Engines have always fascinated me. Can't explain why. I took my first car apart and (mostly) put it back together again. Here is a wonderful post/graphic on how engines work. The blog itself called ANIMIGRAFS by Jacob O'Neil is incredible has other wonderful stuff about jet engines and audio speakers. Here is one of the images from the car engine page:
He goes through Fuel, Oxygen, Cooling, Exhaust. I love this stuff.