Bov

[camwfo]

what are you guys using for blow off valves with mass air cars?

[kenmosher]

Most don't ... no real need with an automatic.

[camwfo]

I hear the wheel in my friends car shuttering when he gets off the throttle under boost. Im a turbo mustang guy but I would assume the principle stands ford or buick. I know I have to run one on my car and its an automatic. I know some of the valves stay open and let unmetered air in motor. I was wondering what most GN guys were doing. I know they dont come with them stock but they dont run that much boost stock.

[Keller]

I know they dont come with them stock but they dont run that much boost stock.
Funny. I thought 15 PSI (1 bar), the stock amount, was considered a fair bit of boost.

Again, few if any cars run them. With a hard shifting automatic, there is no need to let the pressure bleed off between shifts. And on a slow down, proper modulation of your right foot prevents "compressor slam".

[kenmosher]

Probably no real harm to having a BOV, but also not a necessity.

Even though you might hear the "chuffle" (and you do on the stock car as well, it's just muffled by the air cleaner assembly ... gets much louder with a CAI), there are many cars out there with more than 100K on the stock turbo with no problems. It isn't a big deal on these cars, it seems.

I have never run one on my car in all these years with all sorts of high boost and bigger turbo. I've never had a problem with the turbo (I seem to be able to break almost everything else though! :winkgrin: ), other than a TA62 that just plain had balance problems.

Again, wouldn't hurt anything, but no clear advantage to one either.

[camwfo]

ool...thank for the info

[PaCemkr86]

im running the big HKS unit and have used the greddy TYPE R..
its works , i like it

[derek]

Funny. I thought 15 PSI (1 bar), the stock amount, was considered a fair bit of boost.

Again, few if any cars run them. With a hard shifting automatic, there is no need to let the pressure bleed off between shifts. And on a slow down, proper modulation of your right foot prevents "compressor slam".

I try to exercise this philosophy with about 35% success.I'm also considering a BOV because that flutter sound just makes me cringe and I think a BOV to atmosphere with a horn would sound wicked.

[Keller]

That sound should make you cringe, as it isn't good for the turbo.

In the early years that I had my car, and when I first had an open elemnet filter on it, I sometimes found that happening on the street after a quick burst of acceleration. After learning what it was and what it meant, I started pulling my foot back off the gas less abruptly

As far as a blow off valve "sounding cool"...I'd rather anyone around be looking at my rear end in the distance, not listening to to a blow off valve. I put this one in the "rice" category. Note the origin of manufacture for many of them, and how they declare that theirs make more noise than the competition, etc. Too much toy factor.

Sorry, not for me. :nope:

[PaCemkr86]

i agree with you Keller, but i had no luck finding one, that wasnt mad in Japan.
I didnt install mine for the sound, just the function.
And i have had NO problems with it blowing off to the the atmosphere
with the DEFCO function in the ecm.. so there is no need to pipe it back into the air intake

[Keller]

A followup:

A local clubmember has been chasing some odd idle behavior with his '86 T-Type. The idle had been unstable for some time. Initially, problems where traced to a bad MAF. That was replaced with a LT1/Translator Plus. However, no improvement. He has continued to try a lot of simple things: heated O2, plugs, checking for leaks, PVC, etc. No improvement.

I worked with him to chase it down last night. The problem? A leaking blow off valve on the side of the intercooler. The integrator and block learn numbers were in the toilet. I sensed some airflow coming from the area of the valve. The car's owner forced it closed, which sent the integrator numbers from 90 to 150, and killed the car.

He's going to try to rebuild it and make it work. My advice was to just cut out a block off plate, bolt that on, and be done with it.

[PaCemkr86]

FYI
If it has an adjustment screw with a lock nut.
Make sure you seal the threads that go into the BOV with teflon paste or tape
Ive seen 90% of these leak right out of the box new.

[buddiiee]

It makes no difference where your bov is made... lol. and yes, letting off the throttle does hurt your turbo I don't care what anyone says,,and it's never a good idea.. You can only let off the throttle so slow. I let off mine, and still get compressor slam regardless.. a LOT of local TR's run BOV's. More than not. They exist for a reason, manual or automatic. True, maybe you can run your car for years without one, but why take a chance? I wouldn't. I agree, most of the young'uns like them cuz they're loud, so there is a 'toy factor' involved. Those are the loud ones though. Just get the quietest you can find. That's what I'm going to do...

[PaCemkr86]

im using the GREDDY type R

[buddiiee]

and how is that greddy workin for ya so far.
i hear lot of good stuff about greddy and hks. all i know is, i cannot for the life of me let off my throttle slow enough, to stop the sound of compressor slam. unless you drive with both feet, and start applying the brakes a little sooner than normal, THEN start slowly lettin off the gas, that would help a bit (which in turn, would decrease the life of your brake pads a bit) you cant slow down quick enough in moderate to high traffic, if you spool that turbo, then have to hit the brakes again. if you use one foot, you gotta let off that throttle too quick. its unavoidable. i cringe at the sound as well. which is why im going to try either that greddy, or an hks. how loud is your greddy. i want mine as quiet as possible. im assuming, that if you vent it back into the system, it will be a tad quieter?

[PaCemkr86]

the greddy type R and HKS ssqv seem to work well.
The whoosh sound aint any louder then the sneezing sound they make without a bov

[PaCemkr86]

http://www.gnttype.org/forums/showthread.php?t=3884&page=2&highlight=blow+valve

some people say you dont need a bov, some do.
I have one, it works,
I like it and have no issues with mine.

[Street Surgeon]

You don't have to use one, but using one WILL increase the lifespan of your turbo since you'll be relieving the pressure inbetween shifts (yes it will still help EVEN on an automatic equipped vehicle) and thus preventing compressor surge (the chuffle sound you hear). You say your vehicles run mass air sensors, so I would choose one that can or does recirculate the air blown off to any point in the intake between the mass air sensor, and the turbo itself. That'll keep the air it already accounted for in the system, and prevent your motor from running a lil rich inbetween shifts. When choosing one, also make sure it can handle the amount of boost you're throwing at it.

-Cory

[Ormand]

The "chuffle" sound is not exactly surge. Surge is the compressor blades stalling when the compressor is called to provide more boost than it can, at flow rates lower than the compressor curve will allow. Basically, it means that the compressor is too big for the engine, at least at the surge condition, which is usually part throttle. The chuffle may reduce compressor life, but my turbo has almost 200,000 miles on it, and there are a lot of others with a of miles. The BOV is probably of more benefit when a bigger turbo is used, with higher boost.