you mention POWER, rate of doing work...
you don't mention revs ?
thus a larger cap engine will make more power lower revmlikem for like, thus choke itself higher up ? No ?
I agree, BHP is a measurement of power which is the rate of doing work. So, I don't need to mention revs as we are talking about a BHP limitation, not a revs limitation of the exhaust components including the turbine and housing. Though it is obvious that ALL OTHER THINGS BEING EQUAL a 2.5 litre engine will make the same power as a 2 litre engine, at lower revs. Having said that, the amount of fuel consumed per unit of power, and therefore the amount of air consumed, and as a consequence the mass of exhaust products per unit of power, will be the same for a 2 litre engine and a 2.5 litre engine producing the same power.
If this wasn't so, a 2.5 litre engine would consume more fuel per BHP than a 2 litre engine per BHP, so the BSFC would be 125% higher in the larger engine. This plainly isn't the case.