2-stroke oil as homebrew diesel lube?  
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2-stroke oil as homebrew diesel lube? - 7/26/2005 4:02:42 PM   
Mavi91


 

Posts: 57
Joined: 8/30/2002
From: Oak Lawn, IL, USA
Status: offline 		According to posts I've read, premix 2-stroke oil intended for gasoline can't be used with methanol because it won't mix with it. But what about homebrew diesel fuel? I'm under the impression that kerosene would mix with 2-stroke oil. Is that correct? If it is, would a quality oil intended for non-injection 2-strokes be the best choice?
       Post #: 1

RE: 2-stroke oil as homebrew diesel lube? - 7/26/2005 4:15:33 PM   
SGC


 

Posts: 1020
Joined: 12/8/2004
From: OAKEYQueensland, AUSTRALIA
Status: offline 		Mavi91,
Castor is the best lubricant for diesels , read this :- http://staff.dstc.edu.au/chernich/ron/faq/index.html#qa5
After saying that , good quality multigrade motor oil is also almost as good as castor (10W50)
and I am currently trying a mix of 1/3 Castor, 1/3 motor oil, 1/3 premix aircooled 2 st oil, as the lubricant in my fuel mix. My aim is the Castor and motor oil take care of the extreme pressure lubrication and the detergents in the motor oil and 2 st help keep the insides free from carbon. The 2 st oil also has anti knock qualities which may /maynot help.
I personally wouldnt run a diesel on less than 1/3 - 1/2 of the oil as castor. jm2cw
Stewart

< Message edited by SGC -- 7/27/2005 2:35:22 PM >

(in reply to Mavi91)
       Post #: 2

RE: 2-stroke oil as homebrew diesel lube? - 7/26/2005 6:47:37 PM   
Motorboy



Posts: 1629
Joined: 2/7/2004
From: Bergen, NORWAY
Status: offline 		I will strongest not recomment the pure 2 stroke oil to the modelengines cause too low viscose and too thinn oil to prevent leakage. I am using pure 4 stroke oil 10W40 or 20W50 or similar to moderate dieselengines and pure castoroil to hi-power dieselengines.

Jens Eirik

_____________________________

Jens Eirik
All landings are just controlled crashes!

(in reply to SGC)
       Post #: 3

RE: 2-stroke oil as homebrew diesel lube? - 7/28/2005 2:36:20 PM   
gtutmark


 

Posts: 9
Joined: 12/16/2004
From: camano island, WA, USA
Status: offline 		i have been using MAXIMA 927 motorcycle pre-mix castor oil in home-brewed diesel fuel for years with no problems -
other motorcycle premix castor oils that would work just as well are BLENDZALL GREEN LABEL AND DUMONDE TECH -
i also use jet A for the fuel and Thust brand starting fluid (for ether) or pharmacy ether (i couldn't tell any difference between the two in starting and/or running)
greg

(in reply to Mavi91)
       Post #: 4

RE: 2-stroke oil as homebrew diesel lube? - 8/1/2005 3:43:50 PM   
Mavi91


 

Posts: 57
Joined: 8/30/2002
From: Oak Lawn, IL, USA
Status: offline 		Gtutmark:

Out of curiosity, do you treat the total volume of the starting fluid as ether?

Thanks...

(in reply to gtutmark)
       Post #: 5

RE: 2-stroke oil as homebrew diesel lube? - 8/2/2005 2:04:56 PM   
gtutmark


 

Posts: 9
Joined: 12/16/2004
From: camano island, WA, USA
Status: offline 		surprisingly, yes - i've heard that the brand i use (THRUST) is something like 80% ether, so i'm pretty close - but then i use the tried and true 1:1:1 mix, so a few percent points one way or the other with the ether is no big thing and i also prefer to avoid nitrate additives - after my very good ED racer corroded itself into uselessness, i blamed residual NOx for creating badness leading to acids (which, last time i checked are BAD juju)
greg

(in reply to Mavi91)
       Post #: 6

RE: 2-stroke oil as homebrew diesel lube? - 8/19/2005 4:08:53 AM   
Mavi91


 

Posts: 57
Joined: 8/30/2002
From: Oak Lawn, IL, USA
Status: offline 		A follow-up: I brewed up a mix of 35% starting fluid, 25% 20-W50 oil and 40% kerosene, got a JRL conversion head for a good running OS .40 FP and tried it out. The starting fluid was Pyrol brand and I don't know what %ether it has. The engine is starting well and running much cooler than it did on glow fuel so I'm guessing there's enough ether. Since I've never owned a diesel or even seen one run, I had a few questions, however. Am I doing things correctly?

What I did: The conversion head came with the contra-piston all the way out (low compression). I found the starting point by removing the muffler and putting a few drops in the exhaust port and cranking with short bursts of the electric starter. I repeated this process, raising the compression until it fired and then attached the muffler, hooked up the tank and set the needle valve at about 2/3 of the glow level. The tank was set up with muffler pressure.

The engine started and ran on the first try. I let it come up to temperature and then reduced compression a little and refined the needle valve setting. Then I alternately raised compression slightly and reset the needle valve. I continued this as long as the speed increased. I stopped the compression increases when a further increase caused the engine note to flatten and the rpm to decrease. I then reset for best speed. The needle valve setting is well defined and easily set; it stumbles if too rich and misses if too lean.

Running a 10-6 prop I get reliable idle at about 2,200 rpm and top speed of 9,200 rpm. The engine loads up a little if left to idle for a long time but otherwise responds ok to a sudden throttle increase. At roughly 1/4 throttle I get an exhaust note that sounds almost like a large diesel engine at idle. The exhaust note smooths out as speed increases and seems to have a "sweet spot" at about 3/4 throttle. At full throttle the exhaust note sounds sort of like a glow engine running too rich. . .although the needle valve behavior is as described above.

Is the performance and behavior I am getting correct? I had expected to see a somewhat higher rpm with the 10-6 prop, although I'm not disappointed given the easy starting and clearly defined responses to my adjustments.

Finally, thanks to all for your help. . .I'm having a great time with this!

(in reply to gtutmark)
       Post #: 7

RE: 2-stroke oil as homebrew diesel lube? - 8/19/2005 6:28:22 AM   
SGC


 

Posts: 1020
Joined: 12/8/2004
From: OAKEYQueensland, AUSTRALIA
Status: offline 		Mav,
A better method to adjust a diesel is :-
After warm up , back off the compression till it shows signs of undercompression , ie burp burp sound. Then increase the comp till it smooths out.
Adjust the needle for best running /throttle response.
Repeat this to or more times to refine the settings.
Doind as you say it is easy to overcompress, with an over rich needle covering up the overcompressed condition .
Also as you are not useing ignition improver, high rpms may not be acheiveable due to ignition lag . Try a 12X6 prop with your fuel , or even a 12X8, the rpms shouldnt drop of much but the thrust will increase.
Note the compression and needle will need reseting with each prop change.
Stewart

(in reply to Mavi91)
       Post #: 8

RE: 2-stroke oil as homebrew diesel lube? - 8/19/2005 10:42:36 PM   
Mavi91


 

Posts: 57
Joined: 8/30/2002
From: Oak Lawn, IL, USA
Status: offline 		Stewart,

Your diagnosis was correct. I added about 1.5% MEKP and was rewarded with a 1,000 rpm increase to 10,200 on the 10-6 when I reset the compression, etc. Much smoother runniing as well, although the exhaust note was still a little off-sounding to me at full throttle. I had a 12-5 prop on hand and tried that as you suggested. That further smoothed out the top end and seemed happy running at 8,400 rpm. At 6,000 rpm it now sounds very much like the bark of a 4 stroke. Throttle response is crisp. Idle is very smooth.

Since I haven't seen or heard a diesel before I must admit I'm still concerned about potentially overcompressing the engine. How can you tell? As I have the engine set up, the exhaust stream isn't even warm at full throttle. I can touch the muffler briefly while running without getting burned, although I wouldn't want to leave my finger there for longer than a touch. With extended running, the exhaust note/rpm didn't change. I did try cranking in the compression past the smooth running point and could hear the exhaust note get flatter and the rpm drop. Is that what overcompression sounds like?

Thanks for your help.

(in reply to SGC)
       Post #: 9

RE: 2-stroke oil as homebrew diesel lube? - 8/23/2005 1:52:07 PM   
gcb



Posts: 2340
Joined: 10/24/2002
From: Port Ewen, NY, USA
Status: offline 		Mavi91,

If you want to use Amyl Nitrate instead of MEKP (less corrosive?) you can get it from Eric Clutton (Dr. Diesel).

Running over compressed is equivalent to timing a spark engine so it runs too far advanced. It causes pre-ignition which increases temp and stresses parts.

The decreasing compression and increasing until it smoothes out is a standard diesel procedure and works well. Make sure your final adjustments are not completed until your engine gets up to normal running temp.

Good luck with your diesel conversion.

George

(in reply to Mavi91)
       Post #: 10

RE: 2-stroke oil as homebrew diesel lube? - 10/6/2005 11:15:01 PM   
AndyW


 

Posts: 1890
Joined: 1/17/2003
From: Timmins, ON, CANADA
Status: offline 		I just tested, on my Norvel .074 conversion, a mix of 25% JD ether, 50% kero, 25% 50 weight, non-detergent motor oil. Also, 2% Amsoil cetane booster was added.

The engine started, ran normally, top and bottom ends were the same as my castor mix and throttling remained very good.

I don't know how well the motor oil will protect the engine, so I'm going to fly that mix exclusively on this engine till something bad happens,,, or doesn't happen.

If it works out well, I'll have a mix that allows me to get all the ingredients locally, on demand, without having to wait for the mailman. The Amsoil was ordered on line, was cheap and at 2% usage, will last a long time. MEKP will be used in a pinch.

With no hobby shops within 200 miles, flying diesel becomes less of a hassle than glow, as I can get fuel any time I want.

_____________________________

Andy Woitowicz

(in reply to gcb)
       Post #: 11

RE: 2-stroke oil as homebrew diesel lube? - 10/22/2005 6:09:56 AM   
Motorboy



Posts: 1629
Joined: 2/7/2004
From: Bergen, NORWAY
Status: offline
quote:

ORIGINAL: gcb

Mavi91,

Running over compressed is equivalent to timing a spark engine so it runs too far advanced. It causes pre-ignition which increases temp and stresses parts.

George


Yes and the engine will lost max revolution or oscillate if overcomressed.

Jens Eirik


_____________________________

Jens Eirik
All landings are just controlled crashes!

(in reply to gcb)
       Post #: 12

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