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centrifugal oil seperator pre turbo?
by
LeeG
on 18 Nov, 2006 20:43
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Thinking about ways to reduce the blowbye emissions of my car (and maybe reduce the amount of oil that will collect in the yet to be installed GTD IC) and I thought about using a centrifugal air dryer, where the air enters a cylinder tangentally so it spins along the surface of the cylinder before exiting. The centrifugal force extracts the moisture (oil) from the air and it drains to bottom. That seems like it would be more effective than using a wad of steel wool in the hopes that the oil will condense out.
Is anyone aware of one of these small enough? I have only seen massive ones on big air compressors.
Googling around I found this interesting passage in the description of a mercedes 8 cyl CDI diesel:
http://wwwsg.daimlerchrysler.com/SD7DEV/GMS/TEMPLATES/GMS_PRESS_KIT/0,2970,0-1-67958-1-1-text-0-67956,00.htmlAt the front end of the balancer shaft is an oil separator, which uses centrifugal force to act as a vent for the engine. The chain-driven device sucks gas containing oil out of the crankcase, before using gravity to filter out the oil. While the oil flows back into the engine, the gases move forwards out of the centrifuge and through a heated vent line into the intake pipe of the V8 engine. A valve takes care of the necessary pressure compensation.
That sound pretty cool, but also discouraging for my idea, if Mercedes had to use a power centrifuge, then a static device probably wouldnt be effective. Although I guess it is possible Mercedes did it this way to make it self draining.
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#1
by
Dr. Diesel
on 18 Nov, 2006 21:42
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many helicopters use centrifugal air filters for their engines. You'd have to size it properly to get the correct velocity. I wouldn't worry too much about any air restriction. One of our ground power units' (big perkins diesel) air filter was SO clogged that the corrugated rubber hose between it and the turbo imploded absolutely flat while running. The engine was still able to do the job, though it gave a good puff of smoke when you put a sudden load on it!
I made a steel wool separator for a particularly nasty 1.5L n/a engine. Godawful engine, made so much oil mist! Good thing was, it actually was safer to merge onto the highway under full oil runaway than on diesel. The acceleration was noticeably better. You could do it with the key off. :lol: Anyway, the wool can made that problem go away.
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#2
by
Chestrockwell
on 19 Nov, 2006 00:05
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Road draft? that's what I run, just a piece of hose from the valve cover hanging down below the block. Doesn't waste any oil... none.
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#3
by
QuickTD
on 19 Nov, 2006 01:05
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One of our ground power units' (big perkins diesel) air filter was SO clogged that the corrugated rubber hose between it and the turbo imploded absolutely flat while running. The engine was still able to do the job, though it gave a good puff of smoke when you put a sudden load on it!
Typical of the well maintained ground equipment I see... They typically call the electrical guy, nevermind the engine is smoking like a tire fire. The complaint is "low voltage, low frequency". No ***... Should read "engine pleading for mercy, electrics fine" The most common fix is really quite simple and is often undertaken by the ramp champs, er "personel" themselves, throw away the air cleaner. This also makes it easier to apply the ether when it gets cold and the thermostart is burned out... :roll: End of rant...
Back on topic, my lincoln diesel had just such an oil seperator mounted to the valve cover. It was about a 2" dia x 6" long plastic tube with another tube, 1" or so, coaxial to it and extending to within 1/2" of the bottom. The inner tube was connected to the intake. The crankcase gas entered the outer tube tangentally and exited through the inner tube after spiralling to near the bottom of the outer tube. A 5/16" drain line was connected from the base of this setup to the oil pan. I can't really say that it worked fantastic, there was always some oil in the turbo and intake, no better or worse really than the VW setup. perhaps in addition to the VW setup the results would be better. If you want pics I can get some.
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#4
by
LeeG
on 19 Nov, 2006 01:23
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QuickTD,
A picture of that Lincoln part would be nice, sounds like what I was considering making. Was there a check valve in the drain line to oil pan?
Chestrockwell,
I contemplated that, but driving to work one day with the CCV hose pulled out convinced me otherwise.....It looked like an engine fire every time I stopped with the smoke rising around hood :roll:
Off topic air cleaner story: Once had a RX7 that wouldnt start after a winter layup, then noticed the air cleaner box top was convex when cranking, flat otherwise. Squirrels had made a nice comfy home in the bottom of air box, full of shreadded filter and pinecone bits. Thankfully the filter was backed by a fine screen that held all the crud back.
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#5
by
QuickTD
on 19 Nov, 2006 01:33
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A picture of that Lincoln part would be nice, sounds like what I was considering making. Was there a check valve in the drain line to oil pan?
No check valve, but the hose emptied out above the oil level in the pan and the hose was small and long enough that it probably wouldn't provide much of an alternate route for the crankcase gases. I'll see about pics tomorrow.
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#6
by
QuickTD
on 19 Nov, 2006 21:47
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Here's the pic,
The oil seperator bolts to the side of the valve cover and hangs down (toward the drain) at about a 30º angle. The gases enter the port facing you in the picture and exit out the large spigot on the right. The small spigot on the left is where the drain hose connected to the oil pan. The center tube doesn't go down as far as I thought, only 3/4" or so past the side port. It doesn't come apart without a big hammer, so I can't really show you much more...
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#7
by
LeeG
on 20 Nov, 2006 01:40
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thanks. Is the cylinder tapered a bit? Too bad it has an application specific inlet, it would be easier to try if it just took a hose. So maybe I will have to make one.
I just realised our new dishwasher uses a power centrifuge to take the moisture out of the air during the drying cycle, rather than just exhaust it like most do.
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#8
by
QuickTD
on 20 Nov, 2006 10:20
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Thats not an illusion, it is tapered a bit. You could probably just jam a hose over the inlet for a test. Finding one of these things might be tricky though, the engine it came from is a BMW 2.4TD, used in the lincoln, 524 and some "vixen" motorhomes.
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#9
by
Dr. Diesel
on 21 Nov, 2006 02:35
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interesting item!
Funny, the word 'Vixen' doesn't quite conjur up images of motorhomes for me... :? :lol: