Jetdesign

My Feedback: (8)

Hello,
I want to run an RC plane engine on biodiesel. Where can I get either a diesel head or directions on how to make one? I don't have an engine yet, so it doesn't have to be brand specific.

Thanks.

LeeHop

Take a look here: [link=http://www.mecoa.com/acc/diesel/index.htm]Mecoa conversion heads[/link]

Jetdesign

My Feedback: (8)

thank you.

AMB

Mecoa has 2 the .049 cox type and a 40. Davis Diesel makes a very wide assortment. martin

greggles47

Gar,

Why not buy a diesel motor to begin with??

You are then sure that the motor is engineered to withstand that additional stress of diesel combustion.

Regards


Greg

AMB

Greggles good point the only available in the USA is PAW, He would have to order say Enya or there may be some MVVS 61s from overseas, If he has some glows around he might find
a head from davis he could convert just for the price of a head. I have mostly Davis conversions but do have MVVS, PAWs and Enya diesels martin

Ployd

Hi Gang

I think you missed the opening sentence of garcfield's post in that he wanted to run his engine on bio diesel. We all know that our model diesels will not run on biodiesel alone nor satisfactorily when mixed with traditional ingredients (ether and castor oil) so suggesting sources for heads becomes a moot point.

Garcfield, the suggestion put forward by Greggles and AMD is the best and most practical course to take and forget bio diesel, contrary to what some may say.. it's a dead end for our purposes.

Ployd in OZ

AMB

GaRc field So far Biodiesel for our purposes has a way to go Mr Davis has a couple of heads out to a University, so far not fruitful. Our standard Ether, Kero ,Castor or syn/castor blend still the best after 60 years or so martin

greggles47

For Enya Diesels - check
http://www.enya-engine.com/ListDSL_E.html

Hobbsy

My Feedback: (102)

GA, I have Irvine, K&B, Fox, OS, Webra, SuperTigre, MDS, MVVS engines converted to Diesel operation. I have also run a couple of fourstrokes on Davis ABC mix with no ill effects. The additional stress everyone stresses simply does not exist except when someone overcompresses the engine. If you want to try a simple, easy to set up and powerful engine get an OS LA .46, it will purr like a kitten and turn a Graupner 12x7 in the mid nines and sound relaxed doing it. If you prefer a ball bearinged engine a Fox .46 or SuperTigre .51 are excellent choices also. The Irvine .53 is the king of the .45 to .50 sized conversions but OS has put MickeyMouse carbs and mufflers on the Irvines as well as changed the liners to ABN plus changed the bore and stroke to suit their current maccining operations.

bogbeagle

Hi,

I have recently converted a ST .75 to diesel and am surprised at how well it runs..and how easy the conversion is.

I'm gradually tinkering; out of interest. But, do you think that there is any advantage to using a carb with a smaller bore than the standard ST item? I seem to recall that this will improve throttling and idle at the expense of top-end? Any experienced guys out there?

BTW, the ST.75 swings a Graupner 15 x 8 at 6,200/1800...rock-steady idle and pick-up. Gonna try a smaller prop, but the Graupner was handy. Will source a 14 x 7 tomorrow and experiment some more.

I'm hoping that it will be possible to dispense with the compression adjustment apparatus and operate with fixed compression. This works fine on the Enya 40 four-stroke, so I can't see any reason why it wouldn't work on my ST .75. What do you think?

Patxipt

Bob, reducing the carb throat will help it run better, as at roughly 75% the glow carb maxes out as a diesel, no point in running it more open.
Running it as a fixed compression diesel will make you have to fiddle when prop or weather conditions change. You will then need to find what the best fuel mixture is for the ocasion. Having variable compression lets us vary the loads imposed on the engine, cope with the varying weather, etc, without much trouble.
Keep in mind the Enya four stroke diesel makes use of several head shims to crudely vary the compression when needed by taking or placing the shims.

gkamysz

My Feedback: (19)

Do you have an Enya 41-4C that works OK as shipped? Are you happy with the piston to cylinder fit? I know it's shipped without compression adjustment, but I find diesels still need minor compression adjustments day to day.

mike109

G'day I have a Magnum 46 converted to diesel and I could not get it to throttle on its original carby so I put the carby from a GMS 32 on it and on this is works very well. The 32 carby is quite a bit smaller in the throat. I bought the diesel head about 16 years ago with an ASP 46 Mk 1. It too ran well but would not throttle. I had plans to reduce the size of the throat but sold the engine and kept the diesel head until recently I just had to find out whether it would work. I bought the Magnum on a certain auction site cheaply. It was a well used example but with excellent compression. I saw that Hobbsy had been using a 12 x 7 prop on his LA46 conversion so I tried this on the Magnum but it was simply too much for this engine. It works much better with a lower load and higher revs on a Bolly 11.5 x 5. It hauls my Great Planes Big Stick 40 around really well.

The picture shows the engine with its original Magnum carby.

bogbeagle

The Enya 41-4c diesel works pretty well, as it comes, I find.

After a prolonged idle (5 minutes, or so), it sometimes gets a little chilled and might splutter on pick-up for a few seconds until it warms up. I am very impressed by this engine. It isn't overly powerful, but it is incredibly reliable. I've flown it for quite a few hours, now, in a Ready 2 (just about adequate power) and it has never come close to quitting.

In fact, it's a bit of a party trick to leave the engine, purring away at idle, for prolonged periods. Glow flyers are just amazed that it keeps running and then picks up when the throttle is opened.

When I first got the motor, my friend and I told the other flyers that we had imported some "special" glow plugs which needed no external power supply...and that this was the reason that the engine could be started with no apparent electrical connection to the plug. A surprising number of people fell for this story; most of the flyers at our patch have never seen a diesel engine or smelt diesel fuel.

Of course, one or two of the older guys quickly sussed us. Pity,really, we could have made a fortune in advance orders for our "special" plugs at £15 each.

Someone mentioned the low compression ratios which are all that is required to run diesel. My experiments with the ST confirm this...to my surprise. I have plans for more diesel conversion, if the ST lives up to its initial promise.

Will try that smaller bore carb on my ST conversion. Results to follow in a day or two, I hope.

[email protected]

Bogbeagle, I have no experience with four stroke glows, spark or diesel. I do have an OS .20 four stroke that I have not run. Reading about the Enya four stroke diesel I see it comes with out the valve cover or push rod tubes installed. Do you run yours with out the valve cover? What is the purpose of the push rod tubes? Could you run the engine less the push rod tubes? jack

bogbeagle

I run my Enya with both the rocker cover fitted and the push-rod tubes fitted.

AFAIK, the push-rod tubes perform little purpose except to reduce the ingress of dirt into the engine. Lots of early 4-strokes were not even supplied with push-rod tubes. Some model engines are still supplied with "open" pushrods. There is no requirement to use these tubes when running the engine.

If rocker cover' clearance is a problem, you could make a thick gasket from a bit of card; so as to avoid any possibility of the rockers tapping on the inside of the rocker' cover.

bogbeagle

OK. I ran my ST .75 today....using a small-bore carb.

Results; no difference in top-end or idle rpm, but smoother transition and pick-up. Very pleased with this conversion. That idle is rock-solid. I left the engine ticking over whilst I brewed up and had a coffee. On my return, the rpm hadn't changed by a whisker and the pick-up to full power was excellent.

This will make a good engine for my Flair Fokker DV11, when I get around to building it.

With the large prop, 15 x 8, the ignition timing does not vary greatly throughout the rpm range (4,400rpm range). So, I could now blank off the compression adjustment facility....so long as I stick with this size of propeller.


Meanwhile, I shall see whether I can cadge a hack airframe from a mate of mine. Something like a trainer or Limbo Dancer would be OK. That can be fitted out with the ST .75 and the engine tested in flight.

I'll probably experiment with one or two more props, though. So, for now, the engine will retain its compression adjustment screw. Actually, although I stated that the smaller carb had no effect upon the tick-over, that isn't quite true. I was able to reduce the tick-over by 100 rpm to just 1,700, but I couldn't honestly state that this would have been impossible when using the larger bore carby. There are just too many variables.

DarZeelon

Quote:

ORIGINAL: gaRCfield

Hello,
I want to run an RC plane engine on bioDiesel. Where can I get either a diesel head or directions on how to make one? I don't have an engine yet, so it doesn't have to be brand specific.

Mr Field,


You cannot!

BioDiesel fuels, while being made from oil wastes, behaves like ordinary Diesel fuel, like the type used in nearly all trucks, tractors and a few full-size cars too.

This means the compression ratios needed are 20-22:1 in older pre-chamber type Diesels and ~18.5:1 in modern, direct injection Diesels.


Model Diesel engines have compression ratios that are comparable to low-nitro glow engines (around 10:1), which means they cannot even come close to combustion chamber temperatures needed to ignite Diesel fuel in general and particularly bioDiesel.


This is the reason converted glow engines (and proprietary model Diesels), need a fuel that contains the very volatile substance; Di-Ethyl Ether...

This component of the fuel self-ignites at temperatures achievable, even by the low C/R of our engines.


So, if you do want to use bioDiesel, it can only replace a part, or all of the kerosene/parafin component of the model-Diesel fuel.

And even then, it must be fully miscible in Di-Ethyl Ether and in castor oil (and DII too)...



I believe a few did try to use normal Diesel fuel instead of kerosene, but I cannot recall their success rate...

Even then, you would be saving very little...


And, if you insist on raising the C/R enough to run bioDiesel... be sure to buy a large stock of crankshafts and con-rods, that you will need to replace those that break apart/bend every couple of days, more maybe...[:@]

gkamysz

My Feedback: (19)

Dar, what experience do you have or research have you done with No.2 fuel oil(pump diesel) or biodiesel? No.2 is much closer to kerosene than it is to biodiesel. Attempting to replace kerosene with biodiesel will not yield the results you are expecting. However, if you have done some testing we'd all like to read about it.

gkamysz

My Feedback: (19)

http://www.biodieselnow.com/forums/p/1952/7463.aspx

If you scroll down to toward the bottom of this page you'll find a comment from a familiar individual. Where is the bio blend fuel? I don't see it on the website.

Here's another interesting link.

http://journeytoforever.org/biodiese...cle.html#tinyd

Mind you, I don't approve of running biodiesel in a model engine, but you're free to try.

DarZeelon

Quote:

ORIGINAL: gkamysz

Dar, what experience do you have or research have you done with No.2 fuel oil(pump diesel) or biodiesel? No.2 is much closer to kerosene than it is to biodiesel. Attempting to replace kerosene with bioDiesel will not yield the results you are expecting. However, if you have done some testing we'd all like to read about it.

I am sure you all want to know and yourself in particular... But I have never done this...
BioDiesel is not commercially available in Israel and I know no-one that actually makes any of it by himself.


In my post, I wrote about reading a thread in the forum, where someone experimented with Diesel replacing kerosene, in his model Diesel fuel mix...

I did not find this thread, but it was previously to you beginning to be very active in the Diesel forum.

gkamysz

My Feedback: (19)

Dar, we had members running it recently. You must have been absent that week of diesel school.

http://www.rcuniverse.com/forum/m_60...6056269/tm.htm

http://www.rcuniverse.com/forum/m_6511931/tm.htm

Jim Thomerson

I wonder if the way to go with biodiesel is to run it in a glowplug engine with a flight pack keeping the plug hot.

gkamysz

My Feedback: (19)

The big problem with biodiesel is that it begins to boil at ~400°F. The vapor pressure of biodiesel at room temperature is nil. This is fine in a full size diesel because the air is heated to well over 800°F and the fuel is atomized through an injector nozzle. We don't have either in a model engine and this is why it doesn't burn well.