SameerP

That is to say, would (for example) a 9.5:1 compression engine spool up a turbo quicker than a 8.5:1 engine compression? Is there a formula to know these numbers?

Thx.

Cheers,
Sameer

Merkin

but high compression would be hotter so the volume would also be higher.

but the exhaust mass stays the same

birdsong

Displacement is not the only factor that influences exhaust volume. Basically, all products come out of the car as some kind of gas. CO2, CO, NO2, water vapor, etc. Conservation of mass says that whatever mass comes in, goes out. So anything that increases the incoming mass, increases the outgoing mass. In a forced induction engine, cranking up the boost increases the mass going in the engine. Thus, boost is a factor in total exhaust produced.

Merkin

volume = yes
mass = no

xr4tic

than a low-compression motor.

My best guess is because the higher compression motor will have higher cylinder pressures, causing the motor to accelerate faster, thus faster response off-boost, and quicker spooling.

On the flip-side, a low compression motor will handle more boost.

It can handle more boost because the cylinder pressure is lower.

If the cylinder pressure gets too high, then detonation occurs, as the heat created from the compression can ignite the fuel if it gets too hot.

xr4tic

so if the RPM accelerates faster, there is more exhaust volume produced over a given period of time.