Opposing piston engines.

[spikerS]

TIL that there is such a thing as Opposed Piston engines. I don't know why I didn't think of this sooner.

Just wondering, I can only seem to find references to diesel examples, but are there any gas-powered ones?

These are supposed to be crazy efficient, and way more reliable than their traditional piston/cylinder head counterparts.

A video describing what one of these engines are:
UF5j1DvC954

I get it that these won't be crazy powerful engines, powering exotics, but with CAFE standards and such, wouldn't an engine design like this powering small commuter cars do amazing in a manufacturer's fleet of production vehicles?

[BerserkerCatSplat]

It's certainly got downsides. Twice the number of rotating components as a conventional design (two crankshafts, two pistons per cylinder, etc.). That also means that each cylinder assembly takes up twice the volume of a conventional engine - so now you have to try to shoehorn an engine that's volumentrically basically twice as large into a standard engine bay - and not to mention that the size difference is primarily height, so now your engine is tall as fuck and good luck getting that into an engine bay while meeting pedestrian crash standards.

It's also a two-stroke, so it may have difficulty meeting emissions standards as well.

[revelations]

I dont know about the automotive industry, but I am a bit surprised that for eg. the shipping/rail industry has not developed any of these alternate piston engine configurations into something super efficient. I'm guessing that the existing systems are so well integrated (heat recovery) that there might not be the financial/technical incentive enough to warrant a complete rethink of piston engine working.

Also the fact that the larger engines run on essential waste oil products, probably has a lot to do with it as well.

[AndyL]

why not - in simple terms - harmonics.

2 crankshafts are a fricken bitch when it comes to torsional vibration.