▲Internal Combustion Engine(ciechanow.ski)
137 points by StefanBatory 5 hours ago | 10 comments
▲bob1029 1 hour ago
> 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.

▲Toutouxc 23 minutes ago
Note that that sentence is talking about the crankshaft bearings and their hydrodynamic lubrication, which is, well, elsewhere and separate from any cam rattle issues (including the cam phaser oil starvation that you might be referring to).
▲culopatin 3 minutes ago
Lifters also often drain while sitting and valve lash is greater at start until they get slapped a few times
▲CraigJPerry 1 hour ago
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.

▲MarkusWandel 36 minutes ago
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.
▲Toutouxc 9 minutes ago
Not exactly. You do want a deflagration and not a detonation, but "explosion" is more loosely defined and, depending on who you're talking to, a self-sustaining subsonic flame front and a sharp pressure spike are a perfectly valid explosion.
▲stouset 14 minutes ago
You don’t want detonation, but you do want deflagration.
▲felooboolooomba 2 hours ago
Pro tip: Show a message if WebGL is disabled instead of a blank space.
▲fauria 1 hour ago
"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.
▲arlattimore 36 minutes ago
The bearing surfaces in an engine (ex: crankshaft main bearings) have very tight tolerances, usually in the 15-25 thousandths of an inch. The engines oil pump fills those tiny gaps with pressurized oil which allow the metal surfaces to spin thousands of times per minute without damage.

This is also why if you have any issue with oil pressure (ex: oil pump failure, cracked oil line) or oil starvation (ex: driving a regular car on a race track, cornering forces slosh oil away from the oil pickup in the sump) issues, you'll damage your engine nearly immediately.

▲WalterBright 22 minutes ago
That's the point of all uses of oil, other than rust prevention.
▲relaxing 13 minutes ago
Very interesting technology. Would be exciting to see a hardware startup build a product around this.
▲mberning 24 minutes ago
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.
▲bell-cot 4 hours ago
[2021] Originally 2333 points and 392 comments:

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

▲mrhottakes 1 hour ago
Excellent animations.
▲misiek08 1 hour ago
You meant - awful knocking combustion in the first, main animation? I never catches any real bug is those great posts, but this one, especially as first animation on the page - weird.
▲Toutouxc 31 minutes ago
You might be misreading the animation. It's a direct injection engine, the thing that happens during the compression stroke is fuel injection. Ignition happens a few degrees before TDC, which is realistic.
▲ 6 minutes ago
▲lostlogin 21 minutes ago
One of the rare situations where someone wants a bit of retard?
▲zuzululu 1 hour ago
[flagged]
▲throw567643u8 1 hour ago
Probably better for the environment too.
▲rootusrootus 1 hour ago
No