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Does anyone know what this is?

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Admiral_dk:
Allan you could look here at Greg's webpage http://www.dieselrc.com/dieselrc.com/engines/ and go down to the Thunder Tiger and see the conversion done with a Tommy Bar (the OS engines above are sligthly different in style).
On this particular subpage (of all Greg's pages) all engines are converted to CI (diesel) - to give you an idea about how minor the looks change outside from the conversion.

dieselpilot:
In a thread on RCUuniverse the "lanova cell" was described as a method to adjust compression in a converted engine. The arrangement is much like a precombustion chamber in an indirect injection diesel. The Lanova Energy Cell was a unique design for IDI where fuel was shot across the combustion chamber and into the precombustion chamber where it ignited and was pushed out to the combustion chamber.

There is a good image near the bottom of this page. https://www.dieselworldmag.com/diesel-trucks/1939-the-first-dodge-diesel/

Allen Smithee:
I took the head off for a quick look and have established a few things:

1. The bore and stroke are 22x26.5mm, which my fag packet says is a nominal 10cc
2. The inner face if the cylinder head is completely flat with the piston sitting at 2mm below the top of the bore at TDC (so I guess the CR is 13.25:1)
3. That device is indeed a small contrapiston - looks like a hardened and ground part about 8mm dia with the lower end machined at an angle so it's parallel to the underside of the head. It has a tiny pin in the side which engages in a slot in the head (that's what I mistook for a blead hole) to keep it correctly oriented. It looks like the total range of movement of the contrapiston is a bit under 3mm upwards.

This detail doesn't photograph well with my phone, so I'll have to dig out my camera (which has a better lens for close-up work) to get some pictures for posting.

I need to find something hardenable to make the rockers from, and I need to do some measurements to work out the geometry so that I can get the curve radius for the tappet face of the rocker where it slides on the valve head. My initial thought is something like 3mm gauge plate or perhaps a bit of 8mm dia silver steel milled to 3mm thick. I guess the alternative would be to just use mild steel and get someone to case-harden (or nitride) the tappet face.

I can't see any way to get lubrication to the rocker bearings, so I feel they should have either bronze or oilite bushes - am I over-thinking this?

AS

Jasonb:
Small ballrace in the end of the rocker arm may solve two of those problems eg hardness and radius, look at Malcom Stride's Bobcat based designs. Or silver solder a piece of silversteel onto the end of a MS rocker and quench as soon as the solder solidifies but still 500deg plus.

It all depends on how much you will run the engine, if it will just be a few odd bench runs to see if it goes then may not be worth the effort, if you intend to fly it that may be a different matter.

Allen Smithee:
That's a good shout Jason - thanks!

I'll measure the cam lifts and get a feel for how much angular movement there will be at the rockers - if there's a lot of angular movement the ballrace option will put a side-load on the valves that could cause problems. But it looks like it would be less of a faff to make.

The head in your photo seems to have no provision for rocker lubrication - do the bronze bushes just run dry or is it a matter of an occasional squirt of oil between flights?

AS

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