What to do with oil breather system with the supercharger
12-23-2002 | 09:28 PM
#17
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The breather setup on the early cars is really like a purge can with the filter inside so I'm trying this out...
It's a cheap ($9) 'APC' push on breather that I pushed into the oil cap. (I had to put a piece of tubing inside the rubber fitting to expand it to fit snuggly in the cap opening.)
After readjusting the AFM it actually seems to have made a little bit of a power increase - I had to turn down the idle too.
It's stinky though, it's mostly water vapor coming out, but also oil smell, which gets into the cabin at stoplights.
It's a cheap ($9) 'APC' push on breather that I pushed into the oil cap. (I had to put a piece of tubing inside the rubber fitting to expand it to fit snuggly in the cap opening.)
After readjusting the AFM it actually seems to have made a little bit of a power increase - I had to turn down the idle too.
It's stinky though, it's mostly water vapor coming out, but also oil smell, which gets into the cabin at stoplights.
12-24-2002 | 01:21 AM
#18
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From: Edmonton, Ab
I suspect that you are going to end up with some amount of "stink" if you vent the crank-case overboard, regardless of how you do it. <img src="graemlins/c.gif" border="0" alt="[ouch]" />
How about something of a rudimentary filter between the crank-case and a tap into the inlet side of the S/C. In piston aircraft, there is an aftermarket device that is designed to help keep the underside of the airplane clean(er) because they do vent the crank-case overboard, and usually spread "crud" across the bottom of the fuselage. This "air/oil separator" is quite effective, judging from the amount of "crud" that it catches from my Comanche's IO-540. I suppose it is a "vent can" of sorts, but has in/out plumbing that could be plumbed from one crank-case vent into the S/C inlet side. This ought to take care of the passive-side; and a PCV valve plumbed from the other vent into the normal intake manifold fitting would create the active-side. <img src="graemlins/yltype.gif" border="0" alt="[typing]" />
It might just smell better. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
How about something of a rudimentary filter between the crank-case and a tap into the inlet side of the S/C. In piston aircraft, there is an aftermarket device that is designed to help keep the underside of the airplane clean(er) because they do vent the crank-case overboard, and usually spread "crud" across the bottom of the fuselage. This "air/oil separator" is quite effective, judging from the amount of "crud" that it catches from my Comanche's IO-540. I suppose it is a "vent can" of sorts, but has in/out plumbing that could be plumbed from one crank-case vent into the S/C inlet side. This ought to take care of the passive-side; and a PCV valve plumbed from the other vent into the normal intake manifold fitting would create the active-side. <img src="graemlins/yltype.gif" border="0" alt="[typing]" />
It might just smell better. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
12-24-2002 | 03:08 AM
#19
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[quote]Originally posted by GoRideSno:
<strong>Venting it before the SC is not the problem. It is not a good idea on my system because the MAF is after the SC. The hot wire would be soon fouled by the excessive blow-by that many if not most 928s have</strong><hr></blockquote>
There is another issue besides the possibility of the oil fouling the MAF sensor wire. At least part of the blowby gasses are unburned air/fuel mixture. When it passed through the MAF sensor, the sensor would be measuring it as fresh air, and the LH computer mapping will adjust the injector pulse width based on that assumption of it being fresh air. Since there would already be some fuel in what's going through the MAF sensor then, the mapping will be providing a mixture that's too rich. It's basically the same as when some diagnostic procedures tell you to feed propane into the intake to richen the mixture when checking for things like proper oxygen sensor and closed loop operation. The oxygen sensor will detect the rich mixture and provide feedback that the LH computer will then use to lean out the mixture to what it should be. The oxygen sensor feedback adjustment by the LH computer is really just a "fine tuning", and is limited in the amount that the mixture can be adjusted. Will the range of fine tuning be enough to compensate for the fuel that's already in the blowby gasses that are entering the engine again? Maybe. Maybe not. It depends a lot on the particular car. That's one reason that the stock breather system is routed back into the engine after the MAF sensor.
Many supercharger installations have the MAF senor moved to the intake side of the supercharger. The blowby gasses are then routed into the system between the MAF and supercharger intake. That's the emissions legal way to do it. That's why at least some of the supercharger manufacturers will officially tell you it should be done that way. Getting their product considered an emissions legal modification wouldn't happen if they told you to route the breather system differently than back into the intake.
<strong>Venting it before the SC is not the problem. It is not a good idea on my system because the MAF is after the SC. The hot wire would be soon fouled by the excessive blow-by that many if not most 928s have</strong><hr></blockquote>
There is another issue besides the possibility of the oil fouling the MAF sensor wire. At least part of the blowby gasses are unburned air/fuel mixture. When it passed through the MAF sensor, the sensor would be measuring it as fresh air, and the LH computer mapping will adjust the injector pulse width based on that assumption of it being fresh air. Since there would already be some fuel in what's going through the MAF sensor then, the mapping will be providing a mixture that's too rich. It's basically the same as when some diagnostic procedures tell you to feed propane into the intake to richen the mixture when checking for things like proper oxygen sensor and closed loop operation. The oxygen sensor will detect the rich mixture and provide feedback that the LH computer will then use to lean out the mixture to what it should be. The oxygen sensor feedback adjustment by the LH computer is really just a "fine tuning", and is limited in the amount that the mixture can be adjusted. Will the range of fine tuning be enough to compensate for the fuel that's already in the blowby gasses that are entering the engine again? Maybe. Maybe not. It depends a lot on the particular car. That's one reason that the stock breather system is routed back into the engine after the MAF sensor.
Many supercharger installations have the MAF senor moved to the intake side of the supercharger. The blowby gasses are then routed into the system between the MAF and supercharger intake. That's the emissions legal way to do it. That's why at least some of the supercharger manufacturers will officially tell you it should be done that way. Getting their product considered an emissions legal modification wouldn't happen if they told you to route the breather system differently than back into the intake.
12-26-2002 | 08:29 PM
#20
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Found a different/cheaper (<$50) cool catch can...
<a href="http://www.jazproducts.com/index2.htm" target="_blank">Link: Jaz Products</a>
Some info <a href="http://cjsupra.kendra.com/PCV-Can.html" target="_blank">Link: Catch Can for Supra</a>
I find it hard to believe myself but my simple breather mod (see post/pic above) has actually made for some noticeable part-throttle grunt. The exhaust growl is deeper too...
Of course... YMMV
<a href="http://www.jazproducts.com/index2.htm" target="_blank">Link: Jaz Products</a>Some info <a href="http://cjsupra.kendra.com/PCV-Can.html" target="_blank">Link: Catch Can for Supra</a>
I find it hard to believe myself but my simple breather mod (see post/pic above) has actually made for some noticeable part-throttle grunt. The exhaust growl is deeper too...
Of course... YMMV
12-27-2002 | 05:38 AM
#21
Burning Brakes
Joined: Apr 2002
Posts: 881
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From: Denmark
Hello,
I made it like this – One extra oil separator designed to fit on the bolt for the engine lifting hook – This unit is in serial with the original and still connected to the vacuum inlet to the engine.
The reason for making this, I damaged two engines by detonations during long and fast 220 + km/h (140 + M/h) driving in Germany
PS: My engine is standard set-up
I made it like this – One extra oil separator designed to fit on the bolt for the engine lifting hook – This unit is in serial with the original and still connected to the vacuum inlet to the engine.
The reason for making this, I damaged two engines by detonations during long and fast 220 + km/h (140 + M/h) driving in Germany
PS: My engine is standard set-up
12-27-2002 | 04:48 PM
#23
Burning Brakes
Joined: Apr 2002
Posts: 881
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From: Denmark
Bredan,
Thank you!
It is connected to the original vacuum inlet - Only I routed the hoses from oil separator one -> oil separator two -> original vacuum inlet. I.e. it is not against the environmental law.
I also installed the GTS oil baffle from Devek, so with this and two oil separators I should be double secured – Like …..
Up to now I only got oil fumes in nr. 2, but I have not been driving in Germany since I installed the second oil separator.
The lid and the inside filter are from my spare engine
Due to limited space, it was a little tricky to make the design - I started building a model in cardboard and then following made the drawings and then the real things
The hoses are spare hoses from Thermostat->Return heating and Cyclone->Pan
If some of you are interested I can transmit my drawings.
Thank you!
It is connected to the original vacuum inlet - Only I routed the hoses from oil separator one -> oil separator two -> original vacuum inlet. I.e. it is not against the environmental law.
I also installed the GTS oil baffle from Devek, so with this and two oil separators I should be double secured – Like …..
Up to now I only got oil fumes in nr. 2, but I have not been driving in Germany since I installed the second oil separator.
The lid and the inside filter are from my spare engine
Due to limited space, it was a little tricky to make the design - I started building a model in cardboard and then following made the drawings and then the real things
The hoses are spare hoses from Thermostat->Return heating and Cyclone->Pan
If some of you are interested I can transmit my drawings.
