Napier Sabre combat ratings, probably 1945.

[NeilStirling]

Napier Sabre combat ratings prior to the MK VII.

Neil.

 

[Simon Thomas]

Thanks for posting that.

Interesting that the performance lines are straight, even with the abscissa being linear with altitude.
Typically engine performance charts are drawn with the abscissa being linear with the altitude air density/sea level air density ratio. This means the altitude labels are on a non-linear scale. This is done as it makes the performance "curves" generally linear. This was based on the paper "Altitude Performance of Aircraft Engines Equipped with Gear-Driven Superchargers" R. F. Gagg, E. V. Farrar https://www.jstor.org/stable/44437712

I'll leave it to others to discuss the boost ratings...