Worth noting the design of the internal combustion engine hasn't changed much in 50 years.

The thing that has changed is the control systems.

What used to be a primitive mechanical way of mixing fuel and air (the carburettor), is now an electronic fuel injection system, with the fuel air ratio very carefully matched to reduce pollution (fun fact: modern cars release so little carbon monoxide, you won't kill yourself by starting one in a garage (but don't try it just incase your car is faulty)). Catalytic converters use any tiny fuel air imbalance to reduce carbon monoxide and soot, and on the other side nitrous oxides, by slightly increasing and decreasing fuel air ratios.

> Presence of oil is critical here as it creates conditions for hydrodynamic lubrication.

You can hear this effect in some vehicles at initial startup time for a few seconds. I know of certain Ford engines where it actually causes issues over time. The model years with auto start/stop have the worst of the cam rattle disease.

The thing that's missing here that really drastically changes the story is all the emissions control hardware that would exist on such an engine.

This is a circa 1990s engine in the US market i think? Dual Overhead Cam didn't really become popular in the US market until then i think. 70s-80s for single overhead cam to become established.

The diagrams are beautiful and informative as always from this author.

"in real running engines the rotating crankshaft should float completely on a very thin surface of oil" - I found this to be a great insight.

Pro tip: Show a message if WebGL is disabled instead of a blank space.

Wonderful but it irritates me that so many descriptions of internal combustion engines refer to "explosions" of the fuel. You don't want that. It causes knocking and pinging and engine damage. You want a controlled burn that generates heat smoothly.

Very interesting technology. Would be exciting to see a hardware startup build a product around this.

[2021] Originally 2333 points and 392 comments:

https://news.ycombinator.com/item?id=26991300

If you like this kind of stuff go and look up videos on the Rolls Royce Crecy engine from WWII. Absolutely insane engineering that died due the dawn of jet propulsion.

Excellent animations.

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