"The BIG BOV thread" (Where all bov question threads get merged) - Page 759

This is a discussion on "The BIG BOV thread" (Where all bov question threads get merged) within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; i have a modded 02 wrx, what would happen if i made the bypass valve into a blow off valve?...

  1. #11371
    Registered User
    Join Date
    Mar 2012
    Posts
    9

    BOV

    i have a modded 02 wrx, what would happen if i made the bypass valve into a blow off valve?

  2. Remove Advertisements
    ClubWRX.net
    Advertisements
     

  3. #11372
    Registered User Pylonpounder's Avatar
    Join Date
    Aug 2010
    Location
    Factoryville, PA
    Posts
    380
    Okay.....What I probably should do, is give you the link to Unabombers Manifesto. What I'm also going to do, is explain. Your car has a little sensor in the air intake system. It's called a MAF, or mass air flow sensor. It measures the amount of air coming in, and tells the computer how much fuel to inject into the cylinders to compensate. When you have a blow off valve, the air that the computer and engine THINK is there....isn't. It gets released into the atmosphere, causing your engine to, unsurprisingly, run wrong. The use of the MAF sensor also makes most cold or ram-air intakes pretty pointless, disregarding certain applications and tuning. If you really want the BOV sound, do the intake snorkus delete. Or get a compatible (compatible being the key word) intake and get a tune for it.

  4. #11373
    ClubWRX.net Vendor adam@kronosperformance's Avatar
    Join Date
    Nov 2005
    Location
    Princeton, NJ
    Posts
    3,983
    I Support ClubWRX
    Quote Originally Posted by Pylonpounder View Post
    Okay.....What I probably should do, is give you the link to Unabombers Manifesto. What I'm also going to do, is explain. Your car has a little sensor in the air intake system. It's called a MAF, or mass air flow sensor. It measures the amount of air coming in, and tells the computer how much fuel to inject into the cylinders to compensate. When you have a blow off valve, the air that the computer and engine THINK is there....isn't. It gets released into the atmosphere, causing your engine to, unsurprisingly, run wrong. The use of the MAF sensor also makes most cold or ram-air intakes pretty pointless, disregarding certain applications and tuning. If you really want the BOV sound, do the intake snorkus delete. Or get a compatible (compatible being the key word) intake and get a tune for it.
    Just to clarify

    The issue isn't having a blow off valve per say that causes an issue. The whole thing about "running rich between shifts" makes no sense on modern vehicles where your injectors don't open when you have your foot off the accelerator (example, when your foot is off the throttle, its using momentum of the engine to de-accelerate and doesn't use any fuel during that period until it finds itself needing fuel to keep the engine steady like if you all of a sudden came to a stop and hit idle RPMs).

    The problem with blow off valves is that they are badly designed for MAF based vehicles. They either open too early, too much, too late and if its off at all, it causes essentially an air leak at that moment. On a bypass valve, it would just re-circulate to keep fueling working properly.

    To the OP, If you were to infact do what you're trying to do, you would need to block your recirculating tube...but still, you will have driveability issues.
    ClubWRX.net's #1 Vendor! www.kronosperformance.com sales@kronosperformance.com Call/Text 732-742-8837 We Offer a Military Discount
    Our Facebook | Our Twitter | Our Instagram | Our Pinterest
    Our featured brands
    RALLY ARMOR | BC RACING | PERRIN | MISHIMOTO | GRIMMSPEED

  5. #11374
    Registered User
    Join Date
    Mar 2012
    Posts
    9
    i have a forge motorsport BOV for my car, i read that its one of the most compatible for wrx. i just wanted to see if i could undo my bypass valve where it does go into the tube that recirculates it.

  6. #11375
    SPT for the win! lashak's Avatar
    Join Date
    Jul 2011
    Location
    Maryland
    Posts
    63
    I Support ClubWRX
    see i see so much back and fourth about BOV's but recirculating or air venting should not matter because when your in boost the valves should be closed one way or another?. and the stock BOV in my 2010 WRX is not terrible BUT its not great. i do see boost leaking some on my gauge so it you have a solid metal BOV replace the plastic stock one i cant think that at would hurt? thoughts?
    Speed has never killed anyone, suddenly becoming stationary… that’s what gets you.

  7. #11376
    Registered User
    Join Date
    Feb 2012
    Location
    Troy, MI
    Posts
    25
    I was looking at a 02 wrx today, and there was build up of gear oil on whatever is directly behind the oil pan.

    He has a Greddy BOV, could that be the cause of the leaking oil?
    Looking for an 02-05 wrx in the Michigan area!

  8. #11377
    ClubWRX.net Vendor adam@kronosperformance's Avatar
    Join Date
    Nov 2005
    Location
    Princeton, NJ
    Posts
    3,983
    I Support ClubWRX
    Quote Originally Posted by WrxOnWrxOnWrx View Post
    I was looking at a 02 wrx today, and there was build up of gear oil on whatever is directly behind the oil pan.

    He has a Greddy BOV, could that be the cause of the leaking oil?
    No. BOVs don't have anything to do with oil...if there is oil coming out of the BOV, that means that he must be experiencing a ton of blow by...meaning there may be something wrong with the engine. Thats just the extreme but there is more than likely no oil coming out of BOV.
    ClubWRX.net's #1 Vendor! www.kronosperformance.com sales@kronosperformance.com Call/Text 732-742-8837 We Offer a Military Discount
    Our Facebook | Our Twitter | Our Instagram | Our Pinterest
    Our featured brands
    RALLY ARMOR | BC RACING | PERRIN | MISHIMOTO | GRIMMSPEED

  9. #11378
    Registered User
    Join Date
    Feb 2012
    Location
    Troy, MI
    Posts
    25
    well I heard that blow off valves cause leaks, not necessarily do the leaking it's self.
    Looking for an 02-05 wrx in the Michigan area!

  10. #11379
    Registered User
    Join Date
    Mar 2012
    Location
    Estonia | Tallinn
    Posts
    27
    Quote Originally Posted by WrxOnWrxOnWrx View Post
    well I heard that blow off valves cause leaks, not necessarily do the leaking it's self.
    Yes, BOV's can leak air, but not oil.

  11. #11380
    Registered User
    Join Date
    Feb 2012
    Location
    Troy, MI
    Posts
    25
    Ok thanks for the quick help guys
    Looking for an 02-05 wrx in the Michigan area!

  12. #11381
    Registered User Weaver's Avatar
    Join Date
    Mar 2010
    Location
    Maryland
    Posts
    96
    Question? Honest opinions should I stay stock and return the BPV i just installed or Leave it on? Turbo XS 50/50 BPV. 2012 WRX 5 Door. Current Mods: Cobb AP Stage 1, CNT Catback, Cobb SF Intake. Looking to go stage 2 eventually...

  13. #11382
    Registered User Impreza2.0's Avatar
    Join Date
    Nov 2008
    Location
    Maine
    Posts
    905
    I sold my RFL-H last year because I couuld not find a way to get anything useful out of it at all other than the noise it made.

    I spent several months with poorer fuel economy and a dirty hood liner.

    It also smelled aweful.

    I replaced it with a Greddy RZ with an RS hotpipe (fully reciprocated bypass valve)

    It makes NO sound, and does NOT leak.

    I am at 20psi scramble with 18psi as DD setting.

    If you are under 17psi at all times, the stock BPV is flawless.
    It (stock BPV) can begin to whine around 20psi. I heard this before I messed with mine, didn't listen, bought the TurboXS valve, modded it by having the baseplate remachined (turboXS is famous for sloppy CNC work), and adding a proper Subaru BPV downspout. It was as good as possible with a non-adjustable hybrid BOV/BPV, and it was still bad news.

    Stick with reciprocating/bypass type until you have an externally gated, front mount intercooled turbocharger with a MAP instead of a MAF, and you will be OK for a blow off valve when ALL of that is done. There are folks with FMIC still using BPV due to the quietness and LEGALITY of not venting unburnt fuel into the air.

    Oil sludging at the IC/throttle coupling is a sign that you have engine trouble that MUST get looked into if you want to keep her running.
    That area might have a thin film of oil at most on a properly kept motor.
    If there is oil behind the BPV inside the intercooler, that's BAD!

    Oil outside of that area is not coming from the valve. That sounds like a loose oil galley plug ont he top of the block... did anyone ever install any gauges in that car, then remove them?

    That's a common issue with aftermarket oil galley plugs, especially if they are eBay no-namers.
    that is IF they weren't installed properly, and that's a tight spot to work in, so shade-tree mechanics often rush it.

    hope this helps

    10x what EJ257 said, list the mods, then we can see if there IS a reason for a billet valve.
    Otherwise, stock BPV works reliably for almost an infinite lifetime.
    It also doesn't screw up your stock tune, cause driveability issues, etc...

  14. #11383
    Registered User Weaver's Avatar
    Join Date
    Mar 2010
    Location
    Maryland
    Posts
    96
    Thanks that helps alot... Being I need driveablity over anything and the amount of mileage i put on a vehicle i will the only engine modifications i will be doing besides my current intake and cat back is a downpipe so I will be returning the BOV and using that money for something else... Any suggestions on what to spend the 200$ with haha?

  15. #11384
    UnBanned Sinister's Avatar
    Join Date
    Nov 2006
    Location
    Denver Metro Area
    Posts
    17,628
    I Support ClubWRX
    Quote Originally Posted by Impreza2.0 View Post
    I sold my RFL-H last year because I couuld not find a way to get anything useful out of it at all other than the noise it made.

    I spent several months with poorer fuel economy and a dirty hood liner.

    It also smelled aweful.

    If it smelled aweful, and you had a dirty hood liner from it... then you are blowing through a lot of oil into your turbo inlet. This isn't the BOV's fault. It's the fact that you don't have a catch can / air oil separator

    I replaced it with a Greddy RZ with an RS hotpipe (fully reciprocated bypass valve)

    It makes NO sound, and does NOT leak.

    I am at 20psi scramble with 18psi as DD setting.

    If you are under 17psi at all times, the stock BPV is flawless.
    It (stock BPV) can begin to whine around 20psi. I heard this before I messed with mine, didn't listen, bought the TurboXS valve, modded it by having the baseplate remachined (turboXS is famous for sloppy CNC work), and adding a proper Subaru BPV downspout. It was as good as possible with a non-adjustable hybrid BOV/BPV, and it was still bad news.

    Stick with reciprocating/bypass type until you have an externally gated, front mount intercooled turbocharger with a MAP instead of a MAF, and you will be OK for a blow off valve when ALL of that is done. There are folks with FMIC still using BPV due to the quietness and LEGALITY of not venting unburnt fuel into the air.

    externally gated, front mount intercooled don't matter. I have a top mount and an internally gated blouch dominator 1.5XT-R with 22psi, and I have a 50/50 BOV.

    As well... you shouldn't be blowing unburnt fuel into the air. Only oil. We don't have an EGR system (exhaust gas recirculation system) so there is absolutely no reason that you should have any fuel any further up the intake tract than the end of the intake manifold runners.


    Oil sludging at the IC/throttle coupling is a sign that you have engine trouble that MUST get looked into if you want to keep her running.
    That area might have a thin film of oil at most on a properly kept motor.
    If there is oil behind the BPV inside the intercooler, that's BAD!

    May or may not be anything more than PCV blow by. The only other thing that would cause oil in the intake would be blown turbo seals. If the intake tract has never been cleaned, and it's got 100k miles in PCV blow by building up... it could start to look pretty raunchy in there.

    Oil outside of that area is not coming from the valve. That sounds like a loose oil galley plug ont he top of the block... did anyone ever install any gauges in that car, then remove them?

    That's a common issue with aftermarket oil galley plugs, especially if they are eBay no-namers.
    that is IF they weren't installed properly, and that's a tight spot to work in, so shade-tree mechanics often rush it.

    hope this helps

    10x what EJ257 said, list the mods, then we can see if there IS a reason for a billet valve.
    Otherwise, stock BPV works reliably for almost an infinite lifetime.
    It also doesn't screw up your stock tune, cause driveability issues, etc...
    Replied to you in bold.
    Kevin
    Moderator
    Sinister's Blowoff Valve FAQ
    WRX Gas Mileage FAQ
    Sinister's Progress Thread - 430whp 429wtq - Sold
    Firearms Enthusiasts Thread

    The Sheriff's Star at the bottom left corner rates a user's reputation.
    If you found a user's post to be helpful or quite the opposite, please make it known to them by clicking the Star!

  16. #11385
    Registered User
    Join Date
    May 2012
    Posts
    1

    Question about a BOV

    Not really sure if i am using this correctly i am new to forums but i just have a quick question i am wondering if it would be better to get a BOV or Diverter valve on my currently stock 2004 WRX if anyone knows what one would be better that would be great.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •