When you're mapping the YB cosworth engine (or any engine really when I think of it, but let's say the YB to simplify a bit).
What is the mechanical factors that limits power output ?
Let's use a stage 3 escort Cossie as a first example and another one with anything you like on it to make as much power as possible (still 2 litres).
I really like this post.
Airflow is the one thing that determines engine power