This site has some great write-ups on the mechanics of an engine. A lot of it is a review.. (even for a n00b like myself), but I think it's recommended reading for anyone who wants to know more about the basic workings of an internal combustion engine!
Basic introduction is divided into FOUR MAIN SECTIONS of interest:
Introduction to How Car Engines Work--
A very basic intro. It may even seem patronizing to some of the people who find themselves in this section of Club3g... 
Cylinders, Displacement and Other Engine Parts--
starts with the three basic cylinder arrangements in automotive engines, covers displacement, then goes into other parts that translates the engine's energy. wraps with "what can go wrong" 
Valve Trains and Systems--
starts to get interesting here as well as more relevant to my project. also includes a link to another author's article on "How Camshafts Work"...hmmm 
Producing More Power--
YESSss! ... haven't read into it yet, but seems to be a link-heavy discussion on upgrading an engine. (the basics)
followed by a FIFTH PAGE:
Lots More Information--
their standard list of related HSW articles...
This whole site is a great reference tool. I recommend even visiting the "
Science Stuff" section for some of the technicalities! .....
(I'm such a geek)