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Subaruz an BOV

Fuji Heavy Industry tech talk - STi, WRX, Forester etc.

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SPEC_C
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Subaruz an BOV

Postby SPEC_C » January 3rd, 2007, 9:14 pm

yea 2ners a mechanic tell me it not reccommended to put a BOV in a subaru az it interfers wit d proper functionin of d car...
how true iz dis,anyone wit experience ur info will be greatly appreciated
i have a 2003 forester...bless

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STi-N
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Postby STi-N » January 3rd, 2007, 10:15 pm

i hav ah BOV on my 2003 forester and it works perfectly
no problems at all

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Postby Zh@ne » January 3rd, 2007, 10:46 pm

if i had a Subaru i would of be able to say :cry: (in time though :twisted: )

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JWT
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Postby JWT » January 3rd, 2007, 10:57 pm

i have a blow off on my subaru no complaints but seriously if if you are looking to max out every ounce of power keep the recirculating valve
some say subarus do not like it but i have no probs so far

:mrgreen:
http://www.scoobytnt.com/
the subaru guys are online on that forum you can check there you will get alot of help

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Postby SPEC_C » January 4th, 2007, 12:18 am

tanx guys for all d info....SUBARU all d way

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Postby nissan-man » March 28th, 2007, 8:50 am

um.....i dont have a Blow off or anything...but I have read that Blow offs are not supposed to be as good because the car(ECU) doesnt compensate for the air that is Blown off making you burn rich...but its very minor. They still doing research into it to see how bad it can affect oyur engine....but if you real serious about cars....keep the bypass/recirculating valve as JWT said.

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Postby Rx » March 28th, 2007, 11:01 am

is not really good for any car , not only scoobys..... I'm referring to performance here

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Postby nissan-man » March 28th, 2007, 1:04 pm

yeah....only put it if u want to impress ppl....it sounds kewl..but when u consider performance...the recirrcualting valve is best.....think about it....does any top of the line cars for instance super cars come with blow offs? I think not. So u whould know what to do now.

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Postby Sunrise City Rider » April 1st, 2007, 9:10 pm

nissan-man wrote:um.....i dont have a Blow off or anything...but I have read that Blow offs are not supposed to be as good because the car(ECU) doesnt compensate for the air that is Blown off making you burn rich...but its very minor. They still doing research into it to see how bad it can affect oyur engine....but if you real serious about cars....keep the bypass/recirculating valve as JWT said.



It is not Minor...Its does nothing but hurt your engine's tune and why shorten the life of your engine just to hear the loud PFFFFFFSSSSHhhhh sound everytime you shift...

This is only affected by Subarus with a Mass Air Flow Sensor in the Intake Pipe...Which is the majority of Turbo Subarus...If you use a Standalone ECU, that can eliminate the MAF and use only a Map Sensor, you will have no problem using a "To Atmosphere" BOV...

If your BOV isn't holding boost...Take a hammer and smash in the top of it...The Bronze cap holds the spring in and by crushing it in, you are pushing the spring further against the valve...This will hold the valve shut when running higher boost pressures and costs you $0.00...

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Postby nissan-man » April 2nd, 2007, 8:45 am

yeah Sunrise City Rider.....thanks for explaining that. But this goes for all cars with the MAF sensor right?

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havokkk
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Postby havokkk » April 2nd, 2007, 11:14 am

nissan-man wrote:But this goes for all cars with the MAF sensor right?

hey nissan-man... BOVs and RCVs both function to keep the centrifugal compressor away from it's surge point (for a given speed)... both prevent the reversals that accompany the decay in flow pattern at the discharge volute, seen during surges.

the choice of an RCV/BOV should be made against your EFI type (MAF/air-flow, or MAP/speed-density).

if your fuel comp adds fuel based on measured air-flow, and not manifold pressure, fuel delivered during shifts far exceeds the req'd amt., as the air flow measured includes vented air... AFRs will plummet and perhaps closed-loop correction will mitigate. and as Sunrise City Rider stated, MAP EFIs can vent the compressor discharge flow wherever they choose as flow isn't used the calculate fuel requirements :D

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Postby Sunrise City Rider » April 2nd, 2007, 4:26 pm

All MAF equipped engines are affected by this problem...

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Postby nissan-man » April 4th, 2007, 10:05 am

wow u guys are pretty knowledgeable....i din really understand what havokk said but i kinda did but not really.......teach me...lol

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Postby Alpha_2nr » April 8th, 2007, 9:37 am

This is only affected by Subarus with a Mass Air Flow Sensor in the Intake Pipe...Which is the majority of Turbo Subarus...If you use a Standalone ECU, that can eliminate the MAF and use only a Map Sensor, you will have no problem using a "To Atmosphere" BOV...


Sunrise is correct. Using an EMS in tandem with a MAP sensor should eliminate the BOV problem. The MAP is the clincher in this case, as the MAF sensor normally creates the shortcomings when running with a fully vented bov. However, I don't think one can run a MAP just like that on a Subaru ecu....so...ergo my point about an EMS.

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Postby Sunrise City Rider » April 8th, 2007, 11:45 am

Just FYI, the Turbo Subarus in question use both a MAP and MAF...

Also, if you want to hear some type of Whoosh, You can run a Cone-Type Filter and hear the stock Bypass Valve operate as you shift...

I don't like to mess with the "Calibrated" size of the intake piping on my Subie, so I took a stock Air Intake Box and trimmed off all the plastic that makes the box, leaving only the tube that the MAF bolts into...Then I just bought a universal Stainless Steel Filter and clamped it around that tube...

The Tube is part of the box's top and is molded into the box...One can easily trim this to reveal the tube by itself...

Its been shown that intakes that use a different size pipe diameter than stock lead to Lean Conditions due to the OEM Map being tuned for that specific intake pipe diameter...

Lots of Geek-type info, but this is what keeps your engine healthy and your car on the road...

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Postby Alpha_2nr » April 8th, 2007, 2:22 pm

Just FYI, the Turbo Subarus in question use both a MAP and MAF...


Not to my knowledge. At least not the older ones (02/03). I can't say for newer ones.

I don't like to mess with the "Calibrated" size of the intake piping on my Subie, so I took a stock Air Intake Box and trimmed off all the plastic that makes the box, leaving only the tube that the MAF bolts into...Then I just bought a universal Stainless Steel Filter and clamped it around that tube...


This is interesting, and will definitely give you a "louder" intake sound, but it is also arguably less efficient for your engine. Think about it, your stock intake, as quiet as it may be, still pulls air from the outside of the engine (remember it has a ram air "mouth" right under the bonnet, just in front the car. A Cone type filter inside the car will draw in more hot air. :wink:

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Postby Sunrise City Rider » April 8th, 2007, 10:58 pm

well I do have this on my hood to keep the outside air coming in...
[img::]http://www.rs25.com/forums/attachment.php?attachmentid=84[/img]




[img::]http://www.rs25.com/forums/attachment.php?attachmentid=26883[/img]

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Postby Sunrise City Rider » April 8th, 2007, 11:00 pm

[img::]http://www.rs25.com/forums/attachment.php?attachmentid=26886[/img]

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Alpha_2nr
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Postby Alpha_2nr » April 9th, 2007, 3:05 am

^^Not seeing the pics. But I'm guessing that you use a duct (NACA maybe?) of some kind to keep cool air flow in?

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Postby JWT » April 9th, 2007, 10:31 am

lordie understand this
below 20psi not recommended you have a BOV

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Postby Sunrise City Rider » April 9th, 2007, 5:46 pm

Also, the Intake Volume is more important than Temperature when it comes to turbocharged cars...Its not the same as an N/A car, since the compressed air will rise to temps that are over 150degrees F or even closer to 200degrees F before it enters the Intercooler...

Removing restrictions in the filter and intake path is most important...The Intake duct on Subarus are restricted and made of cheap plastic that will melt and develop cracks with age and increased pressure...

I use a Perrin Intake Duct and it works great...Install isn't too easy but nothing someone with a socket set, pliers and an afternoon can't tackle...

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havokkk
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Postby havokkk » April 19th, 2007, 1:10 pm

Sunrise City Rider wrote:Removing restrictions in the filter and intake path is most important...The Intake duct on Subarus are restricted and made of cheap plastic that will melt and develop cracks with age and increased pressure...

such an important point to note as fuel mixtures will lean with cracks on the compressor inlet re. this corrugated plastic tube is located after the MAF sensor and before the compressor...

Sunrise City Rider... could you re-post pics of install?

and nissan-man... just realized which post you meant :D

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Postby Sunrise City Rider » April 22nd, 2007, 1:29 pm

This is a shot of my engine bay that shows the Blitz Air Filter in place of the AirBox...Again, I took a dremel to the airbox and removed all the plastic around the tube that is molded into the airbox to fit a Round inlet of the Open Air Filter...

http://www.tamparacing.com/photopost/sh ... user/12007

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Postby DuAL StaR » April 23rd, 2007, 1:36 pm

SPEC_C, u still lookin for a bov for the subie well call me i can order the blitz bov that bolts on fr u 796-7419

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