You might like to do some research - before you spend any money - on what hardware you actually need. This depends, obviously, on what software you are going to be using, but it does seem to me that if you really are intending to operate at the Cray level, you don't need any help from anybody here. A lot of perfectly capable CFD software that can give you a start, at least, with any but the most complicated problems will run well on up-to-date PCs - you don't even need a workstation.
KIVA is free... but your time is not. What do you want to model? IC engine simulation is a broad subject. KIVA can only really do a small portion of what constitutes a cycle.
