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 Post subject: bov
PostPosted: Tue Sep 07, 2010 1:07 am 
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Joined: Mon Aug 30, 2010 10:44 pm
Posts: 31
Location: seattle, wa
alright just picked up a greddy knockoff and i know where the factory bypass valve is under the air filter housing but i was wondering if i need to take off the factory bypass valve or just disconnect it. if i do need to disconnect it there are 2 other vaccum lines that run to it from a temp sensor what do i do with these?


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 Post subject: Re: bov
PostPosted: Tue Sep 07, 2010 2:23 pm 
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Joined: Wed Oct 04, 2006 3:03 pm
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Location: Calgary, AB, Canada
I think your looking at the secondary air parts. They are for emissions, it's the pipe that goes to the o2 housing, with the other end going to a hose that is routed under the intake manifold.

2g turbo cars, (g32b engine with TBI), did not come with a recirculation or blow off valve. What you hear is turbo surge.

If you add one make sure it recirculates.

[edit] you could also be looking at the oil catch can.

_________________
05 wrx wagon
99 Benz ML 320
91 eagle summit swapped - 6/4 bolt combo
94 Audi s4 - sold
88 Eagle Vista Turbo LX sedan, RIP


Last edited by j2dapo on Tue Sep 07, 2010 2:28 pm, edited 3 times in total.

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 Post subject: Re: bov
PostPosted: Tue Sep 07, 2010 2:24 pm 
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Location: Phoenix, AZ
I've never owned a C10, so I dunno about the other vacuum tubes, but I do know what the one that is connected to the Blow off valve/Recirc valve does. It connects between your intake side of your head and the throttle body (essentially it connects to your intake manifold), or the manifold pressure source on your throttle body(if you have one). Basically when you let go of the throttle, the throttle plate closes, causes a vacuum in the intake manifold from the engine that is still pulling in air, that vacuum pulls the air out of the vacuum line & the actuator, actuating the bov/recirc valve, releasing all the boost between the turbo and the throttle body. This process reduces the compressor surge on your turbo. Compressor surge is the act of the air slamming against the throttle plate, sending waves of pressure back to the turbo, which causes the turbo to rapidly decelerate. BTW this is equivalent to the rapid deceleration you feel when your body hits the pavement after you jump off a building. Not good for turbos!

So All in all BOV/Recirc valves keeps your turbo nice and spooled. It however does not regulate boost, that is the job of the waste gate.
I hope my little rant on BOV might give you a better understanding on how they work.
Also if you don't have a vacuum source a BOV/recirc valve shouldn't leak. I would cap off the recirc point anyways, in case the diaphragm is kinda old. Either that or remove it completely. You can also see if any boost leaks after you drive it.

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 Post subject: Re: bov
PostPosted: Tue Sep 07, 2010 2:25 pm 
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Now Drives a hybrid :(
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Location: Phoenix, AZ
Quote:
I think your looking at the secondary air parts. They are for emissions, it's the pipe that goes to the o2 housing, with the other end going to a hose that is routed under the intake manifold.

2g cars did not come with a recirculation or blow off valve. What you hear is turbo surge.

If you add one make sure it recirculates.
I did not know they didn't come with recirc/Blow off valves! That's nasty :o

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 Post subject: Re: bov
PostPosted: Tue Sep 07, 2010 3:34 pm 
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Joined: Fri Jul 22, 2005 2:02 am
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Location: rockford, IL
actually alot of OEM turbo car's didnt. even the mighty GMC syclone/typhoon's didnt have a stock one.


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 Post subject: Re: bov
PostPosted: Wed Sep 08, 2010 2:36 pm 
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Location: seattle, wa
actually i have had 17 turbocharged cars and i know for a fact that every turbocharged application has to have some fourm of bypass/recirculation valve, alot of the times they have some random name for it but all you gotta do is find a hose that runs to the non pressure side of the turbo that will be attached to a valve and about 80% that will be the bypass/recirculation valve. without a bypass/recirculation valve you would have a large amount of air that has no where to go so u will most likely keep blowing off your pressure side piping.
Quote:
actually alot of OEM turbo car's didnt. even the mighty GMC syclone/typhoon's didnt have a stock one.


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 Post subject: Re: bov
PostPosted: Wed Sep 08, 2010 10:16 pm 
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Some call me a god

Joined: Wed Oct 04, 2006 3:03 pm
Posts: 1134
Location: Calgary, AB, Canada
you may be correct about your car in particular, and my previous statement of no 2g turbo coming with is probably incorrect.

I should have said that all the 2g turbo csm's I've seen, here in Canada, did not have one. Also the manual for my car, and my car, an 1988, do not show one. Surge is not a big issue when you pushing 8 psi out of a hairdrier (aka td04-9b)

Post up some pics of your ride.

_________________
05 wrx wagon
99 Benz ML 320
91 eagle summit swapped - 6/4 bolt combo
94 Audi s4 - sold
88 Eagle Vista Turbo LX sedan, RIP


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 Post subject: Re: bov
PostPosted: Thu Sep 09, 2010 4:31 pm 
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Joined: Mon Aug 30, 2010 10:44 pm
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Location: seattle, wa
i will put some pics up so far from what i have seen mine is one of the most mint and clean 87 turbos that i have seen, its got 99k from the og owner with all service records from mitsu, every single paper that came with the car (og window sticker, all the original purchase paper work, the 87 mirage catalog that they ordered the car from) and it has the red and black turbo interior, body and interior are 9.85 outta 10 i just gotta wash her before i take some pics


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 Post subject: Re: bov
PostPosted: Sat Sep 11, 2010 1:25 pm 
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Spends Too Much Time Under The Hood

Joined: Fri Jul 22, 2005 2:02 am
Posts: 357
Location: rockford, IL
Quote:
actually i have had 17 turbocharged cars and i know for a fact that every turbocharged application has to have some fourm of bypass/recirculation valve
now instead of talking out of your ass, ACTUALLY DO SOME RESEARCH. ;)

but make sure you post back. just so people know that you like to post about shit you have no clue about. lol :lol: (wouldnt be a dick about it if you werent so cocky when being wrong)

and for the record i own 3 turbo cars right now, all running, and a turbo OHC liquid cooled 2 cyl lawn mower. ive owned well over a dozen turbo cars including buick t-types, and two original colt turbo's. and i currently own the only turbo FE3 swapped 626gt in the country. ;)

oyea, here's a forum for you to search. just so you can find what i said is correct faster, and post it for me. :supz: www.syty.net. thanks.


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