Why did some planes have higher boost limits at altitude, and some had lower?

[Charon]

Naively, I would expect engines to be able to operate at the same boost pressures at both  high and low altitudes, provided the supercharger could deliver that pressure. But not all of them behave like that.

 

The Fw 190A-8 is limited to 1.58ATA in the first supercharger gear, but 1.65ATA in the second. Similarly, the Jumo equipped Fw 190D/Ta 152H generate higher boost pressures in the higher supercharger gears (as modeled in game, which I presume is correct).

 

The La-5F/FN (and I think the series 8 as well), on the other hand, is rated for higher boost pressures at lower altitudes (1140/950mm for the F, 1180/1000mm for the FN).

 

Why are the second-gear boost limits the same for some planes, higher for some, and lower for others? What was going on mechanically?

[cardboard_killer]

Some had the special "11" amps.

[JMax]

6 minutes ago, cardboard_killer said:

Some had the special "11" amps.

😊