two piston engine OT

hot_rod

I read a blurb about this engine in Popular Science this month. Two cylinder with two pistons per cylinder, two stroke. Why didn't I think of that? They are looking at a 48% efficiency compared to the Prius engine at 37%, one of the most efficient engines available currently.



I remember a AC dozer engine my dad had back in the 60's. The Detroit diesel was a two cylinder two stroke diesel. Two stroke.



EcoMotors located in Michigan.



hr

TomM

emissions

I see one problem:  2 stroke emissions.  that's a no-no nowadays. 

here's a video:

http://www.youtube.com/watch?v=UesbkO3NvoY&feature=related

Rich Davis_2

Not Always

Not all 2-cycle engines use a gas-oil mixture.  I believe it was a Detroit Diesel that was 2-cycle.   And Fairbanks-Morse made engines that were 2 pistons per cylinder, no head, they used 2 cranks driving the pistons toward each other which compressed the air between them to cause the inigtion.

Charlie from wmass

Detroit diesels

They were not able to get the Detroit diesels to burn clean enough even by diesel regs. I am curious how more moving parts can make a more efficient engine. Looks like this requires more reading. Thanks for sharing.

Jean-David Beyer

Deltic engines

Deltic engines, mainly used in railroad locomotives, were an extreme case of this. They had multiples of three cylinders and three crankshafts. In each cylinder were two opposed pistons. Hence the name Deltic.



Here are some short videos of some English ones; each locomotive had two engines with 18 cylinders, 36 pistons each. First one is an animation of one running.



http://www.youtube.com/watch?v=wBTF5Ps4Scs



http://www.youtube.com/watch?v=9vLV2rxFHyE&NR=1



http://www.youtube.com/watch?v=0mpbscrOfO0&feature=related

Charlie from wmass

That was cooollll!!!

the time to engineer something that complicated. Now that was something new.

hot_rod

I thought we

had seen the limits of reciprocating engines also. Taking a piston from 0- 250 mph and stopping it 2 inches later to change direction seems old technology. But this looks to be quite a big improvement on that concept.



But the simplicity of an electric motor for example, with one rotating part and two bearings makes the internal combustion process look caveman-ish.



hr

Jean-David Beyer

Taking a piston from 0- 250 mph and stopping it 2 inches later to change direction

I once saw the loading of the connecting rod of a reciprocating 4-cycle gasoline engine with different design constraints. With old low performance engines, the maximum load was compression during the power stroke. But with modern high performance engines (such as those used in some sports cars and race cars), the maximum load is stretching of the connecting rod at the top of the exhaust stroke. In these engines, both the exhaust valve and the intake valve are open at the same time so the momentum of the exhaust gas going out sucks the gas-air mixture of the intake. The exhaust and intake systems are tuned to promote this.

bob_46

about half

About half the locomotives you see are GE the rest are Electromotive. The GE's are

4 stroke diesels the EMD's are 2 stroke diesels. In a Formula -1 engine , a 2.4 liter

v8 at 18000 rpm each piston comes to a stop 600 times per second.

TonyS

emissions no longer a problem

emissions ,since the perfecting of the direct injection two stroke outboard motor, The new two strokes are cleaner ,quieter and much higher hp to weight than any four stroke available. Not to mention much easier to rip down and rebuild.