Following up on our work to extract everything we can from the reliable, OS .10 engine, we have designed and installed a diesel head. On a 39/39/20/2 fuel, and a 10 X 4 Grish, Tornado prop, we are getting a decent, nearly 10,000 RPM. That was achieved after the clip was taken by tweaking a bit more and getting in more run time. Idle was good at 2,700 RPM but pickup from idle, even a short one, was really, really bad. After the camera ran out, we had to wait a few minutes till the engine came up to speed.
This was unexpected and will need some sorting out. This carb has an adjustable airbleed and the barrel was bored out some.
The irony is that the original, stock throttle worked much better with only the loss of few hundred RPM. The stock carb, it must be said, had no idle bleed hole at all, let alone one that's adjustable. But this IS characteristic of the OS .10 series. They throttle just fine without the need to adjust the low end mixture.
Like the Norvel .074, this is a rarity. MOST engines benefit greatly when you can adjust the low speed mixture.
The rig you see hooked up the the end of the muffler was an attempt to keep combustion products out of some increasingly sensitized lungs. Some 40 years of running these engines has taken its toll. The good news is that it works. Causing nearly no loss in power, the rig has a "smokestack" (out of view) that gets the exhaust up about six feet above the bench. It's adaptable to any engine from a .40 down to the .049s with the use of various sizes of silicone tubing.
What you see dangling below the bracket is an oil collection bottle. The "smokestack" is composed of 6 half litre, plastic soda bottles stacked one on top of the other. This was done to trap all the liquid parts of the exhaust allowing only a dry exhaust to come out the top. As it turns out, much of that liquid is WATER. Well no wonder. The hydro part of hydrocarbon is hydrogen. And when hydrogen burns, it forms water,,, H2O. Neat.
Addendum.
As it turns out, going back to the stock carb and additional testing has revealed that throttling on this engine, as a diesel, is sub par. I tried everything and the only thing that worked was more ether and less kero. I went as high as 60% ether and got close but I gave up. Ether is just too expensive, even on a smallish engine such as this. I may try a two needle throttle.
Here's the interesting thing. I switched this engine back to glow and got the same RPM numbers, on glow, on 25% Cool Power fuel as I did on diesel. But throttling was just as bad. The neat thing about glow is that you can play with compression, nitro content and plug heat range. The first thing I did was to swap out the medium plug for a hot plug. This gave me instant perfect throttling. Nothing else was changed. It appears that changes in heat range on glow has the same effect as changes in ether content as diesel. At least as far as throttling goes.
Loading...
0:59
MP Jets Diesel Hybrid no ether fuel, cold startby hopeso55,481 views
how do you dieselize a engine
swabbster3 2 years ago
You take off the glow head and install a diesel head. This has a piston in opposition to the moving piston. The position of the contra-piston is adjustable with the screw you see in the head, in the video.
You adjust the compression ratio until the diesel fuel ignites by compression alone. From there, as the engine warms up, you continue to fine tune the compression ratio until you get a steady run. Of course the needle valve works in the usual manner.
hopeso 2 years ago
will it work with a regular head i could take the shim out to give it more compression
swabbster3 2 years ago
Fixed compression can work. But the compression ratio required can change from day to day or not be optimum.
Colder weather can dramatically change the required setting. Even a slight loss of the very volatile ether in the fuel can make a big difference.
And taking out the shim won't raise the compression enough.
Go to Davis Diesel Development. They have heads for a hundred different engines. They also sell the fuel.
hopeso 2 years ago
Hello
Allways fun to watch your videoes hopeso.
Congrats on the custom diesel head and the exaust rig. My exaust rig is a hose into a bucket of water.
MuninTech 3 years ago
Thanks,
I had considered that but was concerned about excessive backpressure. Maybe not an issue with the .40 but perhaps with the .06?
In any case, we have further developments, see the addendum.
hopeso 3 years ago