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#4653814 - 02/02/18 10:01 AM Opposed Piston Engine-3 cyl.
Speak2Mountain Offline


Registered: 04/07/17
Posts: 351
Loc: Mississippi

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#4653855 - 02/02/18 11:11 AM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
Danno Offline


Registered: 10/07/12
Posts: 2023
Loc: Northern Ontario, Canada
Interesting but I see some pretty big challenges:
Emissions - Fixed port 2 strokes do not do well with this
Weight - extra crankshaft and supporting block structure is heavy
Weight distribution - the extra weight is all high, no good for CG, so hard to adapt to cars
Packaging - It is a tall heavy engine - again maybe target use is SUVs and Trucks.
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#4653893 - 02/02/18 12:04 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
CT8 Offline


Registered: 10/09/14
Posts: 11233
Loc: Idaho
Interesting but then I remember whenn the media was pushing how great the Wankle would be. Yes I am a skeptic. The fuel injected out board engines for example are more complicated that the old carb engines but their performance and emissions are stellar in comparison. Good mpgs are always a plus . Over the past year with the driving I do I have been geting 21 to a bit over 23 mpg on my 2015 F150 . More Mpgs would always be better with a lower cost of operation [long term reliability] Lets hope it is a plus and pans out to benefit us all.

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#4653909 - 02/02/18 12:34 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
Cujet Offline


Registered: 02/15/03
Posts: 7239
Loc: Jupiter, Florida
We can do a number of things to improve thermal efficiency. One is to increase the displacement of a cylinder by using fewer but larger cylinders. As this results in lower thermal loss to exposed surface area. This also serves to reduce piston ring swept area, reducing friction.

Low heat rejection engines can be built using coatings to reduce the transfer of combustion heat to surfaces. Or engines can be operated at very high temperatures, thereby reducing heat flow. (an opposed piston engine is the latter type) as the pistons operate at very high temperatures. It eliminates the cylinder head as a thermal path.

Also, like the modern and hyper efficient (41%) Prius engine, configure the engine to have a higher expansion ratio (more expansion than compression) . Done with intake valve timing AKA Atkinson cycle. In opposed piston designs some think it can be done by port and piston timing via geometry. Possibly including the use of different stroke lengths, different connecting rod lengths, differing piston positions, and so on.



This design may accomplish some of that inherently, however, I fail to see how the predicted huge gains are met. 45% thermal efficiency is, at the moment, an area of operation reserved for well refined diesel engines.


Edited by Cujet (02/02/18 12:36 PM)
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#4653916 - 02/02/18 12:39 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
DoubleWasp Offline


Registered: 05/21/12
Posts: 5293
Loc: Fort Lauderdale, FL
Eliminating the cylinder head and combustion chamber is eliminating a major area of thermal loss. Further, the heat that used to be lost instead goes to another piston.

Could be some real game changing stuff.
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#4653918 - 02/02/18 12:41 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
CT8 Offline


Registered: 10/09/14
Posts: 11233
Loc: Idaho
Could the gas exhaust vs the diesel exhaust be easier to clean up?
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#4653937 - 02/02/18 01:15 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
OneEyeJack Offline


Registered: 09/14/10
Posts: 7485
Loc: S California
I think the Freevalve engine is the next step.

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#4653948 - 02/02/18 01:25 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
Miller88 Offline


Registered: 04/09/08
Posts: 12755
Loc: Onondaga County
For some reason the video wont' load, but if it is what I think it is, look up the commer TS3 ...
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#4653956 - 02/02/18 01:31 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
ragtoplvr Offline


Registered: 01/14/15
Posts: 542
Loc: missouri
The most efficient engine at this point is the Wartsilla 31. Of course, with a bore of 11.8 inches, 16.7 inch stroke, nearly 1000 horsepower per cylinder, and max RPM under 1000, not practical for land transport. Really efficient though.

Rod

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#4653997 - 02/02/18 02:37 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
A_Harman Offline


Registered: 10/01/10
Posts: 6950
Loc: Michigan
Opposed piston engines go back for more than 100 years, and were making 40%+ thermal efficiency long ago.
The English had successful OP engines for ship propulsion by the early 1920's, and some of those included waste heat recovery.
The Germans had the Junkers 204 OP diesel for commercial aircraft before WW2, and the 207 version was even turbocharged.
The Americans had the Fairbanks Morse 38 D 8+1/8 for submarine propulsion in WW2, and diesel electric locomotives postwar. That engine is still being constructed in Beloit, Wisconsin.
Then there is the Napier Deltic that is a 3-bank, 18-cylinder OP that was used for locomotives and Royal Navy MTB's. Lovely engine, sounds like a Detroit Diesel on Benzedrine.
I think Achates may be onto something. Cummins recently bought into their project to make a 4MW engine for power generation.
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#4654023 - 02/02/18 03:38 PM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
PandaBear Offline


Registered: 08/05/02
Posts: 14269
Loc: Silicon Valley
The rings and pistons would be scraping all over the exhaust ports, how is it going to last at all?
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#4654090 - 02/02/18 05:00 PM Re: Opposed Piston Engine-3 cyl. [Re: Danno]
JamesBond Offline


Registered: 12/13/06
Posts: 863
Loc: midwest
Originally Posted By: Danno

Weight distribution - the extra weight is all high, no good for CG, so hard to adapt to cars
Packaging - It is a tall heavy engine - again maybe target use is SUVs and Trucks.


Turn it on its side? Subaru does it.(kinda)

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#4654125 - 02/02/18 05:29 PM Re: Opposed Piston Engine-3 cyl. [Re: Miller88]
Silk Online   content


Registered: 07/26/03
Posts: 4619
Loc: New Zealand
Originally Posted By: Miller88
For some reason the video wont' load, but if it is what I think it is, look up the commer TS3 ...


Yes, a rehash of the TS3, but using an extra crank instead of the rockers in the TS3. We didn't hear it running (I wonder why)... I reckon if you heard it running you'd be sold - the TS3 was the best sounding engine ever.
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#4654425 - 02/03/18 01:05 AM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
Linctex Offline


Registered: 12/31/16
Posts: 6186
Loc: Waco, TX
Originally Posted By: Silk
Yes, a rehash of the TS3, but using an extra crank instead of the rockers in the TS3. We didn't hear it running (I wonder why)... I reckon if you heard it running you'd be sold - the TS3 was the best sounding engine ever.


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#4654439 - 02/03/18 02:30 AM Re: Opposed Piston Engine-3 cyl. [Re: Speak2Mountain]
Shannow Online   content


Registered: 12/12/02
Posts: 40184
Loc: 'Stralia
Back in the late '80s, I was doing drawings on jamming a couple of 186s together and opposed pistons...all ideas, no practicality.

If you start messing with crank timing and rod length/stroke, you can achieve a lot of different effectss, including having the pistons "chasing each other with variable volumes at either end...fun with geometry and physics.

Here's the inventor.

I like him


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