In Turbo applications, there is a very simple equation to calculate power gain compared to atmospheric engines. This equation includes the following 5 factors:
Power = Po x PR x DC x PL
Here:
Po is the original power rating of the engine: let's say 240 hp
Pressure + 14.7
PR is the pressure ratio. For example - by calculating --------------------- this ratio becomes 1.49 at 7 psi pressure.
14.7
DC is the correction of the change in density depending on the temperature of the intake air. At 7 psi, this correction can be accepted as .85 when the intercooler is not used and .96 when the intercooler is used.
PL is the ratio related to the power of the overfeed mechanism from the motor. In Supercharger systems, this loss is around 5% and in Turbo systems, the loss is around 1.5%. The reason for the low power loss in the turbo is that the turbo operates with hot exhaust gases from the engine. It should not be forgotten that 1/3 of the fuel burning in the engine turns into power, 1 in 3 is spent to warm up the internal equipment of the engine, 1 in 3 is thrown out of the exhaust. The turbocharger operates with much less loss than Supercharger systems because it uses this power thrown out of the exhaust.
If we look at the result by putting the numbers in place:
New Strength:
In the Supercarger system without intercooler:
P = 240 x 1.49 x .85 x (1-.05) = 289 hp
Turbo system using intercooler:
P = 240 x 1.49 x .96 x (1 - .015) = 338 hp
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