Opposing cylinder engine

[Chris Hamel]

I was looking for an idea after completing my last engine and I decided to take a stab at building a two cylinder. For simplicity, I built it with only throw on the crankshaft. In my research I found that opposing cylinder engines were generally built with two throws 180 degrees apart. The crank was built from five pieces which I pinned and loctitited together. I ended up with a little wobble on one end which I wasn't happy with but decided it would still work.

The cylinders are 1 " bore and are made out of aluminum. I used o-rings instead of rings so I figured aluminum would work just fine. Rods were cut on my CNC router and have ball bearings one crank end and bronze sleeves on the wrist pin. Ball bearings were put on the crankshaft as I was assembling it.

The intake valves are vacuum operated. Exhaust valves operate off two cams mounted on a common camshaft. Found out the lobes have to be 90 degrees offset. Had to get creative with one of the rocker arms, but seems to work ok.

I used two ignition modules. The hall sensors are mounted side by side and the magnets are 180 degrees apart.

The carburetor came from an model airplane engine.

I found it runs at a good idle. If I rev it up it wants to walk off the table.

 

[rdean]

Sounds and runs great Chris.
So what is next?

Ray

 

[GL]

Very cool. Bringing all the pieces together to make a running engine from basically scratch has to be very satisfying. I think if both cylinders run on a single crank throw, it’s technically a 180 degree V. If on separate throws, it’s horizontally opposed. VW vs Ferrari V12 - tomato, to-ma-toe. Sounds like you need a 4 cylinder maybe? Or a radial, although water cooling might be interesting.

 

[Chris Hamel]

Thanks for the supportive comments and for understanding what's entailed in building from scratch.