Someone suggested to me t04b w/ a 1.15A/R and I know another person who runs a t04e w/ 1.15AR and I'm used to seeing people just stick w/ .8 and 1.0 and just go w/ bigger compressors.

What is the difference in a small compressor and huge a/r and a medium compressor and medium a/r that produce similar power?

Thanks,
Ben Martin

 

Compressors should be sized for the air consumption of the engine and the boost pressure desired. This is what a compressor map is for. Pick one that indicates high effeciencies in the flowrates and pressure ratios that you want the best performance in.

Turbines must also be sized for air consumption of the engine. Another aspect that must be taken into account is the temperature of the exhaust. This is why rotaries, when compared to piston engines, run larger A/R turbines. Rotaries have hotter exhaust gas, this expands the air to fill a larger volume and therefore needs more flow area to process the same amount of mass.

Increasing the A/R of your turbine will increase the flow area, and reduce the velocity. This is why large A/R tubines have good top end power and sacrifice spool.

Justin

 

OK, think I gotcha.