gkamysz

My Feedback: (19)

I was searching some MSDS for starting fluid and the only one I found for JD RE33636 said it was 46% ether or 67% of non propellant conponents. It is strange as the can says 80%.

After searching several MSDS it looks like they are inconsistent. Prestone said it had 40-70% ether in one sheet. I did find a manufacturer in Wheeling that makes a 70-80% ether fluid. Have you ever seen Penray or Super X starting fluids in the store? I sent an email asking for retail sources.

Greg

the bob

has anyone ever been to a constuction site where a diesel pile drive is being used? they lift the piston up and a trip lever drops it into a cylinder mixing fuel and air then KOPOW. its only a big diesel engine.

Mavi91

I have noticed that some auto starting fluid msds sheets report ether content by weight, while most of us mix our fuels by volume...I'm wondering if that's the cause of the differences. I do get OK performance out of Prestone, but keep wondering if John Deere would work better as I feel that I need more compression than I should have to use. I haven't had a mechanical failures yet, so maybe that's not a problem.

Usually, the additional contents in the can of starting fluid is hexane. I'm guessing that there isn't as much energy in it as kerosene.

I'm also in IL but a drive to Morris is a long way for me. Wheeling would be better, so holla back if you find that high percentage stuff.

Sport_Pilot

Although modern and smaller Diesel engines can turn much faster RPM the Diesel engine turns slower because fuel burns slower, and being injected over a period of time also slows down the burn time. This limits maximum shaft speeds. The long stroke is only a function of maximizing one of the Diesel engines strong points. In general gasoline engines with long strokes turn higher shaft speeds than Diesel engines.

DarZeelon

Hugh,


While this may be a partial truth with full size Diesel engines; it has little to do with model Diesel engines. Partial, among other reasons, because modern common-rail Diesels have a very short injection duration (at extreme pressure; 1,000-1,700 Bar)

In a model Diesel, the fuel is all there before compression has started and it all ignites, within the whole combustion chamber, as soon as the compression built temperature exceeds the di-ethyl ether component's flash-point.
The burn is over and out within a millisecond. The flame-front does not need to propagate anywhere.

One of the reasons glow engines are generally more noisy than model Diesels, is that in a glow engine, the burn is still in process, when the descending piston unmasks the exhaust port.
So the glow engine emits actual combustion noises; not only residual combustion pressure release noises.

If you run a glow engine at night, with an open exhaust, you would see the flame.

A Diesel runs dark.

As to RPM, team-race C/L Diesels run at very high RPM.
We tend to prop converted Diesels with large props, to exploit the higher BTU value of model Diesel fuel and their increases torque. But in general, they can theoretically run as fast as the glow engines they were, before the conversion.

...And, a long stroke (under-square, actually) engine does not have any torque advantage over a short-stroke (over-square) engine.

It is no more than a buzz-word.
With all timing numbers being the same, an under-square engine will likely have its RPM of maximum torque reduced. This would, in theory, allow it to spin a larger prop at a lower RPM.

But theory is theory. The real torque paragons are big-bore engines, like the MVVS .91...
An over-square engine...

Sport_Pilot

Dar,
I was not discussing model engines, I was replying to a discussion about full scale engines. I should also point out that the increased compression increases torque, but it also does not significantly inhibit engine speed.

Sport_Pilot

Which is why I mentioned that modern engines turn higher speeds. What part of ---- ? Oh never mind!

Sport_Pilot

...And, a long stroke (under-square, actually) engine does not have any torque advantage over a short-stroke (over-square) engine.

It does in a Diesel. More verticle area for the injection spray and burn. More torque on the crankcase for the higher compression ratio.

It is no more than a buzz-word.
With all timing numbers being the same, an under-square engine will likely have its RPM of maximum torque reduced. This would, in theory, allow it to spin a larger prop at a lower RPM.

Generally over bored engines have more area for intake valves and ports.

Hobbsy

My Feedback: (102)

Lets keep this to an RC Diesel discussion please

Sport_Pilot

Ok, but it all started about someone making a true injected model Diesel, one which would run on #2 fuel oil. If one wanted to build one, then an understanding of how they work would be in order.

donkey doctor

Hello; Dar, after reading your post, I noticed a few things. You state that as soon as the pressure reaches ether's combustion point, it's all over, if that was true, why is there kerosene in the fuel? Secondly about long stroke engines and torque production; a longer stroke means that the crank has a longer arm, and therefore more torque then a shorter arm (all other things being equal (which they never are )). Granted a bigger bore makes more room for bigger valves, and better breathing, but a longer arm is a longer arm.

SGC

Re torque, yes it is true a long stroke diesel will have greater torque at a given RPM , but total/ max torque is totally different this is dependent on how efficient the motor is overall, ie how well its designed /built. Many over sq motors produce huge amounts of torque / horse power be it at higher RPM's, this is true be it full sized or model motors 2 and 4 st.
DarZeelon, re the combustion duration , this depends on fuel quantity ingested/injected open the needle up and you will get more noise and flames, on full sized diesels set for max power it is common to see flames out of short exhaust systems whilst under load, my own Ford tractor(mk2 Ford 5000, most powerfull 4cylinder non turbo Ford made) when pulling hard has 6" of orange flame out the top of the exhuast stack at night.
Stewart -diesel fitter, MIAME

DarZeelon

Doctor,


Please re-read that post of mine.

When the ether flashes it ignites all the other fuel components, including the kerosene, which is the fuel's main source of BTUs.

Are you not forgetting something???

When for a given displacement you use a longer stroke, something must become smaller, so the displacement would not increase.
This something is the area of the piston top, or half the bore squared, times 'Pi'.

So yes, the pressure is the same and it is applied through a longer arm; great until now. But the combustion pressure is applied to a smaller area, so the force is smaller.

The smaller force, applied to the longer arm does not make 'more torque', does it?

If the bigger bore would only make more room for bigger valves, you would be right...

gkamysz

My Feedback: (19)

Ether has a low heat content 15,000 BTU/Lb(still 50% better than methanol) and is expensive. Ether alone wll run a diesel engine just fine, but makes little power and would go through a tank of fuel pretty quickly. Kerosene has a higher heat content at around 24,300 BTU/Lb. Kerosene won't self ignite at the compression ratios we operate at. Ether does self ignite, so a certain percentage of ether is used to initiate the combustion at a reasonable compression ratio. When the ether ignites, the kerosene goes with it. Kerosene is cheap, so a mix of these two components makes for a handy model diesel fuel.

I was thinking along the lines of Dar. That the ether setting off the fuel oil allows much higher operating RPM in model diesels than in injected diesels.

I read somewhere that the stroke is not particularly responsible for the amount of torque an engine makes. If the engine is over square there is much more piston area to transfer pressure in the cylinder to the rod. Full scale diesels tend to have long strokes because of the requirement for low RPM due to the way the fuel burns. Low RPM engines must make lots of torque to make a decent amount of HP. HP is what does work, torque alone is useless.

Greg

Motorboy

We need ether because ether has high cetane number between 80 and 90 while autodiesel has cetane number between 45 and 50 therefore the ether will ignite at low compression.

Jens Eirik

gkamysz

My Feedback: (19)

Jens, is that not what I wrote?

SGC

A little more on torque, a long stroke motor in general has a higher volumetric efficiency( design dependent). they also tend to have a flatter torque curve which makes the horsepower more useable. Now adding on , modern diesels have better injectors which enables faster burn rates makeing high horsepoer over square engines possiable, more and more automotive diesels are being run at similar RPM's as petrol ie 6,000RPM range.
The arguments are becomeing more clouded as new developements are being made.
Back to models , as stated befor there are many high RPM model diesels and these are both over and under square, port timeings, general design features and construction make the difference.
Stewart

SGC

Another of the mystery ENYA 40 4st Diesels for sale :- http://cgi.ebay.com.au/ENYA-41-4C-DI...QQcmdZViewItem
Did Enya give up on these ??????
Stewart

Hobbsy

My Feedback: (102)

I do not see where that is a Diesel. There is no Lavona cell anywhere to be seen, it has glow plug in it.

AMB

Quite strange the box has a black label stating diesel looks just like the one my 25 2stk came in whats in the parts bag? hard to believe\its a do it your self conversion that would not be an Enya thing and it sure is a glow plug and a diesel instruction sheet
martin

Sport_Pilot

A rip off tactic is using the wrong box and instructions for a higher priced product.

Jim Thomerson

That doesn't look like any glow plug I know (which is not all of them by any means). I haven't bought an new Enya in years, but they used to come without glowplug. All very interesting.

Hobbsy

My Feedback: (102)

Jim, it's identical to the ones that came in my .46, .53 and 1.55.

DarZeelon

Jim,


Enya glow-plugs do have an unusual appearance, with their large central terminal.

See photo.

injunnut1

What is a lavonia cell ..... 'lavonia' not in my dictionary except as a City in the State of Georgia (USA) ????????