Engine on P-39M

[Vincenzo]

Commonly i read that the P-39M had the V-1710-67, but for this https://www.enginehistory.org/Piston/Allison/AllisonSpecs/AllisonSpecs.shtml the -67 not going in mass production, there is a wrong in the table? or is not the -67 actually installed on P-39M?

 

[Shortround6]

According to "Vees for Victory" page 150, some were powered by V-1710-63(E6) but most were powered by the V-1719-83 (E18) The V-1710-63 used 8.80 supercharger gears.
A chart on page 430 shows two V-1710-67 (E8)s as being built, or same engine rebuilt. One had a 2:1 reduction gear and the other a 2.27:1 reduction gear.

946 of the V-1710-63 engines built
1,034 of the V-1710-83 engines built.

 

[Vincenzo]

Thanks Shortround6
so this do come an other demand, what is the difference from the early M, that with -63, and the L?

 

[jmcalli2]

Commonly i read that the P-39M had the V-1710-67, but for this https://www.enginehistory.org/Piston/Allison/AllisonSpecs/AllisonSpecs.shtml the -67 not going in mass production, there is a wrong in the table? or is not the -67 actually installed on P-39M?

I found this on http://www.enginehistory.org/References/ModDesig/I31.jpg. Looks like the P-39M used the-83 and -85 models of the V-1710.

 

[larrymc]

White's Allied Aircraft Piston Engines of World War II (SAE Press) lists V1710-83 as used on Bell P-39L/M/N/Q and -85 used on P-39M/N/Q (page 383)
The -83 is described as "similar to -63 except supercharger gear ratio and equipped with automatic boost control."
The -85 is described as "similar to -83 except propeller reduction gear ratio and equipped with automatic boost control."
The -67 is described as "similar to -63 except larger oil pumps and slight difference in accessory drive."

 

[Vincenzo]

Thanks to both jimcalli2 and larrymc

 

[P-39 Expert]

Thanks Shortround6
so this do come an other demand, what is the difference from the early M, that with -63, and the L?

Hardly any difference in the K/L/M if the M has the earlier -63 engine. Same Bell Model 26, same engine, just different propellers. K used the newer hydromatic propeller first used on the F model. Then the L reverted to the Curtiss electric prop, and the M-Q switched back to the hydromatic prop. I have seen references to the M having the Curtiss electric prop also. Props got a little larger with the N-Q.

Then again, not much difference in any of the P-39 models except for the propellers, reduction gears, (different versions of the same) engines, radios and armament. Way too much alphabet for the minor changes, would have simplified things with more dash numbers.