Blow-by
07-05-2007, 01:49 AM
#1
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Blow-by
Last Sunday I was at the Seven lakes drive and was told that blue smoke was coming out the tail pipe on acceleration and at 14 psi of boost. My mechanic installed a catch can, which I was told would eliminate the smoke if it was blow-by. But smoke still comes out the tailpipe and the catch can has minimal amount of oil, maybe a teaspoon. Do you thik it's blow-by even though I have the catch can? TIA, Reno
07-05-2007, 07:46 AM
#3
What sort of catch-can is this?
I feel like a broken record but you must keep the vacuum circuit - we have free vacuum available because of our turbos, and some knuckleheads elliminate it!!
That kills me!
A whole industry of guys making vacuum pumps just to put negative pressure into theWET sump, and 951 guys rip it out
Anyway - what happens is, you can overload the turbocharger exhaust seals from a drain that is or can be somewhat obstructed.
Porsche wanted vacuum there - probably a good idea to keep this one.
I feel like a broken record but you must keep the vacuum circuit - we have free vacuum available because of our turbos, and some knuckleheads elliminate it!!
That kills me!
A whole industry of guys making vacuum pumps just to put negative pressure into theWET sump, and 951 guys rip it out
Anyway - what happens is, you can overload the turbocharger exhaust seals from a drain that is or can be somewhat obstructed.
Porsche wanted vacuum there - probably a good idea to keep this one.
07-05-2007, 08:03 AM
#5
Mornin' Ski
I have done both.
Drilling it I picked up condensation only everytime I started the car from cold.
Right now, my AOS is not drilled, and I pick up nothing, not even water - so I might open it a little.
I have done both.
Drilling it I picked up condensation only everytime I started the car from cold.
Right now, my AOS is not drilled, and I pick up nothing, not even water - so I might open it a little.
07-05-2007, 10:22 AM
#6
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Originally Posted by reno928s
Last Sunday I was at the Seven lakes drive and was told that blue smoke was coming out the tail pipe on acceleration and at 14 psi of boost. My mechanic installed a catch can, which I was told would eliminate the smoke if it was blow-by. But smoke still comes out the tailpipe and the catch can has minimal amount of oil, maybe a teaspoon. Do you thik it's blow-by even though I have the catch can? TIA, Reno
07-05-2007, 11:52 AM
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hosrom_951, Yes it only smokes under boost. It never smokes on start up or regular driving. Under hard driving I'll go through a quart every 350 to 400 miles.
special tool, it's the Lindsey catch can and my X mechanic installed it. ST can you explain in baby talk what the heck your saying with negative vacuum. That way I can look to see if my mechanic installed it correct. Thanks
special tool, it's the Lindsey catch can and my X mechanic installed it. ST can you explain in baby talk what the heck your saying with negative vacuum. That way I can look to see if my mechanic installed it correct. Thanks
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07-05-2007, 12:48 PM
#8
Well - I don't want to say bad things about 951 vendors, but I disagree with them on this.
The 951 likes to have the catch-can routed to the turbo intake - simple as that.
I have had many different can configurations and 6 different turbos on my car, and that's the way it is.
I have seen TWO cars with oil smoke (after boost at idle) now stop doing this after the vacuum was enabled again (the way the factory did it)
Maybe Rolex will offer some experience here.
The 951 likes to have the catch-can routed to the turbo intake - simple as that.
I have had many different can configurations and 6 different turbos on my car, and that's the way it is.
I have seen TWO cars with oil smoke (after boost at idle) now stop doing this after the vacuum was enabled again (the way the factory did it)
Maybe Rolex will offer some experience here.
07-05-2007, 01:08 PM
#9
Originally Posted by special tool
Well - I don't want to say bad things about 951 vendors, but I disagree with them on this.
The 951 likes to have the catch-can routed to the turbo intake - simple as that.
I have had many different can configurations and 6 different turbos on my car, and that's the way it is.
I have seen TWO cars with oil smoke (after boost at idle) now stop doing this after the vacuum was enabled again (the way the factory did it)
Maybe Rolex will offer some experience here.
The 951 likes to have the catch-can routed to the turbo intake - simple as that.
I have had many different can configurations and 6 different turbos on my car, and that's the way it is.
I have seen TWO cars with oil smoke (after boost at idle) now stop doing this after the vacuum was enabled again (the way the factory did it)
Maybe Rolex will offer some experience here.
07-05-2007, 01:14 PM
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Originally Posted by special tool
Mornin' Ski
I have done both.
Drilling it I picked up condensation only everytime I started the car from cold.
Right now, my AOS is not drilled, and I pick up nothing, not even water - so I might open it a little.
I have done both.
Drilling it I picked up condensation only everytime I started the car from cold.
Right now, my AOS is not drilled, and I pick up nothing, not even water - so I might open it a little.
07-05-2007, 03:09 PM
#12
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Originally Posted by LFA951
What if you have a MAF, then you can't reroute it...
07-05-2007, 04:03 PM
#14
Originally Posted by LFA951
Well, the LR pipe only has a port for the BOV and the Fuel vapor hose!!
yes - that is only the start of the trouble.
I think you should talk to Rolex.
07-05-2007, 04:04 PM
#15
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Originally Posted by LFA951
Well, the LR pipe only has a port for the BOV and the Fuel vapor hose!!