V-1710-115 (F31R) Manuals?

[Think Tanker]

Heya gents!

So, recently I have been doing some digging into the V-1710-115 (aka the F31R V-1710) engine with particular interests pertaining to its power and efficiency at certain altitudes. I know of numerous websites which cite 1,350 HP output for the engine, but I would be curious to see if there are any actual mentions of the power performance of the engine under Military Rated Power, War Emergency Power, Cruising, Take-Off, etc. Specifications, sources, or preferably manuals on the performance of this engine.

Any help you all can offer would be greatly appreciated!

 

[tomo pauk]

Looks like the engine was making 1125 HP at 15000 ft:

'Vee's for victory' book says the performance was same as it was with the F-26R (V-1710-99), that have had following specs (including the 1480 HP WER at 7500 ft; all altitudes I've posted are without ram effect):

 

[Think Tanker]

Yeah, I do indeed have those statistics for the V-1710-99 engine, but I am still skeptical that there was no change in the performance of the engine similar to how a stronger assembly allowed for the V-1710-39 to put out more power than the V-1710-33 (IIRC). Are there any actual manuals and or charts representing this engine specifically?

 

[tomo pauk]

The changes in the F31R vs. F26R were of far smaller scope than what was the case with -39 vs. -33.

 

[Think Tanker]

I hear you on that, but I am wondering where the 1,360 HP figure is coming from...from my personal searches I cannot find anything of reasonable value citing performance of the engine minus what you have shown above.

 

[tomo pauk]

Where have you read the 1350-1360 HP figure for the F31R?

 

[Think Tanker]

Variants P-40N

Here, primarily.

 

[tomo pauk]

The original of that article is here: link.

I've checked out two sources listed, the 'Curtiss aircraft' by Bowers, and Ray Wagner's on-line version of his book on American aircraft. Neither mentions the 1350-1360 HP figure, that, now thinking about that, is not mentioned with regard to the altitude it is supposed to attain.
I'm not sure that 1480 HP on WER is that shabby either

 

[Think Tanker]

The original of that article is here: link.

I've checked out two sources listed, the 'Curtiss aircraft' by Bowers, and Ray Wagner's on-line version of his book on American aircraft. Neither mentions the 1350-1360 HP figure, that, now thinking about that, is not mentioned with regard to the altitude it is supposed to attain.
I'm not sure that 1480 HP on WER is that shabby either

Indeed, although of course, it is almost the same power which the P-40E-1 (1,470 HP) and all P-40N (1,480 HP) variants had
Besides HP, since it would seem as if there was no noticeable change between the two, what other benefits would the stronger V-1710-115 provide in relation to the V-1710-99? It is about 30 lbs heavier than its predecessor, and otherwise may reduce the acceleration and climb of the P-40N aircraft.

 

[tomo pauk]

The engine extra weight is a weight of a single .50 HMG, ie. not that much. Extra engine weight is usualy a well spent investment.
Stronger engine, that is still at same dispacement, uses same S/C, same valvetrain, same compression ratio buys preciously few vs. the older engine that already has plenty of power. Now if the -115 was rated for 3200 rpm (not much of a stretch, but it was not to be), we'd see an usefull increase of power at higher altitudes. The low altitude power would've been limited by the air-fuel mixture temperature being too hot due to sharper pressure rise, thus leading to limiting either RPM back to 3000 there, or limiting the manifold pressure.

 

[MiTasol]

Yeah, I do indeed have those statistics for the V-1710-99 engine, but I am still sceptical that there was no change in the performance of the engine similar to how a stronger assembly allowed for the V-1710-39 to put out more power than the V-1710-33 (IIRC). Are there any actual manuals and or charts representing this engine specifically?

The -81, -99 and -115 are all very similar and the differences are all related to increasing reliability and reducing pilot and maintenance induced failures.
The -99 is essentially a -81 with an Automatic Engine Control added to reduce the problem of ham-fisted pilots over boosting (just as the earlier addition of Automatic Mixture Control was introduced to prevent detonation and other mixture related problems from ham-fisted pilots).
The -115 changes are about rectifying maintenance and other reliability issues.
For a period description of these changes see RAAF Allison Order 28 and 31 attached.