LeeHop

Ever seen a 4-stroke diesel? Does anyone make one today? Have any of you ever heard one run?

Here's a picture of a German 4 Stroke VT 1 D 1.0 cc diesel. Supposedly rather rare.

Cheers - LeeHop

Jim Thomerson

Come on, tell us where you found that picture.. Do you have a bid in?

Seriously, I wonder what the "compression lever" ??? sticking out of the crankshaft housing is for. Do you think it moves the crank up or down to adjust compression?

[email protected]

Dick Griswald in Arizona has one. He purchased it in Europe last year at the European SAM Champs. He says it runs great. The compression lever raises and lowers the crankshaft to vary the compression, I talked to Dick about it at the Eloy SAM contest in January 2006. Dick says he will bring it to the 2006 Muncie SAM Champs in September. This I got to see. I think he said he got it in the Czech Republic. Jack

AMB

Quite a solution to vary the compression, only the Germans would

come up with this one, wonder how they designed the front to maintain the bearing seal since it had to slide up and down

Wonder if Randy at RJL has seen this one would make a nice reproduction, he already has the 21 and 49 VT 4 strks

Hobbsy

My Feedback: (102)

Very nice, now if only there was a 1 cubic inch one.

gkamysz

My Feedback: (19)

http://modellmotoren.homepage.t-onli...ngl-start2.htm

BIN price on e**y is only $800. Looks like a great idea. Doesn't seem too practical for a bearing supported crank, but it could certainly be done. The crank is on an eccenctric adjusted by the lever.

Greg

LeeHop

Thankyou, Greg - I went to the site and clicked on the VT 1 D and found a very nice picture of the engine. If you click on "Details" don't be put off by the German text - just look at the construction pictures - totally awesome!

Cheers - Lee

Evil Homer

That is an awesome site, just drooling over his other engines which he has built, incredible!

Sport_Pilot

Actially not a Desel. Any true Diesel engines out there? Would be nice to run an engine on #2 fuel oil, and some mineral oil.

gkamysz

My Feedback: (19)

"True diesel"? Components do make a high pressure injected model size diesel don't seem to exist. This is as close as we can get(for now) and we like it.

Motorboy

Yes, both are difference how fuel are entered into the engine, but will come under the category as dieselengine because both big true diesel engine and small model engine are using compression as ignition source.

gkamysz...
There was a old Eisfeld modelengine with real pump and pop-off injector. Search the 4 stroke diesel engine here in Everything diesel, there are the picture of Eisfeld engine

Jens Eirik

gkamysz

My Feedback: (19)

Yes, Jens, I saw your Eisfeld pictures. There isn't anything in current production or even home built with injection, though. I've modified an OS FS.40 like that thread.

AMB

Model or full size injected or fuel mixture thru a side port if the only source of ignition is compression by definition it is a diesel regardless of the fuel. Glow engines have some times been refered to as semi-diesels this is really incorrect since although the power
is removed from the plug after starting and no external source of ignition the element stays glowing from catalytic action of methanol
on the element if the plug burns out the engine ceases to run hence compression does not keep the engine running, There have been
instances of a glow engine if hot enough and high compression will fire without power to the glow plug at that point it is a diesel at least
for the moment it fires martin

gkamysz

My Feedback: (19)

I wonder what RPM would be possible with an injected diesel. Most auto engines top out at 4-5k. It seems that the limit is due to how much fuel you can inject in the proper timing window. I think the ether in the fuel allows the kind of RPM we operate at.

Greg

Motorboy

Greg...

Not accurate answer, it is limited how to keep injector to closed between injection period, in hi rpm are difficicult to close the nozzle needle fast at place after injection period are ended cause indolence (inertia?) in nozzle needle against dieselfuel + limited of ignition lagg. To hi rpm more difficult to keep less ignition lagg.. The dieselpump are adjusted to keep limited max rpm and prevent to damage the engine.

Jens Eirik

Sport_Pilot

Actually model Diesel engines are not Diesel's. To be a Diesel engine it must operate at a constant pressure during the power stroke. To do that you must inject fuel into the engine at a constant rate during the power stroke. I am intrested in model Diesel's as an intresting power plant even if not a true Diesel. But the cost of fue puts me off. If they ran cheap fuel oil I would buy one right away.

Seems some one posted a one off true Diesel engine a while back.

Hobbsy

My Feedback: (102)

When you consider the early test engines Rudolph Diesel tried, for example feeding coal dust in with the intake air and other fuels, they were all called Diesels even though they did not have any way to inject the fuel. The final product would not necessarily remove his name from the other methods. His research was to find an auto "self" ignition engine that was practical. The model Diesel fits that description perfectly, so in my book the model Diesel is as deserving of the name "true Diesel" as any other.

Motorboy

I am not whole agree with you since i am car mechanic and can tell you:

Rudolf Diesel never wrote it must be injector to be a diesel engine, his goal was to remove electrical spark ignition and glow ignition warmed up with electric glowplug/spiral or torch lamp as semidiesel/hot bulb engine to example (invented of Herbert Akroyd Stuart in 1891) and use the air to raise air temperature with compression and run engine with cheaper fuel to example crude oil, low raffined oil etc.. He had difference solutions how to feed the engine to example use coal powder as fuel when he experimented how to add fuel into the engine either with carburator or injector.

Then the model diesel engine and the real dieselengine will come under the word as compression ignition engine because both engines are using the compresion to ignite fuel with hot air either the engine has injector or carburator.

Jens Eirik

Sport_Pilot

Hey I think the model Diesel's are intresting, and certainly the thing to pick if looking for max torque and low fuel consumption, if not low fuel economy. But if you open any themodynamics book the Diesel cycle is described as a constant pressure power cycle. Gas engines are costant volume by vertue of almost instant combustion. In actuallity the Diesel is not completly constant pressure and Otto is not completly costant volume. The model Diesel engine by the thermodynamics books is constant volume because once ignited there is nothing to prevent it from quickly burning. Doesn't say a Diesel has to have a fuel injector, just the most common way to do this. Now maybe I am streaching the thermodynamics definiton to the real thing, but I think most engineers would agree with me.

gkamysz

My Feedback: (19)

All of the fuel in most diesels is injected before TDC. The constant pressure part of the ideal diesel cycle is combustion. The power stroke is expansion.

http://www.ac.wwu.edu/~vawter/Physic...leEngines.html

I call them diesels because that what they were called when I started modeling. I don't intend to change what they are called. They work well enough for me to enjoy.

Diesel injections systems exist which inject multiple times during combustion. With electromechanical injectors it seems that injector control isn't an issue, yet there are no high RPM diesel engines.




There was also a note about an expansion rate limit for diesel fuel engines, meaning that above a certain RPM you simply get no more power because the volume in the cylinder is expanding too quickly to extract it. I've also read that fuel burn rate is slow, and this also limits RPM. It would take a bit of reasearch to validate some of these things.



Could we build a model size injected diesel fourstroke that would run at 8-10kRPM?

On a side note, I ran a cross a fresh article from Germany that talked about synthetic diesel fuel for vehicles. The goal is reduced emisions. The fuel has a cetane rating greater than 75. Reading about the new low sulphur diesel becoming available int he US now, it has a cetane rating of 55-60. This is interesting by itself as kerosene is much lower than that.


Greg

[email protected]

Greg, I have used syn diesel fuel in one of my late 1940's side port design Oliver Jaguar 2.5 cc engines 2 years ago. I have three of these Jaguars and this is the dog of the bunch and I use as a test engine. I use this engine to test fuels and props. Using fuel that contained the syn diesel fuel the 2.5 cc engine turned an APC 12/7 prop at 5,100 rpm and got 6:09 time on 1/2 ounce of fuel. With kerosene I got 4,900 rpm with 7:51 time on 1/2 ounce of fuel. I had to use a bit more compression with the syn fuel but same needle valve setting. 49% syn diesel, 33% ether, 16% castor and 2% ignition improver. Same percentages with the kerosene based fuel. I warmed the engine up first with a couple of tanks of Olde Engish Mix fuel before trying the 2 special mixes. I then alternated between the mixtures make 3 runs each with syn and kerosene. The rpm and times are averages of the 3 runs for each type of fuel. JackI use this engine to test fuels and props. Using fuel that contained the syn diesel fuel the 2.5 cc engine turned an APC 12/7 prop at 5,100 rpm and got 6:09 time on 1/2 ounce of fuel. With kerosene I got 4,900 rpm with 7:51 time on 1/2 ounce of fuel. I had to use a bit more compression with the syn fuel but same needle valve setting. 49% syn diesel, 33% ether, 16% castor and 2% ignition improver. Same percentages with the kerosene based fuel. I warmed the engine up first with a couple of tanks of Olde Engish Mix fuel before trying the 2 special mixes. I then alternated between the mixtures make 3 runs each with syn and kerosene. The rpm and times are averages of the 3 runs for each type of fuel. Jack

DarZeelon

It is nice to see you attending this forum, Hugh.

Fuel cost is not a fixed number.

As you already know, a model Diesel engine will put out about the same HP as its glow counterpart, at significantly lower RPM, while using about 40% less fuel. Also, with a Diesel, you don't need to invest in glow-plugs, glow-drivers and once you have mastered a good starting procedure, no electric starter (this doesn't go for me; I don't use it for glow engines either...).


Check these out!

MVVS .49 Diesel (an AJC head), normal silencer; Bolly 12.5x6 prop @ 10,300 RPM - 1.04 HP.
OS.46FX glow, normal, un-baffled silencer; APC 10x6 prop @ 14,300 RPM - 1.04 HP.

The exact same HP, yet the Diesel uses half as much fuel; 6 ounces of fuel last nearly 15 minutes at full throttle.

Can you say the same about the OS glow engine?

While the definition of a Diesel engine may say what you wrote; Rudolf Diesel's engines did not comply with them.
It also says, BTW, that a Diesel engine has no throttle...

Sport_Pilot

You are correct I incorrectly called it the power stroke,it is the combustion cycle, however in the ideal (ideal in the since that it is completly constant pressure) Diesel cycle the combustion starts at or after TDC, it cannot be constant pressure if the volume is decreasing. In actual fact no real engine meets the ideal. Nor is the ideal the most efficient. In actual fact in a real Diesel engine the combustion starts before TDC and stops after. In older engines the injector started later and stopped sooner as the throttle simply limited the injector piston stroke. In modern engines the injectors are computer controlled, the timing at idle is set to reduce the Diesel rattle and set for max efficiency above idle.

gkamysz

My Feedback: (19)

Jack, that is some interesting information. I'll have to look around for BTU info of the synthetic diesel. It made about 13% more power but burned 27% more fuel to do it. Have you tried the new low sulphur diesel? Are you buying straight ether in IL somewhere?

Diesel noise at idle RPM is eliminated these days through multiple injections.

But realistcally, I'm not interested in injected engine theory here. If I save a gallon of fuel over the course of a year due to improved efficiency, so what? Fleet operators care about engine efficiency. This is a hobby. I spend money on it to put a smile on my face every once in a while. My father has a '95 Dodge Cummins and gets great mileage. The new ones are even better and much quieter.

What limits RPM of a full size diesel? The only thing I found is that most full size diesel engines have a long stroke and piston speeds limit RPM. Older model diesels had long strokes and were limited in RPM also. Current production high RPM engines have much shorter strokes and are capable fo RPM similar to glow.

Greg

[email protected]

Greg, I used John Deere starting fluid for the ether componet. It is 80% ether and I counted the other 20% of the fliud in the can as kerosene. There is a John Deere dealer in Morris, Illinois. Go to Google and you can find John Deere dealers near you. The syn diesel I purchased a couple of years back has a cetane number of 63 and btu 20,500. Sulfer free and gel point of -67F. The fuel mixture is one I came up with a number of years ago for A Texaco SAM event. RPM is in the 5,000 range and the 16% oil content is OK. Higher RPMs and I would go with more castor oil. Next time we get some 40 degree temps I will try this mix in my Drone diesel with adjustable compression head to see if I get similar results. Jack