# Maybe next model engine HZ opposed twin



## PeterT (Dec 22, 2022)

My 5-cylinder radial is on the proverbial home stretch. More recently finalizing the test stand, glow ignition system, fuel system & seemingly endless remaining To-do list. Don't ask me when prop flip day is - 'soon', the goal posts keep receding. LOL

Anyway, I've also been thinking forward about the next project. There are lots of engines that interest me, but a more logical approach would be something simpler to prove out anticipated issues that would be encountered. I've had these twin plans for a while, its a 60cc horizontally opposed layout, 30cc per cylinder. Not very pretty or scale like, but maybe a good candidate for stated reasons. I finished the CAD work to get a feel for overall design. Its a one piece 2-throw crankshaft which is the bane of model engineers whittling out of solid, getting all the bearing surfaces perfect & mostly minimizing post machining stress relief distortion. Same comment for camshaft plus the added fun of hardening. Camshaft timing is via belt system which is mechanically simpler & maybe advantageous for adjustments. This time I want to make my own piston rings which is kind of a sub-adventure in itself due to heat setting fixtures involved. I'd like to pursue spark ignition / gasoline vs glow plugs / methanol. Spark plus are available in same (1/4-32) thread/size format as glow plugs, that's the easy part. Thereafter kind of a domino effect of related issues - the spark ignition system (buy & fly solid state module vs homebrew-ish distributer, coil etc.). Gasoline can dictate different compression ratio, carb sizing, lubrication, cam/ignition timing. I don't care for the thread-in style of intake/exhaust manifold coupler/tubes on my radial & this engine has the same. I'd like to substitute with bolt-on assembly which sounds straightforward but actually brings up new issues. But this head is bigger & the ports are more spread out, so a good candidate on that basis. Most engines like this get away with oil pre-mix, but real engines have oil pumps. The rear end is relatively open & simple so might be amenable to pump. I'll give this project some more noodling, but it checks quite a few boxes for now.

https://www.cad-modelltechnik-jung.de/construction-plans-model-engines.html


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## Degen (Dec 22, 2022)

One word.

ENJOY!


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## DPittman (Dec 22, 2022)

Very cool.  I think your radial engine project is an amazing work of dedication and superb skill, I'd love to see it someday and maybe even run. Your next potential project sounds just as amazing.  Neat stuff.


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