Suck Squeeze Bang Blow

No, not a disastrous night with a fatally flawed inflatable friend, but the wonders of the four-stroke (and two-stroke) engine revealed by animated gifs. Look at that expansion pipe working its pressure-wave magic. I find these hypnotic. Click for slightly bigger versions (especially the stroker, else you can't see the whole pipe) then sit back and stare till you drool. MP