Ford GAA engine

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Ford GAA
Manufacturer Ford Motor Company
Production 1940 - 1950
Combustion chamber
Configuration 60° V8
Displacement 1,100 cu in (18.0 L)
Cylinder bore 5.4 in (137 mm)
Piston stroke 6.0 in (152 mm)
Valvetrain DOHC
Compression ratio 7.5:1
Fuel system Naturally aspirated (i.e., unsupercharged), Stromberg NA-Y5-G carburetors[1]
Fuel type Gasoline
Power output 450 hp (336 kW) @ 2600 rpm

The Ford GAA engine is an all-aluminum, 32 valve, DOHC, 60-degree V8 engine produced by the Ford Motor Company during World War II. It featured twin Stromberg NA-Y5-G carburetors,[2] dual magnetos and twin spark plugs making up a full dual ignition system,[2] and crossflow induction.[3]

The GAA was used to power several models and derivatives of the M4A3 Sherman tank. The engine displaces 1,100 cu in (18 l) and puts out over 1000 ft lbs of torque from idle to 2600 rpm. Maximum rated horsepower was 525@2800 rpm though most models were rated at 450HP.


Immediately preceding World War II, Ford developed an aircraft engine similar to that of the Rolls-Royce Merlin and Allison engines of that era. It was a 60 degree V-12 with aluminum block and head, dual overhead camshaft, and 4 valves per cylinder. The intention of this design was to help Ford break into the anticipated large market for fighter engines. This engine was built to typical aircraft standards: it was light, high performance, and highly reliable.[citation needed] Everything was safety wired or staked with close attention to detail on every part. Available information suggests this design performed well[citation needed].

However, this engine never went into production as an aircraft engine due to the US Navy's decision to only use radial engines for its aircraft, and the Army's contractual commitments to existing engine manufacturers.

With the approach of war, increasing orders for the M4 tanks were causing supply issues with the existing engine. The U.S. Army decided they needed to source an engine supplier, so Ford removed 4 cylinders from the design and it went into production as a V-8.


Ford GAF V8 tank engine, next to an M26 Pershing, Bovington Tank Museum
  • The GAA was used in the M4A3 (1,690), M4A3(75)W (3,071), M4A3(76)W (1,400), M4A3 (105) (500), M4A3E2 (254), M4A3(76)W HVSS (3,142), M4A3(105) HVSS (2,539), M10A1 (1,413), and M7B1 (826).
  • The Ford GAF powered the M26 (2,222), M26A1, T95, and M45 (185).
  • The Ford GAN, powered the T23 (248) and M4A3E2 (254).
  • In order to meet the need for a larger engine, Ford resurrected the V-12 as the GAC, which produced 770 hp and powered the T29 (6).
  • A number of M74 tank recovery vehicles were rebuilt from M4A3s, which used the GAA.[4]

See also[edit]


  1. ^ Berndt, Thomas. Standard Catalog of U.S. Military Vehicles (Krause Publications, 1993), p.193.
  2. ^ a b Berndt, p.190.
  3. ^ Berndt, pp.190 & 193.
  4. ^ Berndt, p.193.


External links[edit]