What do people think of these new engine designs?

[Jmoan]

https://www.youtube.com/watch?v=bBrUrgNf5y8

Number 6 looks good but I think it would leave a mess on the inside unless it ran on clean gas.

[Easy-X]

5Nm ion-thrust engine... that's revolutionary for spacecraft. The rest... meh
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Sister Sledge]

Most have their origins way back in time. The opposed pistons for example - Comma? did them and Leyland too?
What we're seeing is older ideas put to working more efficiently because we're able to electronically monitor the systems on them better.

With that chainsaw motor it's just that - a motor turned by air. I doubt it could be put to being internal combustion? It appears to have lubrication issues for a start and where a lubricated air supply would come in.

We've seen some incredible engine designs mind. I like to drool over an old aircraft radial engine or marvel at the accuracy and size of a marine diesel.
True this: I once drove an opencast mine dump truck (with permission but shouldn't have!) which was the size of a bunch of houses. I swear that I could feel the power strokes on the pistons in that engine!
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CCM 404 DS