JtD,
It is a basic principle of heat exchanger efficiency. It is not really open to much discussion and the fact so much is made of such a simple thing is telling.
Bongodriver, by all means post your findings. You might learn something.
Take a guess what the p is in the formula??
Don't let that stop you from posting the findings from a turbojet. We can then change the subject to some basic properties of thrust producers! Like I said, you will learn something!