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Old 06-29-2013, 12:47 AM   #1 (permalink)
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Ways to increase diesel engine efficiency?

Hello gang,

I was reading an article yesterday about a company who has developed an interesting diesel motor based on the rotary designed engine. The engine is quite compact with far less parts than of our traditional diesel designs. It also stated in the article it achieves greater than 50% efficiency.

Mr diesel himself stated that the theoretical efficiency of the diesel engine was 75%. If this is correct than we have a long ways to go even 20% would have huge gains in mpg for the average vehicle.

So what are some ways to increase diesel engine efficiency that can be applied to our current diesels now?

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Old 06-29-2013, 02:03 AM   #2 (permalink)
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Old 06-29-2013, 02:29 AM   #3 (permalink)
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Ways to increase diesel efficency?
Usually an EGR delete helps FE on larger diesel engines.
Cold air intake as long as temps stay above 20'F to 40'F, depending on the engine.
Increase the stadic compression ratio.
Water injection.
Belt driven fan delete if you have a belt driven fan and don't tow much.
Installing a larger more modern turbocharger on older generation engines.
A grill block during the colder months will improve aerodynamics and bring up temps quicker.
Unrestricted free flowing, short as possible exhaust.
Then you still have your general vehicle mods like aero improvements and EOC.

Check out the wiki list of mods here:
Main Page - EcoModder
1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
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Old 06-29-2013, 03:04 AM   #4 (permalink)
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Originally Posted by tjts1 View Post
Yes my apologies

Link = LiquidPiston unveils its ultra efficient, small diesel engine — Tech News and Analysis

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Old 06-29-2013, 05:57 AM   #5 (permalink)
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Supercritical fuel injection

Link = Supercritical Fuel Injection | MIT Technology Review

Wow seems pretty high tech

In a nutshell they are preheating the diesel before injection. They heat the diesel to 450 degrees Celsius under high pressure. They say they achieve it by utilizing the engines exhaust.

To me I think this would be difficult to achieve sustained high temps consistently. Some kind of electrically controlled flash boiler or transducer may be needed for system reliability. One would also have to be careful of starving the diesel engine. To me this would be like the ultimate way of leaning out the engine. We all know when you lean it out to much on a diesel it just dies on you! However by utilizing water/meth injection in conjunction may provide the needed fuel boost for steady reliable operation under load. Just up the meth to water ratio to improve combustion and prevent water lock.

I have heard of quite a few people trying to do this with gas cars as its much easier to vaporize gas fuel. However most people have mixed results as its supposedly hard to control and obtain the right air/fuel mixtures under the various driving conditions. To me the system would need to be variable in its operation to be effective. It would have to be able to adjust to the varying engine loads to be effective.

The other side similar to this supercritical fuel injection is fuel evaporation. Again used in gas tech and would not be applicable to diesels as they do not evaporate near as easily as gas.

Here is a link to one such unit I came across some time ago that seems to work reliably = 1st AGS Gasoline (Manufacturer of the Fuel Vaporizer MPG System) Carburetor Vaporizer Fuel Adapter

I think the term supercritical is simply a fancy term for vaporizing the fuel and is something that has been experimented with for along time. I think this is on the lines of the holy grail to supreme fuel economy. Supreme fuel economy would be in my opinion getting over 240mpg. It is encouraging that somebody is trying it with diesel because to this point there has been little attention given in this area of potential gain for diesel technology.

This research sets the stage for catalytic fuel cracking and is the holy grail of supreme fuel economy If a person was able to achieve this in an diesel or gas auto of average size they would be able to easily achieve 200+ mpg figures However we probably would not see them around to long LOL!

So some interesting concepts to think about as it pertains to increasing diesel engine efficiency.

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Old 06-29-2013, 07:51 AM   #6 (permalink)
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Transonic Combustion has a system for preheated supercritical untra high pressure injection. I think they are on to something.

Not so sure about a Rotary Diesel engine. One of the most basic flaws in a Rotary engine (patented in 1925 by the way) is the surface area exposed to combustion heat, as well as sealing the combustion chamber during compression and expansion at various operating temperatures. The piston in cylinder configuration is very hard, if not impossible to beat in that respect.

Persoanlly I have felt, for a decade, that the ancient (WW1 era) Rotary aircraft engine has a place today as a compression ignition diesel, but that is another discussion altogether.


I know argonne labs is working on a 60% efficient engine, but I doubt if 75% will ever be reached in a reciprocating engine, which is why I like the Rotary, which is NOT a reciprocating engine. Many debates here many years ago, I just feel that with modern technology, elimination of reciprocation is possible. While a Wankel type Rotary eliminates reciprocation there arre still oscillations involved, but sealing and heat loss to combustion chamber walls are, in my opinion, the killer of the Wankel.


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Old 06-29-2013, 03:05 PM   #7 (permalink)
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Thanks old mechanic for the link. That is a pretty cool setup tscombustion has going there. They address each component that would be needed for effective control of the supercritical diesel fuel. I am going to have to keep my eye on those fellas.

The Wankel engine is pretty interesting to me but I have very little knowledge of it. I just thought it was cool to see how small it was in comparison to the reciprocating equivalent I think that its a cool concept and especially since you can reduce part counts drastically.
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Old 06-29-2013, 07:09 PM   #8 (permalink)
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Interesting reading about rotary engines... I always equated rotary with Wankel, but see now there are other types of rotaries too. What options are there for a more efficient diesel engine that's not reciprocating?
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Old 06-29-2013, 09:03 PM   #9 (permalink)
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Hey Nachtritter,

"What options are there for a more efficient diesel engine that's not reciprocating?"

So to answer your question there are many emerging diesel engine designs being currently tested and look very promising. Some are completely new designs and some are old designs with efficiency upgrades.

I will try my best to give a solid run down of the options.

#1. OPOC = Opposed Piston Opposed Cylinder this is a novel design and takes two old designs and merges them into one. The first OPOC engine in theory was the Bourke engine Current company that is working on this is Ecomotor = Technology | EcoMotors

Article Link = The OPOC Engine, 100 mpg? | Fuel-Efficient-Vehicles.org

#2. Revetec Engine = The REVETEC Engine design consists of two counter-rotating “Trilobate” (three lobed) cams geared together, so both cams contribute to forward motion. Revetec = Revetec Australia - Technology

Article Link = The Revetec X4v2 | Fuel-Efficient-Vehicles.org

#3. Reisser cycle engine = The reisser engine uses a pair of opposing torus-shaped pistons (they look like a section of a doughnut) that oscillate in a rotary motion. Reisser = About

Article Link = Niama Reisser - A New Car Company is Born - Diesel Power Magazine

Article about the Reisser NR-1 super mileage prototype car = NR1

#4. Free Piston = The Operation of the engine is based on 'free pistons' (unrestrained by con-rods or crank shaft) being driven back and forth inside cylinders by controlled internal combustion. Permanent magnets are attached to these pistons and move through stator coils, thus generating electric power. Pempek systems = Free Piston Power Home

Article link = 5 Alternative Engine Architectures - How to Replace the Internal Combustion Engine - Popular Mechanics

#5. Scuderi = The engine is a split cycle design where In a conventional Otto cycle engine, each cylinder performs four strokes per cycle: intake, compression, power, and exhaust. This means that two revolutions of the crankshaft are required for each power stroke. The Scuderi Engine divides these four strokes between two paired cylinders: one for intake/compression and another for power/exhaust. Compressed air is transferred from the compression cylinder to the power cylinder through a crossover passage. Fuel is then injected and fired to produce the power stroke. In a standard Otto cycle engine, the pistons fire every other revolution, however, the Scuderi engine fires every revolution. The Scuderi must have at least two cylinders. In the Scuderi cycle, the power cylinder fires just after the piston has begun its downward motion (after top dead center, or ATDC). This is in contrast to Otto cycle design convention, which calls for combustion just before top dead center (BTDC) in order to allow combustion pressure to build.[12] The Scuderi Group says a thermal efficiency shortcoming seen in previous split-cycle engine designs is eliminated in the Scuderi Engine through the process of firing after top dead center. Firing ATDC in a split-cycle arrangement is claimed to eliminate the losses resulting from recompressing the gas.

Scuderi = Technology | Scuderi Engine

Article Link = 5 Alternative Engine Architectures - How to Replace the Internal Combustion Engine - Popular Mechanics

#6. MYT Engine = The MYT is an internal combustion engine of new design that features multiple firings in one cycle, producing enormous torque in a small area.

Angellabsllc = Angel Labs :: Mighty Engine Theory

Article Link = Directory:Massive Yet Tiny (MYT) Engine - PESWiki

Ok this is not a comprehensive list but it gets the ball rolling into the what I like to call the new age of diesel fueled engines. The 21 century will be exciting as these technologies become mainstream and available. Feel free to add to the list as there are other exciting designs out there honestly my fingers are starting to hurt so add to this list at your leisure

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Old 06-29-2013, 09:25 PM   #10 (permalink)
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Convert it to run as a homogenous charge compression ignition engine. No more need for turbocharger and near zero nitric oxide and hydrocarbon production when done correctly.

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