Another BOV que

That spinning thing that makes all of the cool noises. OE and Aftermarket.

Moderators: Helpinators, Moderators

Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Another BOV que

Post by Elcapitan »

Ok so I looked around and I haven't seen this so I'll ask (Please forgive me if it has been asked)

1. I want to do a dual BOV system, get some additional piping and a T-joint thingie. Have the t-joint before the BPV(in the direction of airflow) and run the t-part of it to a full atmospheric BOV. My reasoning being that i could set it to have the BOV set to operate under high boost so that at low boost the BPV would function as normal. Your take on this fellow DIYers.

2. Based on (1) above, how and/ what sort of tubing would be required. The BOV has large inlet diameter, the BPV small one on both ends and the T-joint would have to connect to both?
MY 91 legacy RS (Erin)
macipusy
Third Gear
Posts: 787
Joined: Wed Aug 22, 2007 9:27 pm
Location: Denver, CO

Re: Another BOV que

Post by macipusy »

Why do that? Just for the noise? I can hardly stand the noise of the BPV....its loud as hell with the coffee mug mod + cone filter intake.

If you are still running a MAF based setup....it's a horrible idea to run any BOV period. In a speed density setup, you can run any BOV.
maciek puszynski

01 Impreza | v6 STi RA | 5mt | ej236t
93 Legacy Turbo | TW | 4eat | ej22t
16 WRX | 6mt | fa20
98 Legacy GT | wagon | 5mt | ej25d


2.36L Turbo - RSTi Build
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

macipusy wrote:Why do that? Just for the noise? I can hardly stand the noise of the BPV....its loud as hell with the coffee mug mod + cone filter intake.

If you are still running a MAF based setup....it's a horrible idea to run any BOV period. In a speed density setup, you can run any BOV.

Hey, thank you for the quick reply. For starters, I love the BOV sound. Also I havent had the chance or time to do the coffee cup mod yet so I do not know how loud the BPV will get. That was my original desired progress on my mods but I happened to get a BOV (from a friend), so now I have it and just need to hook it up.

Random que based on your reply, What exactly is a speed density setup? Pros n cons? If that is covered elsewhere then a link to that would be much appreciated. I will search for it but didn't want to send this post, then search, then if I can't find it come back and send another post. Thanks
MY 91 legacy RS (Erin)
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

Our cars can't run speed/density without a standalone.

Also, they make hybrid BOVs that will do exactly what you're looking for without the extra space and plumbing needed for two. I think HKS and GoFastBits make them, its been a long time since I've looked though.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
CAV3MAN227
Third Gear
Posts: 897
Joined: Fri Dec 25, 2009 8:21 am
Location: Arvada, CO
Contact:

Re: Another BOV que

Post by CAV3MAN227 »

-Just think of speed density as a non-maf based car, like a srt4.
-I was running two bov's for a while. Nothing really special. Had my hks hard piped and the stock bpv. I too, love the sound of bov's, but till I go stand-a-lone, I will stick with the stock bpv, in which I'm running now, or a GFB hybrid valve. Which would be a good option for you instead of running two bov's. Just remember, when using an atmospheric bov, every time your releasing the throttle, your releasing metered air into the atmosphere, which makes you run rich, especially between shifts.
-You can ditch the stock bpv, but if you do, its best to stay with a recirculating bov than a vented/atmospheric bov. for one, it keeps the car running like its suppose to and helps keep the turbo spooled.

-Joe
-I'd rather loose by a mile because I built my own car, than win by an inch cause someone else built it for me. Your car, is your story, so don't let someone else write the book. ~Moog
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

James614, thank you. i have been keeping an eye out for those hybrid ones but i do not have the cash for one at the moment. the extra plumbing will not cost me anywhere near the cost of a hybrid valve so why not? You said you were running two for a while? Why did you stop? Any complications?

CAV3MAN227, you also had the same set up? What do you mean by hard piped? I've heard the different theories on running rich but isn't that for like a split second or less? Also considering I haven't tampered with my stock boost, what would be affected? Also wouldn't running the two as described above mean the rich period would only affect high rpm issues as the BOV would stay closed during slow speed/low rpm driving making it less of a factor?

As far as the fuel thing goes again, aren't production cars set to run slightly rich by manufacturers? And since the problem is computer counting air that isn't there, is it possible to re-program the stock ECU instead?

Hope you all don't mind the 21 questions :-/
MY 91 legacy RS (Erin)
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

I never ran anything but the stock BOV personally, though others have run hybrids and its worked fine.

You're right about it only affecting high boost shifts, that's he whole idea behind a hybrid setup. The thing is, not all cars react the same to a rapid momentary rich condition. I've read some people saying a full atmospheric BOV works fine on their cat, and others say it runs like crap during/right after shifts. Honestly you will probably be fine, but in my opinion deleting the intake resonator and getting a cone filter will give you plenty of wooshing noise mine is loud enough with the Apexi intake that I lost my desire for the GFB hybrid BOV I was looking at a while back :)

Also, most TURBO production cars run rich, yes. But that's irrelevant. The air fuel ratio is a precise measurement and more or less air or fuel going to the engine than it has already measured out is a bad thing. On newer MAF cars you can tune them to expect the difference cause by the BOV under certain conditions, but it will take multiple tunes to get it right.

And no, we can't reprogram the stock ECU like the 99+ cars :(
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
macipusy
Third Gear
Posts: 787
Joined: Wed Aug 22, 2007 9:27 pm
Location: Denver, CO

Re: Another BOV que

Post by macipusy »

A BOV on a MAF based car will run rich not just between shifts, but also when you lift the throttle lightly to adjust load while in boost....usually going up hills. In addition a BPV will help to keep your turbo spinning between shifts by allowing the bypassed air to flow back trough the system.
maciek puszynski

01 Impreza | v6 STi RA | 5mt | ej236t
93 Legacy Turbo | TW | 4eat | ej22t
16 WRX | 6mt | fa20
98 Legacy GT | wagon | 5mt | ej25d


2.36L Turbo - RSTi Build
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

A hybrid BPV/BOV setup *should* recirculate in those situations. I know that's he idea having never run one myself I can't say when exactly it vents and when it recirculates in practice.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
CAV3MAN227
Third Gear
Posts: 897
Joined: Fri Dec 25, 2009 8:21 am
Location: Arvada, CO
Contact:

Re: Another BOV que

Post by CAV3MAN227 »

Elcapitan wrote:CAV3MAN227, you also had the same set up? What do you mean by hard piped? I've heard the different theories on running rich but isn't that for like a split second or less? Also considering I haven't tampered with my stock boost, what would be affected? Also wouldn't running the two as described above mean the rich period would only affect high rpm issues as the BOV would stay closed during slow speed/low rpm driving making it less of a factor?

As far as the fuel thing goes again, aren't production cars set to run slightly rich by manufacturers? And since the problem is computer counting air that isn't there, is it possible to re-program the stock ECU instead?
-What I mean by hard piped is, I have a FMIC. The HKS BOV is part of the IC system, though now, I have swapped it out and the IC pipes have been modified.
-I personally never had a problem running the vented HKS for a couple years, except for sometimes, at partial throttle, the valve wouldn't stay open long enough and I would get turbo flutter. But, I just got rid of it cause I got bored of the noise and knowing it wasn't the best way to run the car.
-About the fuel, I have never had issues. Depending on elevation, stock is around 7-8 psi. Fuel cut is around 12-13 psi. I've maxed out the TD04 on my car, 15-16 psi in 5th gear, and based on my wideband, I still wasn't leaning out. (I have a turbo-xs FCD btw)
-At the end of the day, you can run a atmospheric BOV if you want to, its just not the best idea. You would always want to run richer than leaner, but the point is, there's added benefits of keeping the car, similar to the way it was designed to run. It might be a little harder to pass emissions to btw.

-Joe
-I'd rather loose by a mile because I built my own car, than win by an inch cause someone else built it for me. Your car, is your story, so don't let someone else write the book. ~Moog
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

CAV3MAN227 wrote:
Elcapitan wrote:CAV3MAN227, you also had the same set up? What do you mean by hard piped? I've heard the different theories on running rich but isn't that for like a split second or less? Also considering I haven't tampered with my stock boost, what would be affected? Also wouldn't running the two as described above mean the rich period would only affect high rpm issues as the BOV would stay closed during slow speed/low rpm driving making it less of a factor?

As far as the fuel thing goes again, aren't production cars set to run slightly rich by manufacturers? And since the problem is computer counting air that isn't there, is it possible to re-program the stock ECU instead?
-What I mean by hard piped is, I have a FMIC. The HKS BOV is part of the IC system, though now, I have swapped it out and the IC pipes have been modified.
-I personally never had a problem running the vented HKS for a couple years, except for sometimes, at partial throttle, the valve wouldn't stay open long enough and I would get turbo flutter. But, I just got rid of it cause I got bored of the noise and knowing it wasn't the best way to run the car.
-About the fuel, I have never had issues. Depending on elevation, stock is around 7-8 psi. Fuel cut is around 12-13 psi. I've maxed out the TD04 on my car, 15-16 psi in 5th gear, and based on my wideband, I still wasn't leaning out. (I have a turbo-xs FCD btw)
-At the end of the day, you can run a atmospheric BOV if you want to, its just not the best idea. You would always want to run richer than leaner, but the point is, there's added benefits of keeping the car, similar to the way it was designed to run. It might be a little harder to pass emissions to btw.

-Joe

Roger that... However... No emmisions to pass here :-)
MY 91 legacy RS (Erin)
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

Soo much info though. I just realized that no one actually gave me an idea on how to actually connect it as I want..

As far as the other stuff, I agree with what you guys are saying and I will probably end up with the coffee cup mod and cone filter. In between though I want to experiment. Like I said I ended up in possession of a BOV so my only cost is its plumbing. I'll give it a run and and find out (once I can get it hooked up). The rich thing, what about resetting the ECU and letting it learn that there is too much fuel during valve operation? Anyone tried that?

I like keeping it mostly stock but I could always get a luxury sedan to keep stock and neat. sn't part of the fun and privilege of having our cars their capabilities and our experiments?
MY 91 legacy RS (Erin)
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

The ECU isn't programmed to do that. Its setup for a BPV, so there's no provision for different behavior built-in. There's just no way around that momentary rich condition on the stock engine management.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
CAV3MAN227
Third Gear
Posts: 897
Joined: Fri Dec 25, 2009 8:21 am
Location: Arvada, CO
Contact:

Re: Another BOV que

Post by CAV3MAN227 »

-Experiment all you want. I've done plenty of it myself. There's a lot of info here at this site to learn. I would suggest having gauges, more importantly, boost and a wideband before doing anything. That way, you don't hurt or blow anything up.
-As far as connecting the aftermarket BOV, is all up to you, use your imagination. There's not enough info given and depends on supported mods and setup. There's just to many variables. All I can say is, keep the BOV exit hole as close to the TB as possible, or you might shorten the life of the turbo and or get turbo flutter.

-Joe
-I'd rather loose by a mile because I built my own car, than win by an inch cause someone else built it for me. Your car, is your story, so don't let someone else write the book. ~Moog
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

James614 gotcha. Guess that means looking into standalone ecus and heavy spending on the engine huh?
Caveman227, guess im off to have some fun.

I heard/ read somehwere that the 90 somthing impreza sti v3/6 was pretty much a bolt on replacement for our engines..Would that be an option?
MY 91 legacy RS (Erin)
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

92-95 WRX EJ20G, 96/97 WRX EJ20K, and Forester EJ20G engines are all great power options. But they still run MAFs and are designed for recirculating BPVs :)

I actually have a 93 WRX complete engine and trans sitting in my garage right now to go in my wagon.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

James614 wrote:92-95 WRX EJ20G, 96/97 WRX EJ20K, and Forester EJ20G engines are all great power options. But they still run MAFs and are designed for recirculating BPVs :)

I actually have a 93 WRX complete engine and trans sitting in my garage right now to go in my wagon.
How different would those be to my EJ20G? And what of the sti one, is that MAF based too and designed for BPVs?

Ok so I was trying to do some more thinking and thought of an idea...hear me out (Even if it sounds stupid)
- What if we close off the hole where the BPV sends the air back into the system, and instead extend the pipe and put that air in...before the MAF? Would that then allow the ecu to read the air being fed back into the system and reduce amount of metered fuel? Would that the allow us to eliminate (or reduce) that momentary rich spurt? What do you guys think?

While on the extending pipe note, how does keeping the BOV exit hole as close to the TB as possible reduce (possibly) the life of the turbo?
MY 91 legacy RS (Erin)
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

The STI engine is the same electronically, just tuned for more boost and higher RPMs.

As for recirculating before the MAF, that's a strange idea. Sounds like it could work, but if your gonna plumb it back into the intake, why not have it go back in just before the turbo like it supposed to?
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

James614 wrote:The STI engine is the same electronically, just tuned for more boost and higher RPMs.

As for recirculating before the MAF, that's a strange idea. Sounds like it could work, but if your gonna plumb it back into the intake, why not have it go back in just before the turbo like it supposed to?
Because you'd be taking it back into the intake to allow the ecu to learn the bypassed air as extra...Im assuming it would then lean the fuel slightly...Once it learns this you would be able to switch to BOV?
MY 91 legacy RS (Erin)
cj91legss
Fifth Gear
Posts: 6317
Joined: Fri Jun 20, 2008 8:17 am
Location: Lakewood, Wa 98439
Contact:

Re: Another BOV que

Post by cj91legss »

I think pressurized air could cause the MAF to malfunction over time.
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
Elcapitan
First Gear
Posts: 52
Joined: Wed Oct 27, 2010 2:54 pm

Re: Another BOV que

Post by Elcapitan »

cj91legss wrote:I think pressurized air could cause the MAF to malfunction over time.
I don't think so but I'm open to explanations or theories. If the pressure can damage it by proximity then would increasing the proximity of the inlet solve that? Also Wouldn't ram air from an aftermarket CAI have the same effect then (Damaging the MAF)?
MY 91 legacy RS (Erin)
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

I don't think that would be an issue, as the prussure would quickly dissipate before it hits the sensor.

However, tricking the ECU isn't going to work like you're thinking. I'm 99% sure it isn't aware of when the BPV is operating, and so it would just notice the air fuel ratio go crazy for a moment and then continue as normal. Might pull timing, but its not going to "remember" exactly when it happens and compensate for it at the same times and in the same way when you change to a BOV. It will see a change and adjust to that change. It would be better to just run the BOV than to try fooling the ECU in my opinion. You aren't gonna break the motor by running rich occasionally.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
cj91legss
Fifth Gear
Posts: 6317
Joined: Fri Jun 20, 2008 8:17 am
Location: Lakewood, Wa 98439
Contact:

Re: Another BOV que

Post by cj91legss »

I'm trying to think in the electrical aspect of it tho. If the sensor is constantly getting short bursts of air, internally the electrical components are working harder then not and so on. Like a light bulb, you sit there and turn it off and on it's going to go out. I'm just wondering if the sensor could potentially do the same thing.
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
James614
Fourth Gear
Posts: 1744
Joined: Sun Jun 10, 2007 4:35 am
Location: Arkansas

Re: Another BOV que

Post by James614 »

Possibly, but the electronic stuff is typically the least affected by having to work rapidly. It's the electromechanical things like solenoids and relays which tend to fail when worked hard.
93 Touring Wagon (EJ20G 5spd Swap) -- Finally back and running strong as ever!

05 Outback 2.5XT 5spd -- Now the wife can have her SUV and get in on the turbo Legacy goodness at the same time.
Legacy777
Site Admin
Site Admin
Posts: 27748
Joined: Tue Oct 15, 2002 11:37 am
Location: Houston, Tx
Contact:

Re: Another BOV que

Post by Legacy777 »

You will not be able to trick the ECU by dumping the bypass valve vent before the MAF. The ECU just does not work that way, period.

As far as damage to the MAF, Douglas Vincent ran a blow through MAF setup and you can do it, but the added pressure can cause accelerated wear of the MAF components. With the setup your talking about I'd be more concerned with turbulence and that altering the air flow reading across the MAF sensor.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
Post Reply