Back Pressure

[Wizard]

The big thing with backpressure on a NA car is exhaust flow out of the combustion chamber once the valve is opened, and when the 2 cams overlap (both valves slightly open to purge the chamber of burnt gasses). Too little backpressure on a NA car will also burn valves. This is mostly from sucking cold air back in thru the exhaust. Hot exhaust valves don't like cold air. A turbo car doesn't have to worry about that. Kind of impossible to get cold air back to the exhaust valves past a spinngin red hot turbine wheel.

Wiz