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Two stroke diesels???!!!
by
jtanguay
on 25 Jun, 2009 20:20
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#1
by
Turbinepowered
on 25 Jun, 2009 20:43
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They'll never pass emissions, not and retain any sort of power and efficiency.
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#2
by
Syncroincity
on 25 Jun, 2009 20:53
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Very cool concept!
Fairly low profile, maybe a little wider than a Subaru motor. Probably could be either water or air-cooled.
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#3
by
rabbitman
on 25 Jun, 2009 21:51
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There's already 2-stroke diesel aircraft engines, they're pretty new but very rare due to the high cost of converting over to it. They're turbo/supercharged, V4's, individual IP's and I THINK, watercooled heads and air cooled cylinders.
This double opposed piston thing has been around for a while, I never did understand 'em
And I'm sure you all know about the 2-stroke detroit diesel's.
Man I just watched the movies about this engine, sounds neat. It has an electrically assisted turbo, probably instead of using a supercharger to get it started.
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#4
by
jtanguay
on 26 Jun, 2009 00:10
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the newer technology is allowing two stroke diesels to run nearly as clean as a regular diesel. things like oil squirting for critical components etc. of course this means more to fail, but i'm really liking that there's no camshaft. the less rotating equipment the better, and the fact that every 2 strokes you get power, just means that these diesels can have a big advantage now over 4 stroke gasoline engines. 2 stroke gasoline engines will never be able to meet stringent emissions requirements.
i can see about 400 hp easily from a 4 stroke diesel.
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#5
by
aidan
on 26 Jun, 2009 00:33
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#6
by
jtanguay
on 26 Jun, 2009 01:03
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http://auto.howstuffworks.com/diesel-two-stroke1.htm
Thought about this a while ago when at college. Why couldn't it work on a TDI with a different sprocket on the cam and IP, and right ecu map? Serious over-simplifying I know
well there would be no cam on the two stroke
so it would only be the crank sprocket to the injection pump sprocket. but yes a TDI in this configuration would kick some serious butt!!!!!!!!!!!!!!
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#7
by
OM617
on 26 Jun, 2009 01:12
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2 strokes will not work in a modern car, they are too "dirty" and inefficient. They make about 1.8x the power of the same displacement 4-stoke, waste lots of usable air out the exhaust, require constant positive inlet air pressure (supercharger) to move air and they release raw oil into the exhaust.
That said, I love 2-stroke diesels. I'd jump at the chance to install a Detroit 453TA with Jake Brakes into a Mercedes and nothing sounds better than a race-tuned quad turbo 12V92.
http://www.youtube.com/watch?v=vJ8o1gxrW1I
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#8
by
aidan
on 26 Jun, 2009 01:13
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It doesn't have to be the same design as a petrol 2 stroke, have a look at that link in my last post. Instead of having the air intake in the side of the block, surely no reason the existing intake couldn't be used, and just have the cam spin twice as fast
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#9
by
OM617
on 26 Jun, 2009 01:24
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2 strokes by nature require positive air pressure to operate.
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#10
by
aidan
on 26 Jun, 2009 01:51
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Sorry didn't think right on that. Obviously the existing cam couldn't be used, but if pressurised air helps force the exhaust gas out, how about opening intake and exhaust valves near the same time.
piston at bottom of stroke>exhaust valve opens>intake valve opens>exhaust closes>intake closes>injection
Would this be possible with the right timing and a supercharger, or even a turbo?
Are there higher pumping losses normally on a 2 stroke, or is the pressurised air still metered by load?
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#11
by
airhead
on 26 Jun, 2009 03:37
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I dont understand why diesel 2-strokes would be any dirtier than a normal diesel. Its not like a petrol 2 stroke which is constantly blowing out unburnt petrol into the air. In diesel 2 strokes, the fuel gets burnt and gets blown out the exhaust valves by the incoming pressurised air. Sure, a bit of clean air will go out too but thats not such a big deal.
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#12
by
Turbinepowered
on 26 Jun, 2009 06:14
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I dont understand why diesel 2-strokes would be any dirtier than a normal diesel. Its not like a petrol 2 stroke which is constantly blowing out unburnt petrol into the air. In diesel 2 strokes, the fuel gets burnt and gets blown out the exhaust valves by the incoming pressurised air. Sure, a bit of clean air will go out too but thats not such a big deal.
It has to do with the amount of time for the combustion process. A two stroke has to do all four steps of internal combustion in two strokes, and to accomplish this they overlap a great deal. The exhaust port is uncovered well before the piston reaches BDC, and in most cases is very statically timed, so when the piston reaches it the exhaust "metastroke" has begun (Using terms from my old engineering professor's mouth). You have to accomplish exhaust, intake and compression all on that upswing, which results in a sometimes wildly varying amount of retained exhaust gasses, and your compression is going to vary with the speed of the engine. You get some of the worst airflow at the highest, power producing speeds, and the shorter effective power stroke means the need for either multiple nozzles to shove all the fuel in there at once, or one big-honkin nozzle that's going to smoke in the bottom end.
With cylinder wall ports you're going to leak some oil out of the exhaust, guaranteed. How much can be any amount greater than zero.
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#13
by
Turbinepowered
on 26 Jun, 2009 06:22
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Oh, and the OPOC has been in "development, almost ready to sell" for almost a decade now.
You may have lost the camshaft, but at the expense of doubling your piston mass and more than doubling your rod mass, which are oscillating masses and thus more power-robbing than simple rotating masses.
I get incredibly wary, snake-oil alarms going off when someone starts making claims like "4x the power and 40% fuel efficiency gains" all in one slam-home go. Yeah, it sounds cool, but so did the barrel engine.
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#14
by
jtanguay
on 26 Jun, 2009 08:02
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!!!!!