Lightest diesel engine known to man

[Ulysees]

Which would that be?

I hear diesel engines are always heavier than equivalent gasoline ones. I saw some portable electricity generators the other day, and the truly portable ones were all gasoline-based.

What's the lightest diesel-based electricity generator you know?

 

[Mech_Engineer]

I hear diesel engines are always heavier than equivalent gasoline ones. I saw some portable electricity generators the other day, and the truly portable ones were all gasoline-based.

Saying that "equivalent" diesel engines are always heavier is somewhat misleading; how are you defining their equivalence? Displacement? Horesepower? Torque?

The reason diesels are usually heavier on a per-displacement basis is because they deal with much higher compression ratios (over 20:1 instead of 9:1) and so have to have much stronger internal components and blocks to deal with the higher pressures. However, a diesel will also have more torque than a similar displacement gasoline engine.

Small Diesel engines do exist. Take for example, this roto-tiller:

http://www.minelinks.com/tools/diesel-tiller.html

 

[NateTG]

Small Diesel engines do exist. Take for example, this roto-tiller:

http://www.minelinks.com/tools/diesel-tiller.html

I'm not sure what the original poster meant by 'light'. Despite weighing 1300 pounds, this could be considered a light diesel engine because it has high power density
http://en.wikipedia.org/wiki/Junkers_Jumo_205

1-2 cc compression ignition models are popular for modelers e.g.:
http://www.modelenginenews.org/mate/index.html

 

[Ulysees]

1-2 cc compression ignition models are popular for modelers e.g.:
http://www.modelenginenews.org/mate/index.html

This is amazing!

I was just looking for a diesel-fueled electricity generator that is as light as possible. The lightest diesel engine that exists for a rated output of 1-3 kW. Which would that be?

 

[brewnog]

You can get a little 2.5kWe Yanmar genset which weighs about 65kg. Whether this is the smallest/lightest known to man, I have no idea. Those model engines are pretty small, but I imagine someone's done a nano-scale one.

What is your application?

 

[NateTG]

I was just looking for a diesel-fueled electricity generator that is as light as possible. The lightest diesel engine that exists for a rated output of 1-3 kW. Which would that be?

No clue. That's 1.5-5 HP. I know that there are manufacturers that sell diesels in that size range. Regardless, I expect that it's usually going to be cheaper and easier to look into an off-the-shelf solution for your generator.

 

[Ulysees]

What is your application?

I want something that I can easily carry with me outdoors for powering tools, pumps, water purifiers, maybe a fridge. Actually I may need more than 3 kW later, but portability is essential at this stage.

 

[Ulysees]

How much power does a small aircraft need?

 

[brewnog]

I want something that I can easily carry with me outdoors for powering tools, pumps, water purifiers, maybe a fridge. Actually I may need more than 3 kW later, but portability is essential at this stage.

Well have a look at what power demand you need. Why you you want diesel rather than petrol?

How much power does a small aircraft need?

How big is a small aircraft? The smallest I made was quite happy being propelled by a rubber band.

 

[Ulysees]

A real aircraft I meant. We've seen a model aircraft's engine haven't we.

 

[Mech_Engineer]

There are definitely off the shelf protable diesel generators in your power output range. Saying you want the generator to be "the smallest known to man" is somewhat misleading as it insinuates price is not an issue and you need it to be super, super small. When you say you want it to be light, how light? It seems to me that generators in the 3kw range will weight about 100-150lbs, so that's pretty much what you will be looking at...

Here is a nice looking 4kw Diesel unit, weighing in at 120lbs:
http://www.peakpowertools.com/Portable-Generator-Diesel-Pramac-3700-Watt-4kW-p/gpr04601.htm

If weight is of supreme importance (as in you need to be able to dead lift it by yourself), it's likely you'll be stuck with a 1-2kw gasoline-powered unit that weighs less than 100lbs. If you don't mind rolling a generator around, then you can pretty easily move a 150 lb model. Because gas generators are so much more common, they are available in smaller peak outputs as well as much lower prices.

 

[Ulysees]

Why you you want diesel rather than petrol?

Because diesel engines require less maintenance, and are more reliable. Also I think I can make the fuel myself, if things ever get this bad. 99.9% ethanol is much harder to make from vegetables.

 

[Ulysees]

When you say you want it to be light, how light?

I didn't say light, I said the lightest known to man. Expected some alternative alloys being used, don't know what those model-aircraft ones are made of, probably not steel.

 

[brewnog]

So, your requirements so far:

- Lightest diesel engine known to man, installed in a generator
- 1-3kW electrical power
- Low maintenance
- High reliability
- Tolerance to 'home made' fuels
- Portable enough to be carried alone?

If you find some way of prioritising those, let us know; because many of them are direct trade-offs.

 

[brewnog]

By the way, the traditional benefits of Diesel engines of reliability and low maintenance (as compared SI engines of equivalent output) don't really hold true on a very small scale.

A lot of reliability tends to be "designed in", rather than being an inherent feature of the fuel type itself; and then it's usually on industrial, medium/heavy duty engines where weight is not a primary consideration. Low maintenance is primarily a result of mechanical simplicity (as well as oil life), but these advantages tend only to be seen when running larger engines for long periods of time (thousands of hours); and very small SI engines are simple affairs anyway.

 

[Ulysees]

By the way, the traditional benefits of Diesel engines of reliability and low maintenance (as compared SI engines of equivalent output) don't really hold true on a very small scale.

A lot of reliability tends to be "designed in", rather than being an inherent feature of the fuel type itself; and then it's usually on industrial, medium/heavy duty engines where weight is not a primary consideration. Low maintenance is primarily a result of mechanical simplicity (as well as oil life), but these advantages tend only to be seen when running larger engines for long periods of time (thousands of hours); and very small SI engines are simple affairs anyway.

That's cool, thanks. Regarding priorities, let's start with the lowest weight currently available at this power rating, subject to the contraint of diesel as a fuel. I'm sure that's from an aircraft engine.

 

[Mech_Engineer]

That's cool, thanks. Regarding priorities, let's start with the lowest weight currently available at this power rating, subject to the contraint of diesel as a fuel. I'm sure that's from an aircraft engine.

There are no diesel aircraft engines available in the power rating you've specified. The specification is too big for R/C applications, but too small for ultralight aircraft applications. Most ultralight planes use 50-100hp engines that run on aircraft-grade fuels, not diesel.

I think you're basically looking for the lighest commercially-available diesel generator in the 1-3kw range. Such generators will probably weigh in at a minimum of 80 pounds. You're not going to find any diesel generators that use all-alloy blocks because cost is far more important than weight for a generator.

 

[brewnog]

I think you're basically looking for the lighest commercially-available diesel generator in the 1-3kw range. Such generators will probably weigh in at a minimum of 80 pounds. You're not going to find any diesel generators that use all-alloy blocks because cost is far more important than weight for a generator.

Good advice.

http://chinaxingyue.manufacturer.gl...gine/1001030490/Air-Cooled-Diesel-Engine.htm#

That's pretty lightweight, but you'd have to build it into a generator yourself.

 

[Ulysees]

Such generators will probably weigh in at a minimum of 80 pounds

Look at the rototiller you mentioned, it weighs just 70 lb with all the equipment.

 

[Ulysees]

Good advice.

http://chinaxingyue.manufacturer.gl...gine/1001030490/Air-Cooled-Diesel-Engine.htm#

That's pretty lightweight, but you'd have to build it into a generator yourself.

It says "OHV gasoline and diesel engine". It takes gasoline too or what? That can't be right. Maybe two of them are available.

 

[freerangequark]

Not sure if you meant Diesel as in Diesel fuel, or in principle. Small model airplane engines have a glow plug and ignite from the heat generated during compression. I have seen them as small as .020" Cubinc Displacement, but they don't burn Diesel Fuel.

-FRQ

 

[Ulysees]

What other fuel ignites by compression and can be home-made?

 

[freerangequark]

The 2-stroke model airplane engine is an internal combustion engine usually burning 'glow' or 'nitro' fuel consisting mostly of alcohol with nitromethane to help combustion and castor oil for lubrication of the metal parts

The two stroke principle means that there is fuel ignition on every second stroke of the piston in the cylinder. When the piston is on its down stroke down the cylinder, fuel and air will enter the combustion chamber between the top of the piston and the cylinder head. When the piston reaches the bottom of its stroke and starts to rise again it then compresses the fuel/air mixture in the rapidly shrinking volume of the combustion chamber. The fuel/air mixture is ignited by the glow plug just as the piston reaches the end of it's upstroke. The glow plus is so called because it contains a platinum wire that continues to glow from a catalytic process and the heat of the last fuel ignition. The new explosion forces the piston back into the next down stroke.

-FRQ

 

[Ulysees]

alcohol with nitromethane

Definitely not home-made then.

Anything with actual diesel fuel? Maybe using several model-helicopter engines might add up to the required power. But does any of them take diesel or oil as a fuel?

 

[freerangequark]

Definitely not home-made then.

Anything with actual diesel fuel? Maybe using several model-helicopter engines might add up to the required power. But does any of them take diesel or oil as a fuel?

Gas Model Helicopter engines are the same as airplane engines, except for maybe a larger head/heatsink. There are also 4 stroke glo-engines and their fuel is slightly different.

I don't know of any that run on Diesel fuel.

-FRQ

 

[Mech_Engineer]

"Real" diesel cycle R/C aircraft engines do exist in that they use compression-ignition; however, it seems that they don't run on diesel fuel, but rather a high ether content kerosene. Looking around briefly, I was unable to find an R/C engine that actually runs on diesel fuel.

Diesel engines are another choice but are the least common out of all the IC engines.

Diesel model airplane engines, such as the PAW shown right, are typically used in vintage rc airplanes to keep the model as traditional as possible.
Such engines were being manufactured before glow plug technology, and so were the first IC engines to be used in radio control flying.

Diesel engines do not use any form of plug for ignition, but instead rely on the fuel/air mixture inside the combustion chamber to ignite from the friction heat generated by the piston moving up and down as the prop is flicked over to start.
The pressure inside the chamber can be increased or decreased by turning a threaded screw on top of the cylinder head; increasing pressure aids ignition of the fuel/air mixture. The fuel is a special mix that has a high ether content, which is easily ignited.

 

[Ulysees]

Those helicopter engines have got to be more powerful for the same weight of aircraft, that's why it must be the place to look for a big model engine. Looking for the lightest available engine for a 1-3 kW generator. The engine NateTG mentioned seems to run on actual diesel fuel:

"It was produced for more than 10 years and sold here in Oz and in the USA (where it even comes with a nice little can of diesel fuel!)"

http://www.modelenginenews.org/mate/index.html

So who makes a bigger one of those?

 

[Mech_Engineer]

Those helicopter engines have got to be more powerful for the same weight of aircraft, that's why it must be the place to look. Looking for the lightest available engine for a 1-3 kW generator.

Of course helicopters have to have powerful and lightweight engines, that's why they use 2-stroke nitromethane. 2-stoke nitro engines are pretty much the highest power/weight ratio you can get in any kind of engine in any size. There are many 3-4hp models that can be used in R/C planes, cars, and trucks. Their maximum speed is usually in the 30-40,000 rpm range...

The engine NateTG mentioned seems to run on actual diesel fuel:

"It was produced for more than 10 years and sold here in Oz and in the USA (where it even comes with a nice little can of diesel fuel!)"

http://www.modelenginenews.org/mate/index.html

So who makes a bigger one of those?

The page does say it runs on Diesel fuel, but I'm not sure I believe it. If it did run on diesel alone, without any additives, it would be a very rare engine indeed. Also, that particular engine was a custom engine people built in their at-home foundries according to the article...

I found some threads in R/C forums with people asking about tiny engines that run on straight diesel fuel; the consensus is was universal- they don't exist.

I'm kind of thinking if you want a tiny engine that can burn various forms of home-made fuels, you'll need a turbine.

 

[Mech_Engineer]

The smallest diesel engine I've been able to frind thus far is the Yanmar L48V. It is a single cylinder, 219cc 4.2hp engine. The pull-start model weighs 58.4 lbs.

http://www.yanmar.com/store/item.asp?ITEM_ID=52&DEPARTMENT_ID=62

 

[Mech_Engineer]

Of course helicopters have to have powerful and lightweight engines, that's why they use 2-stroke nitromethane. 2-stoke nitro engines are pretty much the highest power/weight ratio you can get in any kind of engine in any size. There are many 3-4hp models that can be used in R/C planes, cars, and trucks. Their maximum speed is usually in the 30-40,000 rpm range...

I should go ahead and qualify this statement-

2-stroke nitro motors have the one of highest specific power outputs for recipricating piston-cylinder engines, both in terms of displacement and consequently weight. Turbines however are capable of achieving far higher specific outputs than any piston engine can.

Perhaps if you're insterested in super-lightweight power generation and cost is not a problem, you could adapt a hobby-grade turbine onto a geerator unit. There are hobby-sized turbines that put out 5hp or maybe higher, and can weigh 5 or 6 pounds. Paired with the fact that turbines are less restricitive as to what they can be run on, it might be possible to adapt a turbine to run on less coventional fuels.