Read around any of these threads, and use the search tool. Theres alot of info already posted on motors. You just gotta pick one.
This thread has alot of talk about motors in it. Pretty good info, mostly Novarossi's. Which is a awesome motor company.
http://www.rctech.net/forum/nitro-of...ice-h-e-s.html
Plus 4 thread
http://www.rctech.net/forum/nitro-of...-plus-4-a.html
Just do some reading and searching. There are tons of threads just like this. Do some research here and at your local track. See if you will have local support for that motor.