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Has anyone dieselized a 26cc thru 50cc gas engine yet?

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Has anyone dieselized a 26cc thru 50cc gas engine yet?

Old 11-10-2009, 08:04 AM
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Hobbsy
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

Dar, I have done my share of experimenting, I bought some Gadget fuel and mixed it one quart of Gadget to one quart of SoyBean oil that was intended to be used in Diesel pickups as an additive, Willie Nelson stuff. It made a lot of water like glow fuel does and left a reddish orange deposit in the center of the piston. Then I mixed the Gadget with the new clean, green Diesel fuel from truck pumps, it worked much better and smelled better than kero. It shows promise but I don't posses the equipment to do this sruff accurately enough to come with some facts.
Old 11-10-2009, 08:18 AM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

Dar, I don't get it. Why is one person exempt from your negativity and another is not? While earlwb is a fairly recent member here, it sure looks like he does a fair bit of research and experimenting himself. The question was not about the merits of such a conversion in the first place.

If diesel is so wasteful, RCU might as well do away with the glow and diesel forums and leave only the "supreme" gasoline forum.
Old 11-10-2009, 06:00 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

If we weren't wasting money on playing with radio control model airplanes then we would be saving our money or spending it a lot more wisely than on frivilous toys like radio control hobbies.

This is a hobby, people all like to try different things and get enjoyment out of doing something different or experiment with something to see what happens.  Some people play with RC cars, or RC boats, or RC airplanes. or turbo jets, rockets, pulse jets, free-flight, gliders, sailboats, scale boats, control line and so on.
I am sure someone who spent three years building a very exact scale highly detailed scale model boat doesn't consider it frivilous.
But others might.

Some people thought I was wasting a lot of time, et cetera when i was building my own steam engines. such obsolete technology nowadays. But I still considered it great fun.

Old 11-10-2009, 08:15 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

I once saw the 60CC Super Tigre twin with diesel heads on Ebay. It went so cheap I was sorry I didn't bid. I couldn't figure out what I would do with an engine that large though. It would be interesting to see, along the lines what Andy was thinking, what an ideal fuel mix for a large conversion might end up being. Most of the stuff I do these days is four stroke so I won't be investigating large two stroke model diesels anytime soon.
Old 11-10-2009, 10:05 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

I have a SuperTigre 4500 I'm going to convert, I have a MasterAirscrew 20x10 for it. I'm going to put about 32 oz more glow fuel through it then try it as a Diesel. It has very good compresion at flipping speed.
Old 11-10-2009, 11:03 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

Well one thing to think about that I forgot to mention was the dieselfuel isn't all that expensive. A diesel uses less fuel than a glowengine.
So a diesel uses about 1/4 to 1/3 of the fuel that a glow engine uses. some engines are a bit more frugal than that too.
So the gallon that Tower Hobbies sells at $30.00 would last 3 to 4times as long as glow fuel in the same engine. So you could say itwould cost about $7.50 to $9.00 run the diesel for the same amount of timethat a glow engine runs.
So technically the diesel winds up being more economical than a glowengine, even though pre-mix diesel fuel appears to be more expensive.
Gasoline is only somewhat cheaper than that then. As usually you would get a really good oil to mix with the gasoline and the really good oils cost more. Plus the gasoline consumption is still not as good as a diesel engine.
If one converted a engine, say a OS 3500 or a big Supertigre to spark ignition and ran it off of gasoline, and then converted it to diesel and ran it, the diesel conversion would still use less fuel for the same runtime.


If one wants to talk about frivolous wasting. What about the turbo fan jet hobbyists? The cheapest jet engine is around $2,500 US. But you still have to put it into a plane and all to be able to run it. The fuel consumption on a small jet engine even is pretty spectacular. But it is still fun to watch them put one of those jets through its paces.

I just had a thought. If someone dieselized a radial engine. The engine wouldn't need to rev up much, say under 4,000 RPM. I wonder if it would really sound like a radial engine flying around then. At present a radial engine only sounds realistic at idle and a little faster than that. As soon as you start flying around they don't sound any better than a single cylinder engine. The real radials were huge, developed copious amounts of horsepower at really low RPMs. I remember one radial developing like 2,500 hp at 1750 rpm. So to get the sound one would need to keep the rpms down low. A diesel just might do it.


Old 11-10-2009, 11:35 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?


ORIGINAL: gkamysz

Dar, I don't get it. Why is one person exempt from your negativity and another is not?
Greg,


I guess I just like David Hobbs better...


But no; there are things that require quite a large investment; which in turn produce a continuous waste...
Such is the installation of a Diesel head on a gas engine...

Experimenting is reasonable, however.
Old 11-10-2009, 11:43 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

Model diesels differ from full scale diesels quite a bit. A full size diesel with injection is a stratified charge type and is virtually always run "lean" when you compare total air in the cylinder and fuel consumed. A model diesel is carbureted and has a hopefully homogeneous mixture in the cylinder when it ignites. The trouble is that it's very difficult to get a model engine to run at stoich ratios, and it virtually always runs rich. There is a big improvement over glow, but the type of efficiencies seen in full size diesel simply can't be realized in model diesels. The torque that injected diesels make doesn't exit in model diesels either. Model diesels are capable of virtually the same RPM as their glow counterparts. While many diesel converted glow engines do show greater torque than on glow, this will be throughout the operating range. My 48 or 52 size four stroke diesel makes notably less torque at 4000RPM than it does at 8k-10kRPM. Modern full size turbo diesels make tremendous power due to turbocharging. Naturally aspirated diesels are virtually nowhere to be found today. An engine's power output is roughly proportional to it's mean piston speed. The smaller the engine gets, the faster it needs to turn to achieve a given piston speed and volume specific power output. So large engines turn slowly, while small engines turn quickly. Turbochargers basically don't scale well under 60HP. Unfortunately, you can't do much about that.
Old 11-11-2009, 03:30 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

Greg,


This is hardly the only issue that makes model Diesels less fuel-efficient than their full-size counterparts...

While methanol has an ideal (complete burn) stoichiometric ratio of ~6.5:1, but since the oil does not burn, o% nitro fuel has an overall stoichiometric ration of ~5.2:1, real Diesel is just like gasoline/petrol, at 14.7:1.
Basic model Diesel fuel, is comprised of 37.5% ether, 37.5% and 25% oil.
Kerosene has an ideal stoichiometric ratio of ~18:1, which is high. But for ether it is 9.8:1 and the oil is, for all practical purposes, inert.

So model Diesel has a collective stoichiometric ratio of ~10.4:1... Twice as good as that of methanol based fuel.
But model Diesel fuel costs over twice as much as glow fuel...

If compared with real Diesel fuel, this is still a low number.


And, of a higher importance is the fact that full-size two-stroke Diesels, typically have four exhaust valves in the head and turbocharging, or supercharging, that allow virtually complete scavenging, without any fuel waste... Unlike our 'sleeve-valve' two-stroke Diesels, that lose a lot of fuel through the exhaust, at most throttle settings.

Old 11-11-2009, 05:27 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

ORIGINAL: DarZeelon

Greg,

And, of a higher importance is the fact that full-size two-stroke Diesels, typically have four exhaust valves in the head and turbocharging, or supercharging, that allow virtually complete scavenging, without any fuel waste... Unlike our 'sleeve-valve' two-stroke Diesels, that lose a lot of fuel through the exhaust, at most throttle settings.

Dar..

You forgotten the opposed-piston engine..

[sm=thumbs_up.gif]
Larger total porting area.
Exhaust gas is pushed out into a straight flow along the cylinder bore, resulting in a more complete emptying and filling of the cylinder.
Porting timing may be asymmetrical which is desirable.
That is, the exhaust port opens first, and the power is turned off last.
Better thermal efficiency because a larger proportion of the combustion chamber surface consists of pistons and a smaller proportion of energy needs to cool off.
High torque.

[sm=thumbs_down.gif]
More expensive to produce
Long engine


Old 11-11-2009, 11:24 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?


ORIGINAL: Motorboy

You forgotten the opposed-piston engine..
Jens,


Is there a current two-stroke Diesel, which uses this configuration?

It is not only expensive to produce, but it is also very heavy, in relationship to its displacement.
It requires several extra moving parts, that are neither small, nor light...[&o]
Old 11-11-2009, 11:42 PM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

http://www.ecomotors.com/

The stoich ratio of kerosene is very close to that of gasoline and diesel fuel. Ether is 11.1:1 Direct injection engines waste no fuel out the exhaust, except what doesn't or can't burn.

The stoich ratio of model diesel fuel is much leaner than glow but what are the real operational air/fuel ratios? It doesn't really matter what the air-fuel ratio is. What matters, if we are discussing fuel efficiency, is brake specific fuel consumption.
Old 11-12-2009, 12:48 AM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

ORIGINAL: DarZeelon


ORIGINAL: Motorboy

You forgotten the opposed-piston engine..
Jens,


Is there a current two-stroke Diesel, which uses this configuration?


Yes, in diesel locomotive, ship and tanks . In old days used in airship and airplane and power station (in Denmark to example used opposed-piston engine in power station. Now a museum http://www.youtube.com/watch?v=unAsUugK9zw ).

It is not only expensive to produce, but it is also very heavy, in relationship to its displacement.
It requires several extra moving parts, that are neither small, nor light...
See this link: http://en.wikipedia.org/wiki/Junkers_Jumo_205


Old 11-12-2009, 09:12 AM
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Default RE: Has anyone dieselized a 26cc thru 50cc gas engine yet?

That 2 cycle double action diesel in Copenhagen is awesome. If I ever get a chance to go to Denmark, I'll defintely love to go see it in person.
Thanks for sharing.

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