I think I might be confused but can't get my mind around where. I don't see how more compression spools a turbo at a lower engine speed. I think higher compression makes the engine rev faster which results in the engine getting to the threshold were it can spool the turbo faster. This means the turbo is spooling faster but not at a lower engine speed. The engine simply got to the speed at which it spools the turbo faster. Here is why I think this. What spools a turbo is flow through the turbine. Anything that makes the engine breath better at a given engine speed makes the turbo spool faster at that speed. Compression does not increase flow like other mods do. It makes the engine more efficient meaning it makes more power with the same flow through it.



In summary I think that more compression makes a turbo spool faster but not at a lower engine speed.

 

Not exactly. Heat. Heat energy is what spins the turbine. Higher compression engines burn hotter making them more efficient (hotter in the cylinder means more fuel burns in the cylinder before the exhaust valve opens). More heat spools the turbine faster by increasing exhaust velocity. This is why people wrap or coat their manifolds and turbine housings... to keep more heat in. It's all about the thermodynamics.

 

Hotter air takes up more space, so moving the same mass of hotter air moves a larger volume of air.