Whats better? Remote Crankcase Breather or..
10-13-2003, 09:34 AM
#16
Rennlist Member
Yes,
I still have my stock PCV tube hooked into the intake. I firmly believe that this is necessary to provide vacuum while under boost. My setup there is also unique. As someone who tracks my car alot, I did not like the partial throttle bucking and the surging when lifting throttle that was caused by the blow off valve recirculating to the intake. I have customized my blow off valve to dump to atmosphere also through a sump pump check valve with a spring (to prevent reverse flow), so the normal hook up to the intake pipe has been capped with a rubber end cap. My car is extremely smooth now, so I am sticking with it.
I still have my stock PCV tube hooked into the intake. I firmly believe that this is necessary to provide vacuum while under boost. My setup there is also unique. As someone who tracks my car alot, I did not like the partial throttle bucking and the surging when lifting throttle that was caused by the blow off valve recirculating to the intake. I have customized my blow off valve to dump to atmosphere also through a sump pump check valve with a spring (to prevent reverse flow), so the normal hook up to the intake pipe has been capped with a rubber end cap. My car is extremely smooth now, so I am sticking with it.
10-13-2003, 11:28 AM
#17
Rennlist Member
Tony, if you follow the line that goes from the outlet of the air/oil spearator back to the turbo inlet, there is a small check valve tee'd into the line just before the line connects to the steel pipe that runs adjacent to the turbo. I believe this is the factory's attempt at ensuring that the crankcase did not overpressure if the return to the turbo inlet got blocked somehow. Trouble is its a very small POS thing that needs about 5-10psi to check it.
Vic, I uses a similar set up to David but used a little JB weld epoxt to hold the top coil of my sprinkler spring inside the sump pump check valve. I have not got the filter yet but am not concerned as you will only ever vent out of the thing on not draw air into it.
Vic, I uses a similar set up to David but used a little JB weld epoxt to hold the top coil of my sprinkler spring inside the sump pump check valve. I have not got the filter yet but am not concerned as you will only ever vent out of the thing on not draw air into it.
10-13-2003, 12:01 PM
#18
Rennlist Junkie Forever
David Salama
The surging you are referring to is a direct result of reversion, and happens because the HR sensor gets screwed up when the air goes backwards through it... It's measuing that air running backwards through the sensor...which is why your car would go rich then lean....
Old problem.... with many different cures. Each with different degrees of sucess and difficulty.
The easy fix is to simply get a different style MAF sensor and have it calibrated to match your existing sensor.
The surging you are referring to is a direct result of reversion, and happens because the HR sensor gets screwed up when the air goes backwards through it... It's measuing that air running backwards through the sensor...which is why your car would go rich then lean....
Old problem.... with many different cures. Each with different degrees of sucess and difficulty.
The easy fix is to simply get a different style MAF sensor and have it calibrated to match your existing sensor.
10-13-2003, 12:40 PM
#20
Rennlist Member
IMHO.... I don't think there is any significant vacuum in front of the turbo inlet. If there was (1psi or more), it would only be an indication that the air filter/ air box was way to restrictive (not good for overall turbo efficiency).Porsche vented the crankcase fumes back to the inlet mainly for emissions. David, with your setup you'd still have to deal with the annoying oil in the intercooler,etc, wouldn't you? Unless you think there would be just alot less of it!
10-13-2003, 01:09 PM
#21
Rennlist Member
Yes, oil in the intercooler will still have to be addressed with a seprator on the vent line to the turbo, I am thinking of doing this next...once I can cure my damn mis fire......................
10-13-2003, 01:31 PM
#22
Rennlist Member
Turbotommy,
I do still have a small amount of oil in the hard pipes and intercooler, but I don't find that this is a problem and it never pools. In terms of a vacuum effect, that would be an interesting measurement in the intake. With that turbo spooled up and a K&N filter restricting inflow, I bet there is a pretty good vacuum created, but I don't have numbers. There has to be a pressure differential though because that is what draws air into the turbo in the first place. I do know that when I disconnected my PCV from the intake, I blew my oil dipstick out, so that tells me positive pressure is not being adequately vented without the added benefit from the intake suction or my custom check valve breather or both.
Tony,
I guess I do understand that the surging is also from the HR MAF, but with atmospheric blow off, it is no longer present, so no need to spend money on changing the sensor.
I do still have a small amount of oil in the hard pipes and intercooler, but I don't find that this is a problem and it never pools. In terms of a vacuum effect, that would be an interesting measurement in the intake. With that turbo spooled up and a K&N filter restricting inflow, I bet there is a pretty good vacuum created, but I don't have numbers. There has to be a pressure differential though because that is what draws air into the turbo in the first place. I do know that when I disconnected my PCV from the intake, I blew my oil dipstick out, so that tells me positive pressure is not being adequately vented without the added benefit from the intake suction or my custom check valve breather or both.
Tony,
I guess I do understand that the surging is also from the HR MAF, but with atmospheric blow off, it is no longer present, so no need to spend money on changing the sensor.
10-13-2003, 02:23 PM
#23
Rennlist Member
Hi David. You'd think that the crankcase wouldn't need that supposed vacuum in the inlet. Pressure always flows from the high side to the low. If pressure builds up in the crankcase it would immediately be relieved by a lower pressure area; therefore ambient conditions should be adequate (providing there are no blockages, of course). I am puzzled by the popping dipstick, though. There was a thread quit awhile ago on this but the author did not conclude a positive relation to lack of vacuumming. I'm wondering if because some of us slightly overfill our crankcases and together with high RPMs we have instantly high windage causing a temporary spike in crankcase pressure. Just a thought
12-28-2009, 02:36 PM
#24
Drive-by provocation guy
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Blast from the past thread.
Any updates on the innovative fabrications mentioned in this thread? Both the breather and BOV set ups.
I am researching breathers obvioulsy and this seems interersting as does David's BOV atm vent.
With the breathers, how much crank case pressure is being vented? Isn't bad to drop crankcase oil pressure to much or is this just for spikes in pressure?
Any updates on the innovative fabrications mentioned in this thread? Both the breather and BOV set ups.
I am researching breathers obvioulsy and this seems interersting as does David's BOV atm vent.
With the breathers, how much crank case pressure is being vented? Isn't bad to drop crankcase oil pressure to much or is this just for spikes in pressure?
