what engine do i have?
This is probably the most difficult question any prospective or current Mini owner may ask. Because many Minis no longer have the original engine and because it's difficult to tell from the outside. Either you have to take the previous owner's word for it, or rip apart the engine and do some measuring. Although I'm not aware of a completely foolproof meathod, here is a quick tip that I found useful.
998cc
The 998cc engines had a radiator host that exited the block at a 45 degree angle.
1275cc
The 1275cc engines had a radiator hose that exited the block parallel to the radiator.
As I said earlier, this is not a fool proof meathod, but it is a good guide. Here is a useful link that can help you determine your original engine size if you have the engine number.
http://www.guess-works.com/Tech/engine.htm
http://www.guess-works.com/Tech/engine.htm