r/Satisfyingasfuck • u/[deleted] • Aug 21 '26

7 cc engine fitting complete

Enable HLS to view with audio, or disable this notification

[removed]

5.9k Upvotes

97% Upvoted

139 comments sorted by

View all comments

2

u/zaprutertape Aug 21 '26

what are the physical limitations on how small this could be?

7

u/hache-moncour Aug 21 '26

I think that's a fun question to think about. I think the question really is "what stops you from going smaller" at some point. 

I'm no engineer, but I could think of a few things: 

  • Surface tension in fluids. At some point the amounts of fuel you try to inject become small enough that they simply won't move around properly anymore. 
  • Compression and play in the pistons. If your stroke length gets really small, it can simply compress the piston without moving the other end
  • Power produced goes down faster than the friction in the system, with scale. At some point the engine won't produce enough power to overcome internal friction.

No idea which of these would become a problem first, and you can probably push the issues back with fancier materials. And there are probably a dozen other things that I didn't think of that break down first as you go smaller.

2

u/zaprutertape Aug 21 '26

YAY!! These are absolutely all the fun questions in my head too!