R-1830 vs. Allison V-1710

[Shortround6]

Ir was figured that the P-40 had 22% less drag than the P-36. That Explains the the higher speed with equivalent engines and the push for liquid cooled engines, but since technology doesn't stand still later air-cooled engine installations cut into that margin quite a bit. The people in charge of ordering planes could only go with what was known at the time, not what would become known in 2-3 years.

 

[Jay Flynn]

Ir was figured that the P-40 had 22% less drag than the P-36. That Explains the the higher speed with equivalent engines and the push for liquid cooled engines, but since technology doesn't stand still later air-cooled engine installations cut into that margin quite a bit. The people in charge of ordering planes could only go with what was known at the time, not what would become known in 2-3 years.

Sorry I m so late on this, but PW DID built a Hawk 81 powered by a two stage two speed Twin Wasp and got 389mph out of her at 22K ft, albeit without armament.

 

[Shortround6]

That Explains the the higher speed with equivalent engines and the push for liquid cooled engines, but since technology doesn't stand still later air-cooled engine installations cut into that margin quite a bit. The people in charge of ordering planes could only go with what was known at the time, not what would become known in 2-3 years.

Sorry I m so late on this, but PW DID built a Hawk 81 powered by a two stage two speed Twin Wasp and got 389mph out of her at 22K ft, albeit without armament.

You are correct, they did, in 1943. Which is a little late for being the engine of choice for the P-40 in 1939 or 1941.
We have pictures of it a number of threads on this site. A better cowl than the P-36, the two stage supercharger allowing max speed at 22,000ft instead of 10-12,000ft and much better use of exhaust thrust compared to the P-36/Hawk 75.

 

[MIflyer]

Note that after WW2 Canadair built a conversion of the DC-4 called the North Star which replaced the R-2000 engines, a version of the R-1830, with the significantly more powerful Merlin 620 engines. This was not a very popular modification and despite the availability of large numbers of surplus V-1710's no one else tried replacing the R-2000 with in line engines. The R-1830 and V-1710 were two different engines good for two different kinds of aircraft.

As for the R-2800 it benefited enormously from the long period of earlier service of the R-1830 Wasp, and with refinements to the valves and cylinders really was a Double Wasp. In the 1980's a company addressed the shortage of parts for rebuild of the R-1340 by modifying R-2800 cylinders to fit on an R-1830 case.