I bought AntiSplat's oil-air separator, installed it on my RV-9A, IO-320 Lyc., CS prop, 490 hours since first flight in July, 2009, and have 7 hours flight time on the new oil-air separator so far. I could not find any reports on it, so here goes...
WHY I BOUGHT IT: I had an oil-wet belly, even with the oil-air separator I originally installed. I did not put the breather vent pipe over an exhaust pipe as suggested because I was concerned that engine movement might cause the exhaust pipe to hit the breather tube, and maybe oil would drip on the hot exhaust pipe after landing, risking an engine fire on the ground. The AntiSplat idea of injecting residual oil directly into the exhaust would solve these concerns. It sounded good on paper, and they sold me on the idea.
INSTALLATION: I give AntiSplat a score of 7 out of 10. Read on...
Opening the box, I found a beautiful oil-air separator with a fitting at the top to receive the crank case vent, a flare fitting at the bottom for return oil to the engine, and a vapor exhaust line at the bottom that connects to a vacuum valve that installs in an exhaust pipe. Also included was a length of hose to connect the crankcase breather and vacuum valve, a small-diameter hose with flare fittings at both ends to return oil to the engine, a 90-degree fitting and an adaptor to connect it to the engine (at a place that I didn't know existed), a vacuum valve, an adaptor pipe (that welds into the exhaust pipe) that the vacuum valve connects to. My initial thoughts: It will be a very difficult and risky installation. Should I proceed or send it all back? Am I up to this? I have an oily wet belly but the airplane flies fine, so do I really need to risk this installation? Anxiety attacked, and I set it all aside while I pondered what to do.
When I bought it, AntiSplat did not yet offer a saddle to install the vacuum valve on the exhaust. Instead, the stainless steel (SS) adaptor tube was to be cut off at an angle and welded into a hole in the exhaust pipe. I don't weld. I did nothing while I thought about how I would need to critically place the adaptor so that the vacuum valve would not touch the engine mount or anything else, and the exhaust pipe would need to be drilled, spot welded in place to assure the correct position, the pipe removed to finish welding the heavy SS adaptor pipe to the thin exhaust pipe and the two supplied braces welded in place -- I didn't like the prospects of such an installation -- I just knew it would certainly break off with vibration.
Then AntiSplat, obviously reading my distressed state of mind, immeditely came up with a sturdy SS saddle that attaches to the exhaust pipe with two SS clamps, with the SS adaptor already cut and welded in place, and probably sold at cost for $20. The weld is perfect. The part is super strong. Yes, this will work fine, and doesn't even require removing the exhaust pipe. I could then proceed without much risk.
I drilled an under-sized 1/2 inch hole in the exhaust pipe with an angle drill then ground it larger until the adaptor pipe in the saddle fit snuggly in place. I enlarged the hole with small sanding drums and a Dremmel stone until the fit was snug. Working like that, I could critically adjust the rotation position so that the vacuum valve would clear obstacles and be in the exact final position that I wanted -- I could not have done it better. I installed the vacuum valve on the adaptor, then clamped the saddle to the exhaust pipe. AntiSplat gets a 10 for the saddle -- I would not have ever installed the vacuum valve without it. This method of installation is 10X stronger than any direct weld to the thin exhaust pipe could ever be.
I mounted the oil-air separator high on the firewall. Two 1/4 inch bolts secure it. I found that the hose between the crankcase breather and the oil-air separator had a routing problem. I did not have an adaptor to connect to the old Vans 90-degree rubber hose adaptor for the old oil-air separator that I had removed. Can't stop now. I temporarily (until next annual in October) installed the hose in a long loop around the oil filter (mounted on a 90-degree adaptor and a 1.25 inch extension) -- not pretty, but its just temporary. I suggested to Allan (at AntiSplat) that they include a Vans 90-degree hose and a hose coupler to make the installation clean. They lost a point with me because of this. Connecting the vapor outlet hose to the vacuum valve was simple. Then I hit a big problem attempting to install the 90-degree flare fitting that returns oil to the engine at a point next to the prop speed governor: the engine mount was in the way by about 1/4 inch. Solution: I ran a 1/8 NPT tap into the adaptor and got about 3 additional threads (very difficult), and ran the 90-degree fitting into a 1/8 NPT dye until it could not go further (easy), again getting about 3 additional threads. That was enough to clear the engine mount. I suggested to Allan that they do this up front. They lost 2 points with me over this. I connected the oil return line (flare fittings on both ends), and the installation was complete.
FLIGHT TESTING: AntiSplat gets a 10 out of 10 for performance.
I felt that their claims needed a good test. If I ever dared to fill my oil level over 6.0000 quarts, the excess would blow out within the first 15 minutes of flight, contributing to the mess on the belly, and then I would see another 1/2 quart lower after another 15 to 20 hours of flight. I had 5.9 quarts showing on the dipstick, so I added a full quart, expecting the new oil-air separator to hold it at 6.9 quarts. Silly me. I flew for 35 minutes and found the oil level was down to 6 1/3 quarts. What??? My guess is the excess oil slugged out so fast that the small return line could not handle the flow rate, it overflowed the oil-air separator and ended up in the exhaust. After 6.5 additional hours of flight, the oil level is still at 6 1/3 quarts, and the belly (which my sweet wife spent an hour wiping clean) is still completely free of oil. With the old oil-air separator, I would have lost that last 1/3 quart within an hour, so, quite obviously, the new oil-air separator is doing a great job recirculating that last 1/3 quart of oil.
AntiSplat claims a small gain of HP because the vacuum valve pulls a negative pressure on the crank case. I cannot say for certain if I am getting any additional HP (without additional fuel flow) -- too many variables -- on XC cruise, I might be getting 1 or 2 knots more than before, but no more than that. Perhaps the last 1/3 quart of oil sloushing around the engine is absorbing the additional HP. It could also be that I installed the valuum valve too close to the end of the exhaust pipe -- about 12 inches -- and I am not getting enough vacuum to realize the improvement in HP. I have a wide-band oxygen sensor bung in the exhaust pipe where I would like to have installed the vacuum valve, so I had to compromise the installation a little.
OVERALL IMPRESSION:
I am quite happy with the performance. I was looking for a dry belly, and I got that. If I get an extra knot of cruise speed, that is OK too. Now, if AntiSplat includes a 90-degree hose and coupler, and modifies the return oil adaptor and fitting so it can be installed without modification, I could give them a perfect 10 score for installation.
Jim Skala [email protected]
WHY I BOUGHT IT: I had an oil-wet belly, even with the oil-air separator I originally installed. I did not put the breather vent pipe over an exhaust pipe as suggested because I was concerned that engine movement might cause the exhaust pipe to hit the breather tube, and maybe oil would drip on the hot exhaust pipe after landing, risking an engine fire on the ground. The AntiSplat idea of injecting residual oil directly into the exhaust would solve these concerns. It sounded good on paper, and they sold me on the idea.
INSTALLATION: I give AntiSplat a score of 7 out of 10. Read on...
Opening the box, I found a beautiful oil-air separator with a fitting at the top to receive the crank case vent, a flare fitting at the bottom for return oil to the engine, and a vapor exhaust line at the bottom that connects to a vacuum valve that installs in an exhaust pipe. Also included was a length of hose to connect the crankcase breather and vacuum valve, a small-diameter hose with flare fittings at both ends to return oil to the engine, a 90-degree fitting and an adaptor to connect it to the engine (at a place that I didn't know existed), a vacuum valve, an adaptor pipe (that welds into the exhaust pipe) that the vacuum valve connects to. My initial thoughts: It will be a very difficult and risky installation. Should I proceed or send it all back? Am I up to this? I have an oily wet belly but the airplane flies fine, so do I really need to risk this installation? Anxiety attacked, and I set it all aside while I pondered what to do.
When I bought it, AntiSplat did not yet offer a saddle to install the vacuum valve on the exhaust. Instead, the stainless steel (SS) adaptor tube was to be cut off at an angle and welded into a hole in the exhaust pipe. I don't weld. I did nothing while I thought about how I would need to critically place the adaptor so that the vacuum valve would not touch the engine mount or anything else, and the exhaust pipe would need to be drilled, spot welded in place to assure the correct position, the pipe removed to finish welding the heavy SS adaptor pipe to the thin exhaust pipe and the two supplied braces welded in place -- I didn't like the prospects of such an installation -- I just knew it would certainly break off with vibration.
Then AntiSplat, obviously reading my distressed state of mind, immeditely came up with a sturdy SS saddle that attaches to the exhaust pipe with two SS clamps, with the SS adaptor already cut and welded in place, and probably sold at cost for $20. The weld is perfect. The part is super strong. Yes, this will work fine, and doesn't even require removing the exhaust pipe. I could then proceed without much risk.
I drilled an under-sized 1/2 inch hole in the exhaust pipe with an angle drill then ground it larger until the adaptor pipe in the saddle fit snuggly in place. I enlarged the hole with small sanding drums and a Dremmel stone until the fit was snug. Working like that, I could critically adjust the rotation position so that the vacuum valve would clear obstacles and be in the exact final position that I wanted -- I could not have done it better. I installed the vacuum valve on the adaptor, then clamped the saddle to the exhaust pipe. AntiSplat gets a 10 for the saddle -- I would not have ever installed the vacuum valve without it. This method of installation is 10X stronger than any direct weld to the thin exhaust pipe could ever be.
I mounted the oil-air separator high on the firewall. Two 1/4 inch bolts secure it. I found that the hose between the crankcase breather and the oil-air separator had a routing problem. I did not have an adaptor to connect to the old Vans 90-degree rubber hose adaptor for the old oil-air separator that I had removed. Can't stop now. I temporarily (until next annual in October) installed the hose in a long loop around the oil filter (mounted on a 90-degree adaptor and a 1.25 inch extension) -- not pretty, but its just temporary. I suggested to Allan (at AntiSplat) that they include a Vans 90-degree hose and a hose coupler to make the installation clean. They lost a point with me because of this. Connecting the vapor outlet hose to the vacuum valve was simple. Then I hit a big problem attempting to install the 90-degree flare fitting that returns oil to the engine at a point next to the prop speed governor: the engine mount was in the way by about 1/4 inch. Solution: I ran a 1/8 NPT tap into the adaptor and got about 3 additional threads (very difficult), and ran the 90-degree fitting into a 1/8 NPT dye until it could not go further (easy), again getting about 3 additional threads. That was enough to clear the engine mount. I suggested to Allan that they do this up front. They lost 2 points with me over this. I connected the oil return line (flare fittings on both ends), and the installation was complete.
FLIGHT TESTING: AntiSplat gets a 10 out of 10 for performance.
I felt that their claims needed a good test. If I ever dared to fill my oil level over 6.0000 quarts, the excess would blow out within the first 15 minutes of flight, contributing to the mess on the belly, and then I would see another 1/2 quart lower after another 15 to 20 hours of flight. I had 5.9 quarts showing on the dipstick, so I added a full quart, expecting the new oil-air separator to hold it at 6.9 quarts. Silly me. I flew for 35 minutes and found the oil level was down to 6 1/3 quarts. What??? My guess is the excess oil slugged out so fast that the small return line could not handle the flow rate, it overflowed the oil-air separator and ended up in the exhaust. After 6.5 additional hours of flight, the oil level is still at 6 1/3 quarts, and the belly (which my sweet wife spent an hour wiping clean) is still completely free of oil. With the old oil-air separator, I would have lost that last 1/3 quart within an hour, so, quite obviously, the new oil-air separator is doing a great job recirculating that last 1/3 quart of oil.
AntiSplat claims a small gain of HP because the vacuum valve pulls a negative pressure on the crank case. I cannot say for certain if I am getting any additional HP (without additional fuel flow) -- too many variables -- on XC cruise, I might be getting 1 or 2 knots more than before, but no more than that. Perhaps the last 1/3 quart of oil sloushing around the engine is absorbing the additional HP. It could also be that I installed the valuum valve too close to the end of the exhaust pipe -- about 12 inches -- and I am not getting enough vacuum to realize the improvement in HP. I have a wide-band oxygen sensor bung in the exhaust pipe where I would like to have installed the vacuum valve, so I had to compromise the installation a little.
OVERALL IMPRESSION:
I am quite happy with the performance. I was looking for a dry belly, and I got that. If I get an extra knot of cruise speed, that is OK too. Now, if AntiSplat includes a 90-degree hose and coupler, and modifies the return oil adaptor and fitting so it can be installed without modification, I could give them a perfect 10 score for installation.
Jim Skala [email protected]
