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Who is using exhaust to pull crankcase vacuum?

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Old 08-04-2008, 11:23 AM
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Originally Posted by Stoichiometric
If you use the inlet of the turbo you will potentially draw oil into the intake. If it works out on the exhaust side that seems like the way to go.
That's what I'm thinking too. I just finished reading that other thread, and it looks like TurboGibbs tried the scavenging system as well, but once he got into boost it was actually pressurizing his crankcase. Maybe too much backpressure in the downpipe? He had a 3", I have a 3.5".

What I'm thinking is using the kit I pictured above and using BOTH fittings, running one to each valve cover through the baffled breathers that come with the kit. Then I can route my LS6 valley cover through a catch can and into the inlet side of the turbo (or just through a filter breather). As long as I don't pressurize the crankcase I would think that this would work fine....I'll just have to hook my boost gauge up to the crankcase the first couple times out and see whether or not it's building pressure.
Old 08-04-2008, 11:24 AM
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Originally Posted by Stoichiometric
If you ran one small hose with a check valve to the inlet of the turbo you would have filtered air for the crankcase. The check valve would allow flow into the crankcase only and prevent oil/air from getting pulled through the turbo.
That's a good idea too...would probably run that to the LS6 valley cover.
Old 08-04-2008, 11:26 AM
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A lot of the guys running these have open downpipes or open headers. I'm not sure if they work as well with mufflers in the exhaust.
Old 08-04-2008, 11:38 AM
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One of these days I will have a boost-actuated cutout coming off my downpipe, so it will be equivalent to having an open DP. ***coughKYLEcough***
Old 08-04-2008, 11:54 AM
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Originally Posted by Stoichiometric
A lot of the guys running these have open downpipes or open headers. I'm not sure if they work as well with mufflers in the exhaust.
I forgot there is also a check valve in the venturi port to keep exhaust backpressure from pressurizing the crankcase. I wonder if the setup TurboGibbs was using didn't have a check valve in it.
Old 08-04-2008, 12:27 PM
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I read somewhere that some guys were running a hose/tube farther down stream, towards the end of the tailpipe, exhaust velocity would be lower... They drilled a hole in the pipe and mounted the tube diagonally, facing the end of the tail pipe, so it would actually suck, instead of forcing exhaust back into the tube....
Old 08-04-2008, 12:30 PM
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Lower velocity would give less of the venturi effect I would think, which is the opposite of what you want in a setup like this.
Old 08-04-2008, 12:38 PM
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I think Parish tried the same thing with less than favorble results. Good luck though. Here is a link to his thread.

https://www.performancetrucks.net/fo...0&pp=40&page=7
Old 08-04-2008, 12:42 PM
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Originally Posted by thunder550
Lower velocity would give less of the venturi effect I would think, which is the opposite of what you want in a setup like this.
Perhaps, but like you said, you don't want too much or worse boost, thus the reason for placing it further down stream... The amount of exhaust you probably moving IMO it would more than enough... The best way would be to put a couple of probes in your exhaust and messure the vacuum being pulled at each spot, and also measure any boost, before commiting to a particular location...
Old 08-04-2008, 12:51 PM
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Originally Posted by OLD BULL
I think Parish tried the same thing with less than favorble results. Good luck though. Here is a link to his thread.

https://www.performancetrucks.net/fo...0&pp=40&page=7
His initial results with it were good, he talked about them in the ls1tech thread I linked to above. I never saw any follow-up though. I sent him a link to this thread in a PM so hopefully he will come in here and share his results.

Originally Posted by BlackGMC
Perhaps, but like you said, you don't want too much or worse boost, thus the reason for placing it further down stream... The amount of exhaust you probably moving IMO it would more than enough... The best way would be to put a couple of probes in your exhaust and messure the vacuum being pulled at each spot, and also measure any boost, before commiting to a particular location...
Velocity is good, pressure is bad. I think that's what you're getting at.


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