Editing Allison V-1710 (section)

==Variants==

Allison's internal model designation for the V-1710 started with the letter A and proceeded to the letter H.  Each letter designated a family of engines that shared major components, but differed in specific design details.  Each of these designs were identified by a number, starting with number 1.  The last letter, which was introduced when both right hand turning and left hand turning engines were built, identified by the letter R or L respectively.

The military model numbers were identified by a "dash number" following the engine description "V-1710". The USAAC/USAAF models were the odd numbers, starting with "-1" and the USN models were the even numbers, starting with "-2".<ref>Whitney 1998, p 104, 399</ref>

;{{vanchor |V-1710-A}}:
"A" series engines were early development engines for the USN and USAAC.  The first military model was a single V-1710-2, which was first sold to the USN on June 26, 1930. The "A" engines had no counterweights on the crankshaft, 5.75:1&nbsp;compression ratio, 2:1&nbsp;internal spur gear-type reduction gear boxes, 8.77:1&nbsp;supercharger ratio, {{convert|9.5|in|abbr=on}} impeller, SAE #50 propeller shaft, a float-type carburetor, and produced {{convert|1070|hp|abbr=on}} at 2800&nbsp;rpm on 92 octane gasoline.<ref>Whitney 1998, Chapter 7</ref>

;{{vanchor |V-1710-B}}:
"B" series engines were designed for USN airships. The military model was V-1710-4. They differed from the "A" series engines in that they did not have a supercharger, had two float-type down-draft carburetors were mounted directly to the intake manifold, an SAE #40 propeller shaft, and could be brought from full power to stop and back to full power in the opposite rotation in less than 8 seconds.  They produced {{convert|600|-|690|hp|abbr=on}} at 2400&nbsp;rpm.<ref>Whitney 1998, Chapter 8</ref>

;{{vanchor |V-1710-C}}:
"C" series engines were developed for highly streamlined pursuit aircraft for the USAAC, and are easily identified by the long reduction gear case.  The military models were V-1710-3, -5, -7, -11. -13, -15, -19, -21, -23, -33, producing between {{convert|750|-|1050|hp|abbr=on}} at 2600&nbsp;rpm. These engines came in two groups, one group rated at full power at sea level, the other rated at full power at high altitude.  The altitude rating difference was in the supercharger gear ratio, four of which were used: 6.23:1, 6.75:1, 8.0:1  and 8.77:1.  These engines received heavier crankcases, a stronger crankshaft,  SAE #50 propeller shaft, and Bendix pressure carburetors.<ref>Whitney 1998, Chapter 9</ref>

;{{vanchor |V-1710-D}}:
"D" series engines were designed for pusher applications using propeller-speed extension shafts and remote thrust bearings mounted to the airframe. The military models were V-1710-9, -13, -23,  and  -41, producing {{convert|1000|-|1250|hp|abbr=on}} at 2600&nbsp;rpm. Supercharger ratios were 6.23:1, 8.0:1 or 8.77:1, depending on altitude rating. These engines had the compression ratio increased to 6.65:1. Marvel MC-12 fuel injection, which was unsatisfactory and quickly replaced by a float-type carburetor on -9 and -13 models.  Later dash number engines used Bendix pressure carburetors.  These engines were being designed at the same time as the V-3420 engine, and shared many assemblies as they were developed.  The "D" series engines were the last of the "early" V-1710 engines.<ref>Whitney 1998, Chapter 10</ref>

;{{vanchor |V-1710-E}}:
"E" series engines were designed for remote gearbox applications using crankshaft-speed extension shafts and remote 1.8:1 gearboxes with SAE #60 hollow propeller shafts. The military models were V-1710-6, -17, -31, 35, -37, -47, -59, -63, -83, -85, -93, -103, -109, -117, -125, -127, -129, -133,-135 and -137, producing {{convert|1100|-|2830|hp|abbr=on}} at 3000&nbsp;rpm. Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.6:1 depending on altitude rating.  These engines were a complete redesign, and did not share many components with the earlier engine series. Almost all components were interchangeable with later series engines and the V-3420, and could be assembled as right hand or left hand turning engines in either pusher or tractor applications.<ref>Whitney 1998, Chapter 11</ref>

;{{vanchor |V-1710-F}}:
[[File:Lockheed P-38G-1-LO Lightning LOC fsa.8d22579.jpg|thumb|[[Lockheed P-38 Lightning|P-38G]] engine, in this case V-1710-51/55 (F10) which this series used]]
"F" series engines were designed for late model pursuit aircraft, and are identified by the compact external spur gear-type reduction gear box. Military models were V-1710-27, -29, -39, -45, -49, -51, -53, -55, -57, -61, -75, -77, -81, -87, -89, -91, -95, -99, -101, -105, -107, -111, -113, -115, -119, producing {{convert|1150|-|1425|hp|abbr=on}} at 3000&nbsp;rpm. The V-1710-101, -119 and -121 models has an auxiliary supercharger, some with a liquid-cooled aftercooler. Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.60:1 depending on altitude rating. These engines had either a six or twelve weight crankshaft, revised vibration dampeners that combined to allow higher engine speeds,  SAE #50 propeller shaft, and higher horsepower ratings.  The "E" series and "F" series engines were very similar, the primary difference being the front crankcase cover, which was interchangeable between the two series engines.<ref>Whitney 1998, Chapter 12</ref>

;{{vanchor |V-1710-G}}:
"G" series engines were designed for high-altitude pursuit aircraft, and are identified by the auxiliary supercharger with a Bendix "Speed-Density" fuel control. Military models were V-1710-97, -131, -143, -145, and -147, producing {{convert|1425|-|2300|hp|abbr=on}} at 3000&nbsp;rpm. Supercharger gear ratios were: 7.48:1, 7.76:1,  8.10:1, 8.80:1 and 9.60:1 depending on altitude rating. These engines were equipped with an SAE #50 propeller shaft and a single power lever to regulate engine performance, reducing the pilot's workload when managing this very complex engine.<ref name="Whitney">Whitney 1998, Chapter 13</ref>

;{{vanchor |V-1710-H}}:
"H" series engines were to use a two-stage supercharger driven by a two-stage air-cooled power recovery turbine. The engine was to have an aftercooler and port-type fuel injection.  This variant, however, was never built.<ref name="Whitney">Whitney 1998, Chapter 13</ref>

{| class="wikitable" style="width:80%; margin:0.5em auto" cellpadding="0"
|+{{vanchor |Selected Allison Engine Models}}<ref>Whitney 1998, pp 30, 31, 37–49</ref>
! AEC Model
! Military Model
! Arrangement
! style="width:40%;"|Notes
|-
| A1
| GV-1710-A
| 
| 1 built. Rebuilt 2 times as XV-1710-2.
|-
| A2
| XV-1710-1
| Long reduction gear housing
| Testing. 1 built.
|-
| B1R, B2R
| XV-1710-4
| Quick reversing, remote 90 degree gearbox
| 3 built for airships
|-
| C1, C2, C3, C4, C7, C10, C15
| XV-1710-3, -5, -7, -9, -21, -33
| Type test engines
| 16 built. C2 rebuilt from -5 to -7. C4 first flight engine in A-11A and later in XP-37
|-
| C8, C9
| V-1710-11, -15
| Long nose
| 3 built. C8 RH turn for XP-37, XP-38, C9 LH turn for XP-38
|-
| C13
| V-1710-19
| Long nose
| Early production P-40 engine
|-
| D1, D2
| YV-1710-7, -9, XV-1710-13
| Pusher with extension shaft
| 6 built for XFM-1
|-
| E1, E2, E5
| V-1710-6, -17, -37
| Remote gearbox
| 5 built for XFL and XP-39
|-
| E4, E6
| V-1710-35, -63
| Remote gearbox 
| P-39C engine
|-
| E11, E21, E22, E27, E30, E31
| V-1710-47, -93, -109, -117, -133, -135
| Remote gearbox 
| P-63/A/C/D/E/F/G/H engine
|-
| E23RB, E23LRB
| V-1710-129
| Remote gearbox 
| Douglas XB-42 dual installation with combining gearbox and extension shafts
|-
| F1
| V-1710-25
| Short nose
| 1 built Development engine for XP-38
|-
| F2R, F2L
| V-1710-27, -29
| Short nose
| P-38D/E engines
|-
| F3R
| V-1710-37
| Short nose
| 2 built for NA-73X Mustang prototype
|-
| F3R
| V-1710-39
| Short nose
| P-40D/E and P-51A Production engine
|-
| F4R
| V-1710-73
| Short nose
| P-40K engine
|-
| F5R, F5L
| V-1710-49, -53
| Short nose
| P-38F engine
|-
| F10R, F10L
| V-1710-51, -55
| Short nose
| P-38G engine
|-
| F15R, F15L
| V-1710-75, -77
| Short nose
| XP-38K engine, 1,875&nbsp;hp (WEP), geared 2.36 to 1 for use with [[Hamilton Standard]] Hydromatic "high activity" propellers
|-
| F30R, F30L
| V-1710-111, -113
| Short nose
| P-38L engine
|-
| F32R
| V-1710-119
| Short nose and two-stage supercharger
|  XP-51J
|-
| G1R
| V-1710-97
| &nbsp;
| WER test engine
|-
| G3R
| V-1710-131
| &nbsp;
| geared drive
|-
| G4R
| 
| &nbsp;
| remote extension shaft drive version of G3R
|-
| G6R, G6L
| V-1710-145 -147
| &nbsp;
| P-82E/F engine
|-
|}