Here are some useful engine examples from howstuffworks.com. They have a number of linked pages devoted to engines. You can start here.  Here are some examples of what you will see …

Here is a classic engine (how stuff works page link):

Here is an overhead cam example (how stuff works page link):

This is an inline 4 example (how stuff works page link):

This is a V example (how stuff works page link):

And here is an electrical system example (how stuff works page link):