SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Jul 16, 2011, 02:57 PM
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
12,899 Posts
Some of the engines, expecially the Chinese made ones tend to have really large carbs with bores too large to work well. You have to run smaller props to keep the RPMs up so they will be able to draw fuel OK. The problem is aggravated with diesel conversions of course.

I got to thinking that water tends to float with diesel fuel. So any water ought to be on top and not down by the fuel pickup until the tank gets low. Then more current the pump diesel fuels has emulsifiers in it to help keep water broken up into tiny water droplets. Our use of Klotz Benol for castor oil or other brands like it has additives that might help that process too. So maybe it isn't as bad as we might think. But draining and or flushing out the fuel tank from time to time would be a good idea.
earlwb is offline Find More Posts by earlwb
RCG Plus Member
Latest blog entry: My new Gaui X5 Rc Helicopter
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 16, 2011, 03:30 PM
Registered User
Canada, ON, Hamilton
Joined Oct 2005
2,535 Posts
Earl, fill a small clear glass or test tube with water and put a few drops of diesel fuel on the top water surface.
What do you see?
Now shake the mixture up, did you get an emulsion?
Let it stand for a few minutes. What's on top?
If you happen to have methylene chloride (DCM), add a drop; it is denser than water.
It sinks.
John
JohnAV8R is online now Find More Posts by JohnAV8R
Reply With Quote
Old Jul 16, 2011, 03:40 PM
Voices through wires? Ha!
Chas's Avatar
Joined Feb 2003
1,658 Posts
Greg has had great success with his OS Fourstroke conversions, but the venturis are tiny..I think my OS40FS is 3mm ! ...and I know we can get away with the smaller glow sizes like the LA series, so I'm sure you're right about the venturis Earl.
As an aside, Peter Chinn was notoriously down on diesels, partly because of his belief (pessimistic if not downright erroneous) that they could not throttle well. Many a guru has gone against the grain...I remember Clarence Lee was asked how often he had seen corrosion due to nitro, and his reply was a succinct "Never". All part of the fun of messin' around with engines I guess.
JB, your motorcycle diesel project looks interesting...any more details?
Chas is offline Find More Posts by Chas
Reply With Quote
Old Jul 16, 2011, 03:57 PM
Occasional useful idiot...
Joined Nov 2009
1,402 Posts
Quote:
Originally Posted by Chas View Post
Peter Chinn was notoriously down on diesels,
Strange that one, as he is emblazoned on the front of any Model Technics Diesel fuel tin with the words ''Formulation by Peter Chinn''.

Quote:
Originally Posted by Chas View Post
JB, your motorcycle diesel project looks interesting...any more details?
Only in the thread I mentioned earlier. It's a slow burn project (due to severe complete lack of funds and fabrication devices, I have had to farm out all fabrication so far regards the engine and flywheel. Thankfully this has only cost 40 so far and a very generous price from PAW to making me a special 0.21 TBR R/C based on a 0.19. Sadly it appears that I need to get another engine casing or a new engine made as due to trying to figure out how to get this flywheel/clutch assembly to work, the casing was skimmed too thin which has led to it parting company at the spinner end. I now have a free floating engine bearing with just over 1mm of end float on the crank ).

I'm keeping it a secret from most of the bikers (hence my complete lack of posting in there about the subject) until I can get the proof of concept on the track and performing well.

When things are up and running, I will post further results and any relevant links in the diesel oil interceptor thread.
Jonathan Bradbury is offline Find More Posts by Jonathan Bradbury
Reply With Quote
Old Jul 16, 2011, 04:37 PM
kill your idols
ZEROSKIN76's Avatar
utica new york
Joined May 2009
1,819 Posts
Quote:
Originally Posted by Chas View Post
Greg has had great success with his OS Fourstroke conversions, but the venturis are tiny..I think my OS40FS is 3mm ! ...and I know we can get away with the smaller glow sizes like the LA series, so I'm sure you're right about the venturis Earl.
As an aside, Peter Chinn was notoriously down on diesels, partly because of his belief (pessimistic if not downright erroneous) that they could not throttle well. Many a guru has gone against the grain...I remember Clarence Lee was asked how often he had seen corrosion due to nitro, and his reply was a succinct "Never". All part of the fun of messin' around with engines I guess.
JB, your motorcycle diesel project looks interesting...any more details?

the corrosion could be more properly be blamed on the engines owners, including myself. this would be due to improper storage
ZEROSKIN76 is offline Find More Posts by ZEROSKIN76
Reply With Quote
Old Jul 16, 2011, 05:11 PM
Registered User
Gluehand's Avatar
The windy west coast of Sweden
Joined Sep 2008
2,874 Posts
More on water separation:
As a 14 years old, I spent a summer holiday working at a bicycle/motorcycle workshop. There was a kerosene bath (or rather 'varnolen', a closely related naphta product), where oily and dirty parts were cleaned.
About 10-12" from the top of the container was a steel grid, in order to stop parts from dissapearing among the goo at the bottom. The dirt passed the grid.

When cleaning the bath (an obvious task for the youngest employee..), I was taught to first fill water, to just below the grid, then add the kerosene, or 'varnolen'.
As all had 'stabilized', the fluids had neatly separated, water below the grid, kerosene on top.

I'm not sure whether this contributed to the discussion.....just a memory that popped up....



By the way: Model diesels ran great on the 'varnolen' too....
Gluehand is online now Find More Posts by Gluehand
Last edited by Gluehand; Jul 16, 2011 at 05:22 PM.
Reply With Quote
Old Jul 16, 2011, 05:23 PM
Occasional useful idiot...
Joined Nov 2009
1,402 Posts
Quote:
Originally Posted by Gluehand View Post
More on water separation:
As a 14 years old, I spent a summer holiday working at a bicycle/motorcycle workshop. There was a kerosene bath (or rather 'varnolen', a closely related naphta product), where oily and dirty parts were cleaned.
About 10-12" from the top of the container was a steel grid, in order to stop parts from dissapearing among the goo at the bottom. The dirt passed the grid.

When cleaning the bath (an obvious task for the youngest employee..), I was taught to first fill water, to just below the grid, then add the kerosene, or 'varnolen'.
As all had 'stabilized', the fluids had neatly separated, water below the grid, kerosene on top.

I'm not sure whether this contributed to the discussion.....just a memory that popped up....
It contributed all right, and reminds me of my days with the solvent bath!


As earl has run pressurized tanks with no problem and I and others have concluded that water is a heavier element than diesel fuel then it must be a conclusion that it needs to be ascertained
  • How much water by volume as a percentage can a diesel actually cope with
  • How much a diesel engine produces via it's exhaust gasses per volume of fuel/type
Jonathan Bradbury is offline Find More Posts by Jonathan Bradbury
Reply With Quote
Old Jul 16, 2011, 05:25 PM
Dieselized User
gkamysz's Avatar
Chicagoland
Joined Feb 2000
7,325 Posts
Diesels don't need a large venturi, this is true. This is why I don't like some converted diesels. Some carbs are just too large and they simply don't work properly with diesel fuel. Sleeving the carb does work, but virtually nobody does it.

Chas, you have the FS-40 I built? PM me if you want a more practical compression adjuster. That was the first one and I have a better design.

I'm getting ready to make a handful of converted four strokes available.

Greg
gkamysz is offline Find More Posts by gkamysz
Reply With Quote
Old Jul 16, 2011, 05:26 PM
Dieselized User
gkamysz's Avatar
Chicagoland
Joined Feb 2000
7,325 Posts
JB, Don't worry about water in the fuel from exhaust. The volume of exhaust gas that actually makes it into the tank is but a tiny fraction of the total exhaust volume. A better test would be to take a tank full of fuel and add maybe a drop or two of water. I've flown diesels with muffler pressure and never had trouble.

Greg
gkamysz is offline Find More Posts by gkamysz
Reply With Quote
Old Jul 16, 2011, 06:19 PM
Occasional useful idiot...
Joined Nov 2009
1,402 Posts
An interesting observation, and one that seems to be ''true'' due to the fact of the inner diameter of any pressurising tube would be relatively small compared to the exhaust muffler inner diameter thereby passing little of the total volume of exhaust gas to the tank. Which would back up Earl's statement of not having a problem of water in the fuel tank.

When the PAW is up and running again, I will endeavour to give a reasonably accurate figure to the volume of water/oil content of the exhaust gas to try and shed light on it's ratio that is measured direct from the exhaust.

One point strikes me now as I consider this is that when I was 'running in' the PAW with a tube that fed direct from the exhuast into a watering can to collect the oil spray is that I can't really remember seeing any real water content. I will have to test this theorem of course to prove that it is a true and accurate assessment.
Jonathan Bradbury is offline Find More Posts by Jonathan Bradbury
Reply With Quote
Old Jul 16, 2011, 06:33 PM
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
12,899 Posts
Ok you guys are correct, my brain must have been off before I had enough coffee in the morning to get going with.
Diesel floats and water sinks.
earlwb is offline Find More Posts by earlwb
RCG Plus Member
Latest blog entry: My new Gaui X5 Rc Helicopter
Reply With Quote
Old Jul 17, 2011, 01:27 AM
Voices through wires? Ha!
Chas's Avatar
Joined Feb 2003
1,658 Posts
I don't have your FS40 Greg (I WISH !), just my own fourstroke glow.

Fourstrokes are good candidates for dieselization (sic) anyway, with their smaller venturis, but for any given capacity and RPM the two-stroke will pump twice as much air, giving rise to higher venturi velocities and greater latitude with choke diameter...up to a limit, as others have commented. It follows though that the two-stroke will produce more water in the exhaust than a fourstroke, and it is with the large two-stroke carbs that exhaust pressure is most often needed....so there is obviously a "high risk" profile at the top of the power range.
It still comes down to "why bother" with exhaust pressure on diesels, for me though.
Chas is offline Find More Posts by Chas
Reply With Quote
Old Jul 17, 2011, 07:11 AM
Registered User
Canada, ON, Hamilton
Joined Oct 2005
2,535 Posts
Irvine 20, a modern diesel

This example of the Irvine 20 diesel is very modern looking.
I don’t know if it was derived from a glow version and converted to a diesel , or purpose built?
I haven’t stripped this one down, as I got it nib. Looking in the exhaust stack area, one can see that it has very “heavy porting”, certainly not conservative.
It looks more like the .40’s before they changed to the OS “look” and were later made by OS. No pressure tap supplied on this one.
JohnAV8R is online now Find More Posts by JohnAV8R
Last edited by JohnAV8R; Jul 17, 2011 at 07:12 AM. Reason: tap
Reply With Quote
Old Jul 17, 2011, 11:43 AM
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
12,899 Posts
Ok Davis Diesel suggests using muffler pressure too, for those engines that would need it, most likely glow engine conversions.
ref my thread here where I was running a OS 40LA diesel conversion: http://www.rcuniverse.com/forum/m_10..._2/key_/tm.htm

Quote:
ORIGINAL: ddd

Hi Earl,

Their a few reasons why you can't go below 4000 idle. Too much compression, too small a prop and no instructions so you do it the foreign engine way. Your engine will turn a 12X6 APC at 9000 + and idle down to 2000 to 2500. PS always use muffler pressure. If you contact us we will send you instructions. By the way the LA is less powerful then the FP as the LA has no boost port.
earlwb is offline Find More Posts by earlwb
RCG Plus Member
Latest blog entry: My new Gaui X5 Rc Helicopter
Reply With Quote
Old Jul 17, 2011, 12:28 PM
Registered User
Canada, ON, Hamilton
Joined Oct 2005
2,535 Posts
...and if you haven't checked recently....prices have gone up!

http://www.csmodelengine.com/?a=productlist&cid=1

The present diesels appear to be well made, have good fits, lots of compression, and just might be what you are looking for. These are not a 50 year old nib original(s) that just might be frozen/corroded...
If you want a display model, you can't go wrong.
If you are going to run it, then it should be fine.
John
JohnAV8R is online now Find More Posts by JohnAV8R
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Need help with two diesel engines ! cosmin Engines 4 Apr 18, 2014 07:18 PM
Diesel Engines Aeromister Engines 8 Sep 01, 2009 07:17 AM
WTB-Model Diesel Fuel slogo Aircraft - Fuel - Airplanes (FS/W) 3 Nov 13, 2004 09:42 PM
scale model of engines dw1122 Life, The Universe, and Politics 2 Apr 23, 2004 05:43 AM
diesel engines wyflyer_55 Fuel Plane Talk 7 Apr 22, 2002 02:45 AM