[.041 Safety Wire]

I understand about the single stage S/C, but the reference you're quoting on Hydro Boats is talking about a 2nd stage. These engines appear to be modified by that group. ie. Brought up to current day expectations.

They were not modified by the hydro guys but by Allison as this is a G series. F series were used in P40 and P38 and the E,s were for the 39 and 63,s .
The last iterations of the V-1710 powerplants were two speed, two stage supercharged where as the orginals that powered the P-40 were single stage single speed which is the point Im trying to make. The P-40 powerplant is supercharged but it is not turbo charged.

The power unit on the "E" and "F" engines were identical, with crankshafts, connecting rods, pistons, cylinder blocks, valve gear, and intake manifolds among other components completely interchangeable. The "E" featured a remote propeller reduction gearbox for the Bell P-39 Airacobra (and P-63 Kingcobra) driven with a 10 ft extension shaft turning at crankshaft speed between the engine and reduction gear. The "F" had a conventional integral tractor propeller reduction gear Lockheed P-38 Lightning and Curtiss P-40 Tomahawk. A turbocharged V-1710-F17L/-F17R engine equipped with ADI produced a WER of 2,300 bhp at 3,000 rpm with 90 in hg,, developing a BMEP of 355 psi. The "E" and "F" engines were the bread&butter Allisons, with these engines used in large volume on several major fighter programs of WWII. A total of 66,658 "E" and "F" types were built -- 18,998 "E"-type extension shaft engines were shipped, mainly for P-39 and P-63 aircraft, and 47,660 "F" models were shipped, mainly for P-38 and P-40 airplanes.



The ultimate V-1710 was the "G" series which brought together all of Allisons design and manufacturing experience to produce an outstanding engine in almost all respects from earlier engines. The V-1710-G was incorporated a number of desired improvements identified in 1943 by Wright Field (U.S.A.A.F. engineering/procurement organization) and improve performance to 1,725 bhp at 3,400 rpm. To improve performance, the 12-counterweight crankshaft developed in late 1942 was used to increase the maximum rpm to 3,400, the induction path was improved to increase flow, and improvement were also made to the supercharger, cylinder heads, and accessories section. One interesting characteristic of the "G"-series was the large proliferation of features and configurations -- short-nose integral reduction gears or extension shafts, with and without auxiliary superchargers, both 9.5" and 10.25" engine supercharger impellers, one or two-speed supercharger drives, a range of supercharger drive ratio's, three compression ratio's, pressure (injection) carburetor, speed density injection, or port fuel injection, and both left and right hand rotation. These engines became the most desirable to racers because of the high-revving crankshafts and improved detail design. A total of 763 were produced -- a batch of 750 V-1710-G6R/-G6L consisted of virtually all the "G" series production. When this batch of engines were declared surplus in the 1950's, they were said to to have been the engines which powered Unlimited Hydroplanes into the 1990's (Daniel D. Whitney, "Vee for Victory", pg 278). This same source describes how the Unlimited Racers traded performance for engine life, modifying engines to deliver as much as 4,000 hp.