Engine
Turbo Boost
Pressure ratio, charge temperature and estimated power under boost.
Inputsdrag · tap · type
kW
bar
%
%
°C
m
Fig. 06Charge-air path and power vs boost
With intercoolerNo intercoolerIdeal (isothermal)
Estimated power252kW+68 % over naturally aspirated
Pressure ratio1.79
Density ratio1.68
Compressor outlet102°C
Intake charge temp44°C
Manifold pressure (abs)1.81bar
§ How it works
A turbocharger makes power by packing more air mass into each cylinder. What matters is not boost pressure itself but how much denser the charge is when it reaches the intake valve. Compressing air heats it, and hot air is thin, so some of the pressure gain is lost again as temperature.
1 · Pressure ratio
Boost gauges read pressure above atmospheric, so the compressor sees absolute pressure. At altitude falls and the same gauge boost needs a higher ratio.
2 · Compressor outlet temperature
Temperatures are in kelvin. is the compressor's isentropic efficiency, read from its map; 65 to 78 % is typical.
3 · Intercooler
Effectiveness is the fraction of the temperature rise the intercooler removes. A good air-to-air core manages 70 to 85 %.