Quote:
Originally Posted by kevin1985912
where is the boost pressure measured? how can gt60 flow more air at the same boost pressure? Pv=nRT, gas constant R, temperature T and volume of the engine V stay the same, so P = n, n is the number of mols of gas molecules, more air flow means higher mols of gas molecules so n goes up. If all the other variables stay the same, increasing the number of mols of gas molecules means increasing pressure. Right?
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You are missing time in your equation.
Pressure * Volume/time = #moles/time * Gas Constant * Temperature
GT25 = 22lbs/min@8psi at the choke line on the compressor map
GT60 = 125lbs/min@8psi at the choke line on the compressor map
Remember that horsepower is work over time. The more airflow you have (cfm, lbs/min, etc.), the more power you make provided you have enough fuel.
Boost pressure is the measure of restriction to airflow, which is why it is practically meaningless when trying to determine horsepower. Lbs/min and cfm are what matters...again, because you are relating a time based unit to a time based unit (airflow to horsepower).
Back on topic, Phunk nailed it.