when I let off the boost! Surprisingly loud.

Nope, just took the recirc hoses off for the sound right now. My wife and are planning a pretty big outdoor patio/entertainment area, so car upgrades are waiting.

16'x40' covered patio isnt cheap, but we've been wanting one since we bought our house 5 years ago.

 

[Pnbnationsbest]

Even though I've worked on cars for awhile, this is really the first time I fiddled with altering the BPV and venting to atmosphere versus recirculation, and I wanted to fill you all in on my findings because, despite what people are saying, there is a difference.

First things first: it's really easy to test this back and forth (which is why I did this). Unplug the hose from the BPV, and plug the end of the hose (you can leave it hanging, it's not going to swing around like a horse dong). Et voila, you're a BOV, now. Plug it back in, and you're recirculating like a BPV. Makes what I'm about to tell you very easy to verify, moreso if you're modded/tuned for more boost.

VTA severely drops partial throttle and transient turbo response. It's immediately noticeable at 1/3 throttle that the car doesn't shove me in my seat. It's even more noticeable that at 1/2 to 3/4 throttle, the car does not slam me in my seat, but pushes me harder and harder as boost builds up, aka "turbo lag". Full throttle is mostly unaffected, though, as the BOVs are closed during full throttle. Fortunately, I noticed 1-2 MPG higher overall, which would make sense as there's less boost at partial throttle which requires less fuel.

BPV sees all of the previous paragraph's symptoms completely reversed. However, what I'm also noticing is that this is undoubtedly harder on the turbo during partial throttle. Basically, some of the boost pressure is being "short circuited" (if you will) right back into the turbo to spin it up even faster. This is why this car has so little turbo lag: tiny turbos running recirc. Recirculating spins these tiny things up dramatically faster and explains why partial throttle is sometimes almost full acceleration even though you're only 3/4 down on the throttle. I would bet a larger turbo would also benefit, but not to this degree since physics (bigger turbo, harder to spin up).

My recommendation is to stay on recirc. If you want aftermarket, buy one that lets you switch between the two: recirc for performance; VTA for long distance drives/commuting.

You can look at the lack of serious turbo wear issues in the smaller displacement EcoBoost platforms from Ford. They are all recirculating turbo engines. The smaller 3.5L Taurus and Explorer systems are good parallels to us. They have very low turbo failure rates.