I used to have one of those plastic see-through models of an engine, and it sucked. Finally someone has gotten a damn camera in a real engine so I can really see what's going on in there. The camera was high-pressure and heat-resistant, shooting at 1,000 fps, so you get some sweet slow-mo action. It was pretty much what I imagined, including how it turned me on. Now if you'll excuse me, I'm going to throw open the hood on the ol' Plymouth and hump something in there.
Micro Camera Shows The Workings Of A Combustion Engine [gizmodo, thanks to Rasttapas for the tip]