Recirculating BOV
Racetracks
Joined: Nov 2002
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From: How long is a piece of string?
Re: Recirculating BOV
Don't use a recirc unless you have a car with a mass air flow sensor, there isn't any need to otherwise.
If you need a recirc, and want something aftermarket, Forge Motorsport makes really nice stuff. Not that popular in the US (UK company) but really popular in Europe on street cars, rally cars, track cars. I'd take Forge parts over most other BOVs any day.
Thread Starter
Slow?^_^mabye
Joined: Jul 2004
Posts: 123
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From: Fayetteville, North Carolina
Re: Recirculating BOV
What? Exhaust air? Intake leaks? What the hell are you even talking about?
Don't use a recirc unless you have a car with a mass air flow sensor, there isn't any need to otherwise.
If you need a recirc, and want something aftermarket, Forge Motorsport makes really nice stuff. Not that popular in the US (UK company) but really popular in Europe on street cars, rally cars, track cars. I'd take Forge parts over most other BOVs any day.
Don't use a recirc unless you have a car with a mass air flow sensor, there isn't any need to otherwise.
If you need a recirc, and want something aftermarket, Forge Motorsport makes really nice stuff. Not that popular in the US (UK company) but really popular in Europe on street cars, rally cars, track cars. I'd take Forge parts over most other BOVs any day.
Thread Starter
Slow?^_^mabye
Joined: Jul 2004
Posts: 123
Likes: 0
From: Fayetteville, North Carolina
Racetracks
Joined: Nov 2002
Posts: 15,668
Likes: 0
From: How long is a piece of string?
Re: Recirculating BOV
Get a atmo BOV if it's for a B16; there isn't any real reason to use a recirc unless you want to keep the BOV really quiet.
I'll explain the thought process here:
If you have an engine with a mass air flow (MAF) sensor, the air mass is measured in the intake (before the turbo, etc). If you have an atmo (purge to atmosphere) BOV, the BOV will purge intake air that has already been measured by the MAF sensor. So instead of that measured air going into the engine, it goes somewhere else, and the ECU is not happy because the previous MAF sensor readings don't match what it thinks the engine should be doing. Can cause jerking, hesitation, all sorts of annoying things because the ECU is confused from getting conflicting information. This is why recirc valves are used; the air from the BOV bypasses the turbo and goes back to the outlet (the turbo side) of the MAF sensor. Thus all the air that has already been measured by the MAF makes it into the engine eventually, whether it has gone through the BOV or not.
BUT
If you have an engine with only a manifold pressure (MAP) sensor, like your B16, all the ECU cares about is the manifold pressure. If the BOV purges to atmosphere, the ECU doesn't care because it will detect that change in manifold pressure and act accordingly. So you have the simple, nice case, and can use whatever BOV you want.
Oh, and stock WRX/STi BOVs work well too, they're recirc, have a mounting flange, and can handle quite a bit of flow. I'm not sure how much boost they will handle, but that should be easy to find on the NASIOC/ClubWRX/i-Club/ScoobyMod forums.
I'll explain the thought process here:
If you have an engine with a mass air flow (MAF) sensor, the air mass is measured in the intake (before the turbo, etc). If you have an atmo (purge to atmosphere) BOV, the BOV will purge intake air that has already been measured by the MAF sensor. So instead of that measured air going into the engine, it goes somewhere else, and the ECU is not happy because the previous MAF sensor readings don't match what it thinks the engine should be doing. Can cause jerking, hesitation, all sorts of annoying things because the ECU is confused from getting conflicting information. This is why recirc valves are used; the air from the BOV bypasses the turbo and goes back to the outlet (the turbo side) of the MAF sensor. Thus all the air that has already been measured by the MAF makes it into the engine eventually, whether it has gone through the BOV or not.
BUT
If you have an engine with only a manifold pressure (MAP) sensor, like your B16, all the ECU cares about is the manifold pressure. If the BOV purges to atmosphere, the ECU doesn't care because it will detect that change in manifold pressure and act accordingly. So you have the simple, nice case, and can use whatever BOV you want.
Oh, and stock WRX/STi BOVs work well too, they're recirc, have a mounting flange, and can handle quite a bit of flow. I'm not sure how much boost they will handle, but that should be easy to find on the NASIOC/ClubWRX/i-Club/ScoobyMod forums.
Last edited by Fabrik8; Apr 15, 2008 at 11:18 PM.
Thread Starter
Slow?^_^mabye
Joined: Jul 2004
Posts: 123
Likes: 0
From: Fayetteville, North Carolina
Re: Recirculating BOV
Get a atmo BOV if it's for a B16; there isn't any real reason to use a recirc unless you want to keep the BOV really quiet.
I'll explain the thought process here:
If you have an engine with a mass air flow (MAF) sensor, the air mass is measured in the intake (before the turbo, etc). If you have an atmo (purge to atmosphere) BOV, the BOV will purge intake air that has already been measured by the MAF sensor. So instead of that measured air going into the engine, it goes somewhere else, and the ECU is not happy because the previous MAF sensor readings don't match what it thinks the engine should be doing. Can cause jerking, hesitation, all sorts of annoying things because the ECU is confused from getting conflicting information. This is why recirc valves are used; the air from the BOV bypasses the turbo and goes back to the outlet (the turbo side) of the MAF sensor. Thus all the air that has already been measured by the MAF makes it into the engine eventually, whether it has gone through the BOV or not.
BUT
If you have an engine with only a manifold pressure (MAP) sensor, like your B16, all the ECU cares about is the manifold pressure. If the BOV purges to atmosphere, the ECU doesn't care because it will detect that change in manifold pressure and act accordingly. So you have the simple, nice case, and can use whatever BOV you want.
I'll explain the thought process here:
If you have an engine with a mass air flow (MAF) sensor, the air mass is measured in the intake (before the turbo, etc). If you have an atmo (purge to atmosphere) BOV, the BOV will purge intake air that has already been measured by the MAF sensor. So instead of that measured air going into the engine, it goes somewhere else, and the ECU is not happy because the previous MAF sensor readings don't match what it thinks the engine should be doing. Can cause jerking, hesitation, all sorts of annoying things because the ECU is confused from getting conflicting information. This is why recirc valves are used; the air from the BOV bypasses the turbo and goes back to the outlet (the turbo side) of the MAF sensor. Thus all the air that has already been measured by the MAF makes it into the engine eventually, whether it has gone through the BOV or not.
BUT
If you have an engine with only a manifold pressure (MAP) sensor, like your B16, all the ECU cares about is the manifold pressure. If the BOV purges to atmosphere, the ECU doesn't care because it will detect that change in manifold pressure and act accordingly. So you have the simple, nice case, and can use whatever BOV you want.
thank you so much man, i really feel like i learn something jus now, so i know now what i will do. do u know if the RFL will hold boost well on this forum i hear ppl say yea and on superhonda and hondaswap some say no whats your opinion
Racetracks
Joined: Nov 2002
Posts: 15,668
Likes: 0
From: How long is a piece of string?
Re: Recirculating BOV
If you want to go higher, your results may vary. Many BOVs have a preload adjustment that can set the spring preload higher so the BOV won't start to open under high boost conditions.
Please don't get an RFL, they're obnoxious. Don't be "that guy" who can be heard from 3 blocks away at every shift. Keep it tasteful.
Thread Starter
Slow?^_^mabye
Joined: Jul 2004
Posts: 123
Likes: 0
From: Fayetteville, North Carolina
Re: Recirculating BOV
Depends on how much boost you're planning on.. For less than roughly 15 psi, pretty much everything on the market will work great.
If you want to go higher, your results may vary. Many BOVs have a preload adjustment that can set the spring preload higher so the BOV won't start to open under high boost conditions.
Please don't get an RFL, they're obnoxious. Don't be "that guy" who can be heard from 3 blocks away at every shift. Keep it tasteful.
If you want to go higher, your results may vary. Many BOVs have a preload adjustment that can set the spring preload higher so the BOV won't start to open under high boost conditions.
Please don't get an RFL, they're obnoxious. Don't be "that guy" who can be heard from 3 blocks away at every shift. Keep it tasteful.
Racetracks
Joined: Nov 2002
Posts: 15,668
Likes: 0
From: How long is a piece of string?
Re: Recirculating BOV
Sweet, trade it for something different in the classifieds if its an RFL. Really, it doesn't matter what type of BOV you get as long as it does the job. There really isn't any need to spend a penny more than you have to finding one that works. It won't give you more power, or anything like that. Its job is really simple and either it works or it doesn't. People put way too much time and money into a part that is so trivial. Spend the money on something that will give performance gains.
I'm a little opinionated about stuff like this; I'm a very practical, no bullshit person and hate marketing hype and misinformation.
I'm a little opinionated about stuff like this; I'm a very practical, no bullshit person and hate marketing hype and misinformation.
Thread Starter
Slow?^_^mabye
Joined: Jul 2004
Posts: 123
Likes: 0
From: Fayetteville, North Carolina
Re: Recirculating BOV
Sweet, trade it for something different in the classifieds if its an RFL. Really, it doesn't matter what type of BOV you get as long as it does the job. There really isn't any need to spend a penny more than you have to finding one that works. It won't give you more power, or anything like that. Its job is really simple and either it works or it doesn't. People put way too much time and money into a part that is so trivial. Spend the money on something that will give performance gains.
I'm a little opinionated about stuff like this; I'm a very practical, no bullshit person and hate marketing hype and misinformation.
I'm a little opinionated about stuff like this; I'm a very practical, no bullshit person and hate marketing hype and misinformation.