Air/oil separator

I am interested to hear from anyone who has the antisplat unit WITHOUT the vacuum to the exhaust (i.e. drain back to the sump). My objective is to reduce oil consumption (in addition to cleaning the belly). Right now, I am using about a quart per 5 hours and am convinced most is going overboard via the breather, even keeping the oil level in the range of 7 qt. It seems in principle the vacuum system would, if anything, increase the oil going out the breather system. Can anyone report whether they have significantly reduced oil consumption with the non-vacuum intallation?

I use an ASA separator on my 6 without any vacuum and it works well. However, it is not a panacea and still get trace amounts of oil on the belly, just a lot less than without a breather. I burn a qt in 10-15 hours.

1 qt in five hours is a lot and way too much for a separator to deal with. Adding vacuum may keep some or a lot of that oil off the belly, but it will do nothing to reduce the amount of oil spit out of the engine . The separator captures a bit and puts it back in the sump, but at your level of blowby there is no way to reduce the oil burn other than new rings/hone or a top overhaul.

Larry

bob888 said:

I am interested to hear from anyone who has the antisplat unit WITHOUT the vacuum to the exhaust (i.e. drain back to the sump).

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The separator can will return oil to the sump with or without a vacuum tap to the exhaust. They are separate functions.

My objective is to reduce oil consumption (in addition to cleaning the belly). Right now, I am using about a quart per 5 hours and am convinced most is going overboard via the breather, even keeping the oil level in the range of 7 qt.

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Oil leaves the engine three ways, (1) leakage, (2) past the rings and valve guides into the combustion chamber, and/or (3) via the crankcase breather. Can you tell us why you are convinced most of your oil loss is via the breather? Leaks are fairly obvious, but determining the relative quantity of the other two paths requires some investigation.

It seems in principle the vacuum system would, if anything, increase the oil going out the breather system.

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The oil, having a very low vapor pressure, is in an aerosol state, tiny liquid droplets suspended in crankcase blowby gasses. Reducing the density of the blowby gas reduces its ability to suspend droplets. A significant reduction in density (i.e. an effective crankcase vacuum system) thus reduces the quantity of oil being carried along in the crankcase gasses exiting the breather port.

Can anyone report whether they have significantly reduced oil consumption with the non-vacuum intallation?

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There are numerous separator systems on the market, with and without vacuum. They all work, more or less.

I am now using the ASA separator without the exhaust connection. I had the exhaust connection at one point, but disconnected it due to the build up of material in the exhaust port. I installed the system because I was using a quart every 8 hours. With the exhaust connection, I had trace amounts of oil on the belly and my consumption was around a quart every 15 hours. Without the connection to the exhaust, I am using a quart every 12 hours. Any level in the sump over 8 qts goes out the breather.

Responding to Danh re why loss seems to be via breather...mainly circumstantial. Plugs clean and exhaust system also. Lot of oil on belly.

Newbie question, is there any difference between the ASA air/oil seperator and the half raven system? Is the ASA appropriate for gentleman aerobatics?

I have the exhaust connection on the 7 I just purchased. Was warned to clean out the "saddle" every oil change. Didn't make it to the first one. Had an RPM drop like when you're running a tank dry that that was only a couple seconds in duration. Landed and noticed the normally clean belly and nose pant had some oil. Pulled cowl and did an oil change (my first on this AC) at 34 hours TACH. have image of the coked up saddle near 100% occluded. Am guessing it was for a split second, and dispelled oil around the clamps.

Just checked and there is now a "relief" valve that is new available to correct this (I was planning on cleaning it out every 25 tach hours).

Daniel, given this was your first oil change, it's possible that it wasn't cleaned at the last...unless the owner was doing 25 hour changes.

Where is that tap mounted on the exhaust system?

Also would like to know the answer to this question

Av8rRob said:

Newbie question, is there any difference between the ASA air/oil seperator and the half raven system? Is the ASA appropriate for gentleman aerobatics?

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Also interested in this question. Does anyone here have the technical expertise to answer?

I'm getting tired of having a belly full of oil after a not so stellar aerobatic maneuver, but I don't want to install a full inverted system.

Av8rRob said:

Newbie question, is there any difference between the ASA air/oil seperator and the half raven system? Is the ASA appropriate for gentleman aerobatics?

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Rob,
Two completely different systems, one is not a substitute for the other