> 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.

[2021] Originally 2333 points and 392 comments:

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

Excellent animations.