who has done this? Have you had any issues? Did you notice any better spooling? I am trying to decide if I want to add one to the engine setup I am building.(spyder intake, TMIC)

bypass valves are better as they vent not to the atmosphere but into the intake. quieter too.

bypass valves are better as they vent not to the atmosphere but into the intake. quieter too.

 

Okay. How did you plumb it? and did you notice any gains? Trying to decide if I want to do one.

bypass valves and blow off valves add no performance what so ever. they simply vent excess air into the atmosphere or back into the intake.

I know it doesn't add any total HP. I've read they help keep the turbo spooled up during shifts, and help eliminate backpressure on the turbo during closed throttle between shifts. That's when boost*backs up* and actually slows the turbo and puts strain on it. BOV extends the life of the turbine. That's what I've been reading but I have never run one.

A bypass valve eliminates compressor surging when the throttle is slamed shut, not just when shifting. Improves turbo life, and makes obnoxious sounds when vented to the atmosphere.

I should have been more clear. I was actually thinking about a bypass type valve which would vent back to the uncompressed side of the turbo intake. No obnoxious noises. Even though that can be kinda cool in Condoleeza(Rice)kinduv way

 

So how has anyone set theirs up?

the stock bypass hose out of a wrx goes in the right direction, but it needs to be extended a little bit and have a 90* elbow.

mine looks like this, it went from my 02 WRX TMIC into the "duct B" in the intake snorkel (the cup thing).

here's a close up:

0. wrx bypass hose

1. 3/4" PCV pipe, not sure on length

2. 3/4" to 1" pcv coupler

3. 1" to 1 1/2" 90* elbow.

I had a Turbo XS BOV on my RX. I noticed no issues with it venting to the atmosphere as far as stumbling and such. It actually sounded pretty nice compared to a few cheaper BOVs I've heard. It had more of a flutter sound to it and on an old Subaru, it got a lot of weird looks:grin:

I've never had one installed on my cars

 

Okay. How did you plumb it? and did you notice any gains? Trying to decide if I want to do one.

No obnoxious noises. Even though that can be kinda cool in Condoleeza(Rice)kinduv way

 

So how has anyone set theirs up?

 

#1 Award, First Use of Condoleeza Rice and Turbos On This Board.

They are even COOLER when you hook up duck or other various bird calls to them!

 

http://youtube.com/watch?v=lZG0RS3mVBc&mode=related&search=

 

and I think atmospheric BOV's sound way better then recirc but thats just my opinion.

 

http://www.youtube.com/watch?v=Ldjwe5UUlwc&mode=related&search=

They are even COOLER when you hook up duck or other various bird calls to them!

 

http://youtube.com/watch?v=lZG0RS3mVBc&mode=related&search=

 

and I think atmospheric BOV's sound way better then recirc but thats just my opinion.

 

http://www.youtube.com/watch?v=Ldjwe5UUlwc&mode=related&search=

 

I think venting to the atmosphere screws with the MAF setup on our cars. But I don't know really, just though I read that and it makes sense. When the the valve vents the MAF would see lots of air moving through and deliver lots of fuel. But the air would not be going into the engine, so it would be really rich between shifts and pop alot.

I had some popping on my 86 when I first put a blowoff valve on it, but I was able to adjust it out between the TPS and the MAF itself (talking flapper door style pre 87). It really only popped if you were just barely on the gas... so step on it and you will be good . I also have a blowoff on my 88, it seems to be fine all by itself. It will pop (more like gurgle) if you just barely touch the throttle, but I think thats more to due with a faulty tps/idle switch or my lack of getting it adjusted perfect.

 

All in all you will probably not be unhappy in any circumstance recirc. or atmosphere and chances are your car idles rich already. Just my 2 cents.

 

Scott

i now run the stock wrx bov to the atmosphere. much better throttle response then recirced back into the intake or running compressor surge. it doesn't run rich either and gets about the same gas mileage.

BOV venting to atmosphere == RICE

 

Not my cup of tea to say the least, but I have already told you my thoughts on the subject Gloyale...

 

I will say this here.. the sound of a BOV venting truly angers the police, deep down in their heart and soul... The POLICE certainly seem to think that a BOV makes the car go MUCH faster, and your insurance rates may well reflect that in the future.

BOV venting to atmosphere == RICE

 

Not my cup of tea to say the least, but I have already told you my thoughts on the subject Gloyale...

 

I will say this here.. the sound of a BOV venting truly angers the police, deep down in their heart and soul... The POLICE certainly seem to think that a BOV makes the car go MUCH faster, and your insurance rates may well reflect that in the future.

i've never had problems with the BOV and police. i've actually had one case where the cop liked the sound.

how is venting it to the atmosphere rice?

i now run the stock wrx bov to the atmosphere. much better throttle response then recirced back into the intake or running compressor surge. it doesn't run rich either and gets about the same gas mileage.

 

Any air that goes through the maf sensor then does not go through engine, atmosheric dump, will make it run rich for a second. This is because the ecu has added fuel for this air but its no longer going to the engine. So the engine gets too much fuel (rich) after you close your throttle quick enough.

 

Main reason for a bov is once you get off the throttle less exhuast is being made so the turbo make less boost aswell, but a second before you got off it the turbo was losts of pressure. As higher pressure air flows toward low pressure air the boost made 1 second before getting off the throttle is trying to flow back towards the turbo instead of towards the engine. If this reverse air flow is sufficent it will slow the turbo impeller or in theory turn the impeller backwards. A bov is placed imbertween turbo and engine on the intake side. When the valve sees that there is less pressure in itself with reference to the intake manifold, it opens and dumps this air, which is about to flow backwards toward turbo. Dumping this air alows the turbo to be spinng faster between gear changes than if the air flowed back thru it and slowed it down.

 

I hope you can get what I am trying to say. So in theory a bov wont make more ponies but will allow the turbo to spool faster.

i've never had problems with the BOV and police. i've actually had one case where the cop liked the sound.

 

 

I knew someone had to chime in like this.. The police down in south florida certainly hate to hear that sound. That sound means someone's street racin', and they cant tolerate that, no no! I speak from firsthand experience in a friend's car, as well as general consensus among anyone who isnt living out of daddy's wallet down here.. if they are living out of daddy's wallet, then they don't mind if the BOV on the EVO that daddy bought them gets them a ticket that daddy has to pay and their insurance rates go up. Thats all.. and the LAST thing im trying to do is broadcast this image on anyone HERE.. I'm just commenting on the people I see running around in my town with loud BOVs...

 

I think I have already explained what makes me think of it as ricey, too.. In my mind, a few minor points in favor of recirculating bypass valve are more than enough to tip the balance. Once air gets metered by the MAF, the ECU WILL be injecting the amount of fuel needed for that air.. blowing it off is just like a vacuum leak; just a controlled and intermittent vacuum leak. routing it back into the pre-turbo side of the intake, anywhere between turbo and MAF, is the proper way to set it up. If you have proper engine management then you can engineer the system to understand that you are venting metered air to the atmosphere; in fact, MAP based systems (as opposed to MAF) don't even hesitate at this. However, on a MAF or AFM based EFI, dumping metered air means richening your mixture. Any stories of "I had no problems doing this.." are anecdotal evidence to say the least; when it comes to how the system on the car works, there is no question that a recirculating bypass valve is the only way to set it up properly.

To each their own! All I can say is that I currently own 3 GL-10 turbowagons, they each have a blowoff that vents to the atmosphere and all run just fine. They do run rich for a second, but it truly is minimal and that is a fact (based on LM-1 wideband). The above is true for pre 87 and 87+. You are right that our stories are anecdotal evidence, but as I recall, you have an N/A so you can't relate to us very well can you?

 

Scott

A turbo car, is a turbo car, is a turbo car;

 

Ask me about the Z-cars my family runs; and the SRT-4 that my buddy counts on me to keep running; and the SE-R 200SX the OTHER buddy counts on me to keep running; and the 240SX the OTHER other buddy counts on me to keep running...