BOV on an automatic car?

[Tim_K]

My 89 Spirit 2.5 Turbo has an automatic transmission, so once I start building it beyond 200 hp, will I see any gains from a better than stock BOV?

Should I have it vent outside the air box, or leave it as it is?

And how much boost can a stock BOV hold reliably?

[3Bar_Mopar]

Quote:

Originally posted by Tim_K My 89 Spirit 2.5 Turbo has an automatic transmission, so once I start building it beyond 200 hp, will I see any gains from a better than stock BOV? Should I have it vent outside the air box, or leave it as it is? And how much boost can a stock BOV hold reliably?

You won't see "gains", but it won't leak boost, so I guess you may see a gain because of non-leaking boost.

Keeping it outside the airbox or not is up to you, although venting back into the intake (keeping it the airbox) tract will help keep the turbo spooled when you lift.

I think a stock BOV will hold 14 PSI max. Mine held 18+ every day (who knows how long that would've lasted?!?lol), but I've seen them leak at 12 before...

[TurboMinivan]

Quote:

Originally posted by Tim_K My 89 Spirit 2.5 Turbo has an automatic transmission, so once I start building it beyond 200 hp, will I see any gains from a better than stock BOV?

Depends what you mean by gains. You'll definitely see benefits, and those are always... well, beneficial.

Food for thought: when I first ditched the airbox in Clifford, I mounted a stock BOV in the upper intercooler pipe and let it vent to atmosphere. The thing would still surge after lifting the throttle. At the time there had just been a holy war online about if you should mount the BOV in the upper or lower intercooler hose, so I thought I'd test the system: I mounted a second stock BOV, this one in the lower hose. The van still surged on liftoff. Frustrated, I bought a first gen Talon valve and put it on the upper hose in place of the original stock BOV. Instantly, all my compressor surge was completely gone. Curious, I then removed the second stock BOV, leaving just the Talon valve in place. There was still no surge at all--none, nada, zip, zilch, zero.

<subtle hint>
I highly recommend a first gen Talon valve rather than a stock Mopar valve.
</subtle hint>

Quote:

Should I have it vent outside the air box, or leave it as it is?

This, too, can be a delicate subject--there are arguments both ways. In my mind, the entire purpose of the BOV is to prevent compressor surge by evacuating air as rapidly as possible. Therefore, I decided to let my valve dump air as rapidly as possible--by venting directly to atmosphere. (This method also means your engine is not "reingesting" air which was previously heated by the turbo, which was also a plus in my opinion.)

[3Bar_Mopar]

I had to add, that Dempsey reminded me that my van (the whole week I got to drive it) surged with the stock BOV, I forgot completely until this post. I suggest upgrading to a Talon or something better. I never had the surge problem on my Daytona (5 speed and 18+ PSI), but for some reason it's there on the van (10 PSI).

Quote:

Originally posted by TurboMinivan Depends what you mean by gains. You'll definitely see benefits, and those are always... well, beneficial. Food for thought: when I first ditched the airbox in Clifford, I mounted a stock BOV in the upper intercooler pipe and let it vent to atmosphere. The thing would still surge after lifting the throttle. At the time there had just been a holy war online about if you should mount the BOV in the upper or lower intercooler hose, so I thought I'd test the system: I mounted a second stock BOV, this one in the lower hose. The van still surged on liftoff. Frustrated, I bought a first gen Talon valve and put it on the upper hose in place of the original stock BOV. Instantly, all my compressor surge was completely gone. Curious, I then removed the second stock BOV, leaving just the Talon valve in place. There was still no surge at all--none, nada, zip, zilch, zero. <subtle hint> I highly recommend a first gen Talon valve rather than a stock Mopar valve. </subtle hint> This, too, can be a delicate subject--there are arguments both ways. In my mind, the entire purpose of the BOV is to prevent compressor surge by evacuating air as rapidly as possible. Therefore, I decided to let my valve dump air as rapidly as possible--by venting directly to atmosphere. (This method also means your engine is not "reingesting" air which was previously heated by the turbo, which was also a plus in my opinion.)

[Orangetona]

Well I have 2 stock BOVs and had them range from 5psi to 14psi and both have held just fine, but that doesnt mean anything. So just up it and see what happens lol.

[OmniGuy123]

If you mean gains in the 1/4mi. sense of teh term, no. The Grand National guys dont run them, and in an automatic I would just get one that holds the ammount of boost that you are running, and call it a day.

[Chadxton]

I had the impression a BOV should be used for boost blow-off regardless of the transmission type. Compressor surge is not nice to a turbo in either case.

[OmniGuy123]

Quote:

Originally posted by Chadxton I had the impression a BOV should be used for boost blow-off regardless of the transmission type. Compressor surge is not nice to a turbo in either case.

True, but with an automatic you will not expericence surge as much due to the fact that you dont let off the gas to shift. I agree that the surge will induce some wear and tare on the turbo, but like I say, the GN guys have a whole lot of miles on their turbos with no BOV.

[TBird232ci]

regardless, as long as a BOV doesnt leak, it will do no harm

[Stratman]

Quote:

Originally posted by TurboMinivan Depends what you mean by gains. You'll definitely see benefits, and those are always... well, beneficial. Frustrated, I bought a first gen Talon valve and put it on the upper hose in place of the original stock BOV. Instantly, all my compressor surge was completely gone. There was still no surge at all--none, nada, zip, zilch, zero. <subtle hint> I highly recommend a first gen Talon valve rather than a stock Mopar valve. </subtle hint>

Hi Dempsey,
How much boost were you pushing through the Talon valve? Did you modify it?
I just aquired one already on a pipe and didn't think it will hold 25 psi without modifiction.

[TurboMinivan]

Quote:

Originally posted by Stratman Hi Dempsey, How much boost were you pushing through the Talon valve? Did you modify it?

I've run 19-20 psi for extended periods (read: measured in years) and this puppy has held up fabulously. It is completely unmodified. To keep it from leaking, I did the Gus Mahon "build your own vacuum circuit" trick... and it works great.

I love it when the DSM crowd tosses these valves "because they leak." Say, can I carry it to the dumpster for you?

[Stratman]

Quote:

Originally posted by TurboMinivan To keep it from leaking, I did the Gus Mahon "build your own vacuum circuit" trick... and it works great.

Thanks Dempsey,

Where can I find the vacuum circuit info and how does it connect?

Thank for any info.

[TBird232ci]

http://www.gusmahon.org/html/Talon%20BOV.htm

the picture at the bottom of the page

[Casper]

First let me state that I am an AVID supporter and user of the DSM BOV.

With that being said, I do have to comment on the stock BOV. Let's remember that there are two types:

The pre-90 ones, which are near useless.

The '90 and later models, which are much better. Are they as good as a DSM, heavens no! They are much larger than their predecessor though and will eliminate surging. I ran 14psi for almost a year with the stock airbox/BOV in my Spirit. I installed Gus' vacuum circuit and had NO trouble whatsoever. The BOV diaphragm is still intact.

And for the bling-bling crowd, it does have a nice sound if you use a K&N filter...

FTR, I believe Dempsey is referring to the 3rd, 4th, 5th and 6th pictures on the page TBird232ci linked. As Gus mentions, Gary has a similar method for those using the flange.

The circuit for extending the life of stock, or Bosch BOV's is the last picture on the page.

[gti_7]

Ahhh, when did chrysler start putting factory bovs in their cars? i searched everywhere on my '88 lancer shelby and havent found one!

also..
could someone please explain this thing about having the bov IN the airbox? how does this work? and what are its advantages?

ive been pondering upper or lower IC piping myself.. and not sure which is better or worse.. perhaps this "in air box" idea would solve my question.

thanks
bernard