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New Diesel design #4533809
10/04/17 12:45 PM
10/04/17 12:45 PM
Joined: Apr 2017
Posts: 429
Utah, USA
28oz Offline OP
28oz  Offline OP
Joined: Apr 2017
Posts: 429
Utah, USA


-----------------
1990 Nissan 300zx - Castrol Edge Euro 0W-40
2004 Nissan Quest - Pennzoil Platinum Euro 0W-40
2003 Ford Excursion 7.3 PSD - Mobil 1 TDT 5w-40
Re: New Diesel design [Re: 28oz] #4533830
10/04/17 01:05 PM
10/04/17 01:05 PM
Joined: Jul 2017
Posts: 1,292
Douglas County, Colorado
bigj_16 Offline
bigj_16  Offline
Joined: Jul 2017
Posts: 1,292
Douglas County, Colorado
Fairbanks-Morse, Colt-Pielstick and the like have had opposed piston two-strokes around for a while. Seems like the Army could adapt an existing engine, rather than have a new design

Re: New Diesel design [Re: 28oz] #4533983
10/04/17 03:46 PM
10/04/17 03:46 PM
Joined: Oct 2010
Posts: 7,002
Michigan
A_Harman Offline
A_Harman  Offline
Joined: Oct 2010
Posts: 7,002
Michigan
Interesting that Cummins is in a joint venture with Achates to develop a 21st century version of the opposed-piston diesel. There is also the OPOC engine being developed by Ecomotors that is an opposed-piston, opposed-cylinder configuration.

Hopefully the relatively poor combustion characteristics of the OP engine can be improved by new common-rail injection systems. Since it's being developed for the military, the engine is probably exempt from EPA emissions standards. (When I worked on a military engine for Cummins back in the 1990's, it didn't have to meet emissions standards.) The army would only be worried about no observable smoke.

The British had many OP diesels in military service back in the 1960's, made by Leyland and Rolls-Royce, and all based loosely on the German Jumo 205.

And there was the Rootes TS3 Commer that was used in commercial trucks for decades.

And the Napier Deltic in locomotives and torpedo boats.

Last edited by A_Harman; 10/04/17 03:47 PM.

1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck
Re: New Diesel design [Re: 28oz] #4534083
10/04/17 06:08 PM
10/04/17 06:08 PM
Joined: Jun 2003
Posts: 10,430
Illinois
javacontour Offline
javacontour  Offline
Joined: Jun 2003
Posts: 10,430
Illinois
Seems like there would be more reciprocating mass in an opposed piston engine.

I realize there is no valvetrain. However, it seems like the mass of the valve train is more than made up for in the mass of a second set of pistons and all the assorted hardware that makes that happen.

At least a valve train moves at half the crank speed. Opposed pistons move at the same rate.

What is the advantage of this setup vs more common engines we have today?


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Re: New Diesel design [Re: 28oz] #4534119
10/04/17 07:14 PM
10/04/17 07:14 PM
Joined: Dec 2002
Posts: 40,908
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 40,908
'Stralia
revolutionary ???

Only in an advertising puff piece.

Re: New Diesel design [Re: 28oz] #4534120
10/04/17 07:17 PM
10/04/17 07:17 PM
Joined: Oct 2010
Posts: 7,002
Michigan
A_Harman Offline
A_Harman  Offline
Joined: Oct 2010
Posts: 7,002
Michigan
Opposed piston engines are 2-strokes, so they have higher power density than 4-strokes. Historically, OP diesels were very fuel-efficient, achieving thermal efficiencies of 40% back in the 1940's. Combined crankshaft strokes are very long, giving a lot of expansion to the combustion gases. The biggest problem to the OP is that since it doesn't have a cylinder head, fuel must be injected from the cylinder walls, which leads to problems with spray impingement on the piston rims and cylinder walls, and poor distribution of fuel in the cylinder if only one injector is used. Two or more injectors could be used, but that adds cost.


1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck
Re: New Diesel design [Re: A_Harman] #4534195
10/04/17 09:45 PM
10/04/17 09:45 PM
Joined: Jun 2003
Posts: 10,430
Illinois
javacontour Offline
javacontour  Offline
Joined: Jun 2003
Posts: 10,430
Illinois
Originally Posted By: A_Harman
Opposed piston engines are 2-strokes, so they have higher power density than 4-strokes. Historically, OP diesels were very fuel-efficient, achieving thermal efficiencies of 40% back in the 1940's. Combined crankshaft strokes are very long, giving a lot of expansion to the combustion gases. The biggest problem to the OP is that since it doesn't have a cylinder head, fuel must be injected from the cylinder walls, which leads to problems with spray impingement on the piston rims and cylinder walls, and poor distribution of fuel in the cylinder if only one injector is used. Two or more injectors could be used, but that adds cost.


But is this an advantage over a two stroke with a conventional head?

Can't I just build a single piston in cylinder two stroke and not need to carry all the extra reciprocating mass of a second crank (worst case) and rods, pistons, etc? I could use a turbo to blow the cylinder full of air and displace any exhaust that doesn't escape on its own via its own heat and expansion.

Seems like unnecessary and wasteful complication compared to using what would be wasted exhaust energy to provide forced induction.


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Re: New Diesel design [Re: javacontour] #4534280
10/05/17 04:41 AM
10/05/17 04:41 AM
Joined: Dec 2002
Posts: 40,908
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 40,908
'Stralia
No cylinder head to lose heat to having the gasses "push" on it to oppose the piston...therefore less heat loss, and cooling system load/size.
No head gaskets.
No poppet valves (or sleeves/rotary seeing as this is touted as revolutionary), no cams etc.
Still needs a blower of some style if it's a two stroke, and there's no scavenging without forced induction at cranking speed.
Look at a DOHC set-up for a diesel with near vertical valves, and see how much "stuff" is otherwise above the head gasket.



Could nearly double the capacity with opposed piston for no more floorplan, and not much extra height.

Re: New Diesel design [Re: 28oz] #4534427
10/05/17 09:09 AM
10/05/17 09:09 AM
Joined: May 2015
Posts: 235
Indonesia
nyumski Offline
nyumski  Offline
Joined: May 2015
Posts: 235
Indonesia
for instance i saw enlightment and breakthrough instead of electric thing engine but i am worried it cant replace inline 6 cyl diesel engine LOL


14 Toyota 2.5 D4D - PTT 10w30 CL4 --> oil from Thailand
Re: New Diesel design [Re: 28oz] #4534531
10/05/17 11:23 AM
10/05/17 11:23 AM
Joined: Feb 2014
Posts: 593
Margate England
Claud Offline
Claud  Offline
Joined: Feb 2014
Posts: 593
Margate England
I wonder how much mechanical loss there is from the synchronising gears to the transmission input?.
It isn't a new concept, more a re-think of an old idea. Perhaps technology has advanced enough to deal with any inherent shortcomings.

Claud.

Re: New Diesel design [Re: 28oz] #4534532
10/05/17 11:23 AM
10/05/17 11:23 AM
Joined: Feb 2014
Posts: 593
Margate England
Claud Offline
Claud  Offline
Joined: Feb 2014
Posts: 593
Margate England
I wonder how much mechanical loss there is from the synchronising gears to the transmission input?.
It isn't a new concept, more a re-think of an old idea. Perhaps technology has advanced enough to deal with any inherent shortcomings.

Claud.

Re: New Diesel design [Re: Shannow] #4541263
10/12/17 02:36 PM
10/12/17 02:36 PM
Joined: Jun 2003
Posts: 10,430
Illinois
javacontour Offline
javacontour  Offline
Joined: Jun 2003
Posts: 10,430
Illinois
Originally Posted By: Shannow
No cylinder head to lose heat to having the gasses "push" on it to oppose the piston...therefore less heat loss, and cooling system load/size.
No head gaskets.
No poppet valves (or sleeves/rotary seeing as this is touted as revolutionary), no cams etc.
Still needs a blower of some style if it's a two stroke, and there's no scavenging without forced induction at cranking speed.
Look at a DOHC set-up for a diesel with near vertical valves, and see how much "stuff" is otherwise above the head gasket.


Could nearly double the capacity with opposed piston for no more floorplan, and not much extra height.


But can't you do much of that without opposing pistons? If you are using forced induction and this engine is already using ports, can't you have the best of both worlds by not using the opposing piston? Blow enough air in there, inject the fuel at the right time using an injector built into what would normally be the head, but is just part of the closed, cast engine block.

Perhaps I'm not considering the shorter stroke of each individual piston. I.E if two pistons are moving the same distance instead of one moving 2x the individual distance....

What, if anything am I missing here?


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