Re: [MBZ] Partly OT - cold air into exhaust

[Peter Frederick]

You run into trouble if there are large leaks in the exhaust very close 
to the valves, not from air getting in but from excessive heat from 
lack of back pressure --remember, the valve train is designed to have 
the pressure from forcing the exhaust out the pipes, and if you don't 
have pipes you have to change the valve timing to prevent live flame 
from surrounding the exhaust valves under heavy load.  This burns them, 
not air entering the pipes.

Can do goofy things to performance, too, from screwed up airflow, but 
not that far back.

Peter