Bov??
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 855
Likes: 35
From: Katy/Houston Texas
Bov??
Does any one run a recirculating BOV and plumb it into the exhaust. Is there any down side to doing this? My blow off is too loud with all of the air coming from it under normal driving conditions and I need a way to quiet it down.
Intermediate
Joined: Mar 2012
Posts: 31
Likes: 0
From: St Petersburg Florida
I would not advise doing that. Probably need to look at getting a different bov and routing to intake of the turbo(s). Turbosmart makes a bunch of nice bovs and there is a recent thread about tial reserc valves super cheap.
Safety Car
Joined: Oct 2001
Posts: 4,945
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From: Dallas/Valley Ranch TEXAS!!!
I run two, 50mm tials, with the S/C your choices are limited, you could design a system that routes the expelled air to the rear of the car, or even to the exhaust as stated, but because of the design of the BOV tself this would take some pretty extensive fab work, but it could be done...
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 855
Likes: 35
From: Katy/Houston Texas
I run two, 50mm tials, with the S/C your choices are limited, you could design a system that routes the expelled air to the rear of the car, or even to the exhaust as stated, but because of the design of the BOV tself this would take some pretty extensive fab work, but it could be done...
Safety Car
Joined: Oct 2001
Posts: 4,945
Likes: 0
From: Dallas/Valley Ranch TEXAS!!!
If you plummed them in at the correct angle 60-70* you wouldn't have to worry about getting pressure back up to the b.o.v. its just how you would capture the b.o.v. of choice, if you changed to a unit with an exhaust "spiggot" it'd be cake, but routing the piping from the b.o.v. to the exhaust could get interesting...
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 855
Likes: 35
From: Katy/Houston Texas
If you plummed them in at the correct angle 60-70* you wouldn't have to worry about getting pressure back up to the b.o.v. its just how you would capture the b.o.v. of choice, if you changed to a unit with an exhaust "spiggot" it'd be cake, but routing the piping from the b.o.v. to the exhaust could get interesting...
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Advanced
Joined: Apr 2009
Posts: 66
Likes: 1
Yeah rerouting it back to your exhaust is a waste of time and just more plumbing you have to deal with. Depending on the BoV that you have you might want to start shopping around for a new one if you dont like the sound yours makes. "its usually dependent on the amount of pressure in the system that is being released based off the valve design...ie small valve or large valve. And the only Issue I can see with recirculating back to your exhaust would be that alot of BoV's depending on manufacturer and design dont always hold boost consistantly, the valve can be forced open and slightly lift alowing air do escape while trying to maintain boost levels, and if recirculated to your exhaust it can cause irregular readings on the wideband or air/fuel monitoring. I would suggest just dumping to atmosphere and possibly going with a larger valve type BoV. And there are always a few tricks like a silencing box that can be retrofitted to the BoV port to reduce the noise, kinda like the stock intake airbox as the silencer.
Safety Car
Joined: Oct 2001
Posts: 4,945
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From: Dallas/Valley Ranch TEXAS!!!
Uhhhhhhhhhh o.k.^^^
P.T. I bet you'd be fine on the back pressure venting the crank case in this manner works, once again with correct angle, so the pressure of the b.o.v. would probably be fine, and you could always run back further as independent, or tie in at the tip if there is concern.. it can be done, just a matter of fabbing it up. Could be a good solution, but not gonna be cheap... Like "any" of this is...LOL
P.T. I bet you'd be fine on the back pressure venting the crank case in this manner works, once again with correct angle, so the pressure of the b.o.v. would probably be fine, and you could always run back further as independent, or tie in at the tip if there is concern.. it can be done, just a matter of fabbing it up. Could be a good solution, but not gonna be cheap... Like "any" of this is...LOL
Safety Car
Joined: Feb 2008
Posts: 3,712
Likes: 3
From: TEXOMA
St. Jude Donor '08-'09
you could weld in a bung and get a back pressure sensor to see it you already have too much back pressure.
http://www.sears.com/shc/s/p_10153_1...=SPM6715752202
http://www.sears.com/shc/s/p_10153_1...=SPM6715752202
Racer
Joined: Dec 2007
Posts: 287
Likes: 10
From: Alamogordo NM
The Mass Airflow Sensor (MAF) needs to measure the amount of air going into the engine. If the BOV is after the MAF, any air that the BOV vents has already been measured by the MAF and taken into fuel mixture calculations. The only way we can ensure that the A/F mixture stays within the parameters the PCM sets is by recirculating this air back into the inlet tract, ergo, recirculation.
Back in the 80's and early 90's, air pumps pumped air into the exhaust to help dilute the exhaust and also supply air to the catalytic converters to assist in the conversion of HCs and CO. Even with these devices pumping air, check valves were required to keep the exhaust pulses from damaging the air supply piping and air pumps. By plumbing the exhaust to the back side of a BOV, it will only be a matter of time before the intense heat and carbon, which a BOV was never designed for, take a toll and either damage the BOV, or prevent it from operating correctly.
Just my 2 cents, it is the internet, after-all.
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 855
Likes: 35
From: Katy/Houston Texas
There has been a lot of advice in this thread, I want to address the nature of a recirculating BOV, and why routing the blown off air the the exhaust is a bad idea.
The Mass Airflow Sensor (MAF) needs to measure the amount of air going into the engine. If the BOV is after the MAF, any air that the BOV vents has already been measured by the MAF and taken into fuel mixture calculations. The only way we can ensure that the A/F mixture stays within the parameters the PCM sets is by recirculating this air back into the inlet tract, ergo, recirculation.
Back in the 80's and early 90's, air pumps pumped air into the exhaust to help dilute the exhaust and also supply air to the catalytic converters to assist in the conversion of HCs and CO. Even with these devices pumping air, check valves were required to keep the exhaust pulses from damaging the air supply piping and air pumps. By plumbing the exhaust to the back side of a BOV, it will only be a matter of time before the intense heat and carbon, which a BOV was never designed for, take a toll and either damage the BOV, or prevent it from operating correctly.
Just my 2 cents, it is the internet, after-all.
The Mass Airflow Sensor (MAF) needs to measure the amount of air going into the engine. If the BOV is after the MAF, any air that the BOV vents has already been measured by the MAF and taken into fuel mixture calculations. The only way we can ensure that the A/F mixture stays within the parameters the PCM sets is by recirculating this air back into the inlet tract, ergo, recirculation.
Back in the 80's and early 90's, air pumps pumped air into the exhaust to help dilute the exhaust and also supply air to the catalytic converters to assist in the conversion of HCs and CO. Even with these devices pumping air, check valves were required to keep the exhaust pulses from damaging the air supply piping and air pumps. By plumbing the exhaust to the back side of a BOV, it will only be a matter of time before the intense heat and carbon, which a BOV was never designed for, take a toll and either damage the BOV, or prevent it from operating correctly.
Just my 2 cents, it is the internet, after-all.
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 855
Likes: 35
From: Katy/Houston Texas
Thread Starter
Burning Brakes
Joined: Aug 2008
Posts: 855
Likes: 35
From: Katy/Houston Texas
I don't have my mind made up, I'm trying to get enough information before I try it. Can you explain to me how the heat is going to get to the BOV, IF the location of the BOV doesn't change (mounted in the front fender) and the exhaust pressure does not overcome the air pressure being put out by the blower, where does this heat you are talking about come from?
Racer
Joined: Dec 2007
Posts: 287
Likes: 10
From: Alamogordo NM
The BOV is not always open. When it is closed, there is only one source of pressure, the exhaust. It is hot, it contains contaminants, and it is going to set up shop on the other side of the BOV piston. It will destroy it.
If your BOV is always open, you have bigger problems, but even then; suction pulses from the engine at idle and cruise will draw in exhaust gas making for a nifty, albeit unnecessary, EGR valve.
A centri does not make boost lower and cruise RPM with a partially open throttle. Therefore, it will be unable to push this exhaust gas out, just like the air pump I alluded to earlier. That is why A.I.R. systems use check valves.
If your BOV is always open, you have bigger problems, but even then; suction pulses from the engine at idle and cruise will draw in exhaust gas making for a nifty, albeit unnecessary, EGR valve.
A centri does not make boost lower and cruise RPM with a partially open throttle. Therefore, it will be unable to push this exhaust gas out, just like the air pump I alluded to earlier. That is why A.I.R. systems use check valves.
Safety Car
Joined: Oct 2001
Posts: 4,945
Likes: 0
From: Dallas/Valley Ranch TEXAS!!!
The setups we are speaking about are all S.D. tuned, the BOV's we run are all open at idle and partial throttle "cruising" and if the bung is at the correct angle only vacuum will be drawn. I've been down this road before with the engine vacuum. If anyone thinks they understand what we are discussing and still thinks/assumes we run a m.a.f. they don't have much of a clue. PT your idea is solid, it'll just be expensive to fab... I say go for it if it bothers you that much, at 29psi on my setup I'm o.k. with the b.o.v.(s) for now, but would consider this mod if I made more major changes, I think 5 major redos is enough for me on this platform. 
I say go for it PT, Taylor will do it right...
I say go for it PT, Taylor will do it right...