Hi everyone,

Well I'm having my motor rebuilt as we speak, and I'm going to be switching from 8.5:1 to 9.0:1 rotors in my motor. My PFC is currently tuned for my old setup (8.5:1 rotors), and I was wondering if I'm going to need an immediate retune before I even think about driving it to break in the engine.

Of course I'm not going to be boosting until the motor is broken in and I can get a full retune, but I was wondering if it will be safe to drive around town to break in the motor before I get it retuned for the new turbo.

Thanks!

 

Time to think about basic automotive theory and operation.

What happens with a non turbo engine when compression is raised? The same volume of air and fuel is burned but at a higher pre-combustion pressure. This higher pressure is cause by the combustion chamber having less volume than befor. Most efficient timing will change and required octane rating will be raised , and power will increase.

With a turbo application you force air into the chamber. If you run the same boost level, less air will be forced into the chamber due to being smaller in volume. This requires less fuel. You end up with less air and fuel than before and when compressed, the pre-combustion pressure will be different than before.

 

Bump.

 

You just got your question answered