| Ford GAA | |
|---|---|
 | |
| Overview | |
| Manufacturer | Ford Motor Company |
| Production | 1940-1950 |
| Layout | |
| Configuration | 60°V8 |
| Displacement | 1,100 cu in (18 L) |
| Cylinder bore | 5.4 in (137 mm) |
| Piston stroke | 6.0 in (152 mm) |
| Valvetrain | DOHC |
| Compression ratio | 7.5:1 |
| Combustion | |
| Fuel system | Naturally aspirated engine withStromberg NA-Y5-Gcarburetors[1] |
| Fuel type | Gasoline |
| Cooling system | Liquid |
| Output | |
| Power output | 500 hp (373 kW) at 2,600 rpm |
| Torque output | 1,050 ft⋅lbf (1,424 N⋅m) at 2,200 rpm |
| Dimensions | |
| Length | 59.02 in (150 cm) |
| Width | 33.25 in (84 cm) |
| Height | 47.78 in (121 cm) |
| Dry weight | 1,470 lb (667 kg) |
TheFord GAA engine is an American all-aluminum 32-valveDOHC 60-degreegasoline-fueled liquid-cooled V8internal combustion engine with aflat-plane crank. It was designed and produced by theFord Motor Company during World War II. It features twinStromberg NA-Y5-Gcarburetors,[2] dualmagnetos and twinspark plugs making up a fulldual ignition system,[2] and crossflow induction.[3] Itdisplaces 1,100 cu in (18 L) and puts out well over 1,000 pound-feet (1,400 N⋅m) of torque from idle to 2,200 rpm. The factory-rated net output was 500 hp (370 kW) at 2,600 rpm.
The GAA powered several models and derivatives of theM4A3 Sherman medium tank.
After the start of World War II, theUK was looking to manufacture complicated parts — notably the crankshafts — of theRolls-Royce Merlin aircraft engine in the United States, but negotiations withPackard stalled because the company insisted on making complete engines. In June 1940 production drawings arrived in North America and were seized by theUnited States Department of the Treasury, providing an opportunity for Ford engineers to copy them and soon derive a version simplified for mass-production at Ford's factories. However, the prior text, provided without citation, is misleading and may be false. Ford was asked by the British Government to produce true Merlin engines, not a revised mass production version as the prior text claims, at their factories in England, and delivered 30,400 bomber engine variants of the Merlin by war's end. However, Henry Ford balked at producing the Merlin in Detroit and instead preferred to produce a fresh design, with the ambitious goal of 2000 hp. Although this design had the same bore and stroke as the Merlin, it shared no parts in common and differed substantially in several fundamental ways, such as having four overhead cams instead of the Merlin's two. This engine, called the XV-1650, was never produced, however, because the US Navy had no interest in water cooled engines in that power range and the US Army was obliged and loyal to Allison at the moment, and because of Henry Ford's tainted pre-war cooperation with Germany (Sources: Graham White, Allied Piston Aircraft Engines of World War II, 1995, and Herschel Smith, A History of Aircraft Piston Engines, 1981).
It was a 60 degree V-12 of 1,650 cubic inch displacement, with the cylinder bore and stroke matching the Merlin, using an aluminum block andhead;dual overhead camshafts, and four valves per cylinder. The intention of this design was to help Ford break into the anticipated large market for aircraft engines. This engine was built to typical aircraft standards: it was light, high performance, and highly reliable. Everything was safety-wired or staked, with close attention to detail on every part. Available information suggests this design performed well.[citation needed]
However, it never went into production as an aircraft engine due to the United States Navy's decision to only useradial engines for its aircraft and the Army's contractual commitments to existing manufacturers.[citation needed]
With the approach of war, increasing orders forM4 Sherman tanks were causing supply issues with the 9-cylinder radialWright R-975 Whirlwind engine used. The U.S. Army decided it needed to establish additional engine suppliers, choosing a version of the Ford GAA cut down from twelve cylinders to eight for various vehicle applications.
In 1942 after the British Tank Mission visit to America in April, there was some pressure from British car and commercial vehicle manufacturers to use the new Ford V8 tank engine designed by Larry Sheldrick in British tanks, rather than theMeteor then under development by Rolls-Royce from the Merlin aero engine, as they believed that an adapted aero engine "would not be suitable as a rugged tank engine". The Ford engine prototype had a few hundred hours test-bed running by that time. It was a liquid-cooled Vee similar to the Meteor, but two-thirds the size and Rolls-Royce executiveW. A. Robotham doubted its reliability at 600bhp. The 600 bhp Meteor was designed to fit in the same space in theCrusader tank as the NuffieldLiberty L-12 engine of 340 bhp output. The Ford V8 developed only 500 bhp, and had problems that were not overcome until after the Normandy landings in 1944.[4]
