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04-25-2014, 10:11 PM
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Join Date: Feb 2006
Location: Valley Forge, Pa
Posts: 636
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Quote:
Originally Posted by alpinelakespilot2000
Just got this article about oil separators in a Mike Busch newsletter I regularly receive. Seems he doesn't like them. Coincidentally, I happen to have an un-installed anti-splat kit ready to get put on. Hmm... Anyone know if the Anti-Splat ones mitigate any of the problems he mentions?
http://us5.campaign-archive1.com/?u=...7&e=1db3de8610
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Hi Steve,
If you change your mind and want to sell,please let me know.
RHill
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04-26-2014, 12:15 AM
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Join Date: Jan 2005
Location: NC25
Posts: 3,508
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Quote:
Originally Posted by N941WR
I'm in the process of writing an article regarding air / oil separators for publication in a future issue of KitPlanes.
My research indicates that there are as many opinions on using an air oil separator as there are people.
What I'm struggling with is finding true facts on if they are a good or bad thing.
Pouring a bunch of stuff on the ground doesn't neccissarly mean anything and based on the design of the separator, that water (?) could be burned off, captured, or returned to the engine.
One person I interviewed mentioned that there are a number of certified airplanes with separators installed at the factor and there are STC's to retrofit them. If they were so bad, why would this be allowed? - Interesting point.
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I am one person that has run an oil separator that dumps back into the engine for more than 16-years. After 2,200 hours, I pulled the Superior Cylinders that I had as the valve guides were worn out. The cylinders still had the crosshatch and standard value choke in the barrel. I now have ECI cylinders. The head on one of the Superior Investment Cast cylinders had a crack around the valve seat that leaked between the seat and head. The cam looked good. I now have 2,850 hours on the engine. I fall in the category that no issues have been found or proved in my use of the Aircraft Spruce Homebuilders oil separator after 2,850 flying hours. I used AeroShell 15W-50 most of the first 2,200 hours. Have used Phillips X/C 20-50 almost exclusively since going to the ECI (steel) Titan cylinders.
BTW, the engine I have was made in 1961 and now has total time of over 5,700 hours. It had a wet vacuum pump that used an oil separator that put the waste oil from the wet vacuum pump back into the engine when it was removed from a certificated aircraft. This is not the same thing as the crankcase vent that now goes into the inexpensive Aircraft Spruce Homebuilders special oil separator.
__________________
Gary A. Sobek
NC25 RV-6 Flying
3,400+ hours
Where is N157GS
Building RV-8 S/N: 80012
To most people, the sky is the limit.
To those who love aviation, the sky is home.
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04-26-2014, 05:49 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by alpinelakespilot2000
Just got this article about oil separators in a Mike Busch newsletter I regularly receive. Seems he doesn't like them.
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The breather air is quite hot. The three main constituents are combustion gas, oil droplets, and water vapor. The combustion gas and water vapor can be thought of as hot damp air, while the oil remains in a liquid state as small, suspended droplets.
If water is being sent back to the crankcase sump, the separator system is acting as a condenser, lowering air temperature enough to condense the water vapor to the liquid state. Only then can it return to the sump with the oil droplets, which were separated from the air by mechanical means.
If breather air is kept warm, the water vapor goes straight out the exit to the exhaust reed valve, or directly overboard in the case of no attempt at case evacuation.
Want to know if your Anti-Splat separator installation is condensing any significant quantity of water? Disconnect the drainback hose at the engine oil return port. Plug the engine return port. Stick the hose into an old oil bottle and tie the bottle to the engine mount. Go fly 10 hours and then check the bottle. Report back here.
That would be data. One measurement is worth 100 opinions.
I was talking with Bill the other day about separators. To really know the truth, we need a subject engine that has been on oil analysis for a while, say 200 hours, before having had a separator added to its breather. Run another 200 hours of with the separator, compare the printouts, know the facts.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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04-26-2014, 06:44 AM
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Join Date: Apr 2012
Location: Tampa (BKV)
Posts: 926
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Mike Busch knows more about engines than I'll ever know. I can admit that. But, in the end he is a human with opinions and preconceptions like the rest of us. With this one, at present, I disagree. We shall see in a couple thousand hours if I change my opinion.
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RV-8 Flying
1,235th flying RV8
SARL Race#95
SnF Homebuilt Judge
2015 Sun n Fun Kit Built Reserve Grand Champion
2015 Oshkosh Kit Built Champion
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2014 Oshkosh Outstanding Workmanship Award
Broken Warrior of the Jarhead Clan
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04-26-2014, 07:54 AM
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Join Date: Jun 2006
Location: Freericksburg, VA
Posts: 624
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Quote:
Originally Posted by DanH
That would be data. One measurement is worth 100 opinions.
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If only we could get you to call out the clowns in DC who prattle on with nothing but conviction to back their assertions....
__________________
Richard Bibb
RV-4 N144KT
Fredericksburg, VA
KEZF
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04-26-2014, 07:02 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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Quote:
Originally Posted by DanH
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Want to know if your Anti-Splat separator installation is condensing any significant quantity of water? Disconnect the drainback hose at the engine oil return port. Plug the engine return port. Stick the hose into an old oil bottle and tie the bottle to the engine mount. Go fly 10 hours and then check the bottle. Report back here.
That would be data. One measurement is worth 100 opinions.
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Exactly whag I'm working on.
I'll let everyone know when the article runs.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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04-26-2014, 07:55 PM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by N941WR
Exactly whag I'm working on.
I'll let everyone know when the article runs.
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Bill, As you are gathering evidence. Crankcase vacuum, say over about 5" of water, has the potential to pull unfiltered air into the engine. That might be evidenced by increased silicon in the oil sample analysis. Be careful, though, as a poor air filter or holes bypassing the filter will also have increased silicon as the air allows this to stick to the cylinder walls then get washed down. It does not take much in PPM to be a problem. That is probably the only durability issue with crankcase vacuum. Aircraft operate in a different environment that industrial engines and although the same principles apply, quantification of those principles and results differ. It may not be an issue for our birds. Just something to note as you are pursuing information for your article. BTW, I just subscribed to Kitplanes and look forward to your article.
__________________
Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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04-27-2014, 06:47 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by BillL
Bill, As you are gathering evidence. Crankcase vacuum, say over about 5" of water, has the potential to pull unfiltered air into the engine.
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The air (and silicon dirt) would have to work its way past some engine seal, but it's a valid proposal. See, another good reason to hope somebody here can present oil analysis results eventually.
Quote:
Originally Posted by N941WR
Exactly what I'm working on.
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Bill, BillL's note also offers a good reminder regarding your current test....seal the catch bottle to the hose if you're running an evacuator tap with the separator. If you don't, it will pull air into the system at the neck of the catch bottle and route it to the evacuator tap on the exhaust. That flow will oppose normal drainage to the catch bottle and skew the test results.
Everyone...don't get confused about discussion of vacuum in the context of Busch's objections. We are not all running identical systems. There are many choices in use:
1. Breather to overboard drain point....the usual way.
2. Breather to separator, air outlet to overboard, liquid output to catch bottle. Reduction in belly mess.
3. Breather to separator, air outlet to overboard, liquid output to engine sump. Reduction in belly mess and overall oil consumption.
4. Breather to separator, air outlet to exhaust via a reed valve, liquid output to sealed catch bottle. Reduction in case pressure and overall belly mess.
5. Breather to separator, air outlet to exhaust via a reed valve, liquid output to engine sump. Reduction in case pressure, overall belly mess, and oil consumption.
Only (4) and (5) reduce case pressure, i.e. pull a vacuum in the case. The Busch video example was probably a (2).
BTW, systems with a case evacuator (4 & 5, reed valve to the exhaust) reduce the temperature at which water vapor would condense. If you assume a pressure reduction of 3"Hg (it varies, but that's a fair average), the boiling point reduction would be a bit more than 5F. Put another way, running a case evacuator with your separator reduces the chance of condensing water and returning to the sump.
If your separator/evacuator system is operating in a hot area of the engine compartment, you further reduce the chance of condensing water. Conversely, if your GA clunker has a big leak in the rear baffle flap seal so the separator is operating in a jet of nice cool air, yep, you have a condenser.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 04-27-2014 at 06:50 AM.
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04-28-2014, 05:05 PM
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Join Date: Aug 2009
Location: Goodyear, Arizona
Posts: 877
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That's a useful post Dan, thanks very much.
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Karl, Goodyear, Arizona (KGYR) ATP, CFII
RV-14A, Flying
Extra 330LX, Flying
RV-8, Sold
RV-7, Sold
Bearhawk 4-Place, Sold
=VAF= donor 2020
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05-02-2014, 06:04 PM
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Join Date: Apr 2005
Location: Indepenence, Oregon
Posts: 342
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Just a data point. My -10 has the AntiSplat with vacuum valve mounted as high as it can go and drains to the motor. First dozen hours, had oil on the belly, mostly because I was adding and then watching level to try and find its "natural" level. (About 9.75 quarts.). Now I have a clean belly.
Here is some real data. I have an extra thermocouple in the engine compartment and the fues. I put it on the separator. Runs between 120 and 130 degrees F. Engine has a tight plenum, so there is no extra air except one blast tube on the mag which is on the other side of the compartment.
FYI, hot tunnel data. Right between the air valves it runs 220 to 240 degrees. My tunnel, after adding reflective insulation outside, foam inside and baffle material between the valves and firewall is still about 100. -120. Before it went over 200 with the rear heat on, about 180 with heat off. Still want more improvement, ADSB and transponder are in the tunnel, up front.
__________________
Bruce Patton
Rans S-20 Raven 796S flying since 2019 (slowly)
RV-6A 596S flying since '99 (Sold)
HP-18 5596S flying since '89
RV-10 996S flying since 2014, quick build wing and slow build fues., - dual Skyviews with complete system, two radio and not much else. Interior completely finished with Zolatone. CF plenum. 1624 lbs, FLYING after a 21.5 month build.
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