Willys Go Devil engine

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For a logging sled, see Go-devil.
Go Devil
Willys MB (Bild 6 2008-06-14) Motor.JPG
Manufacturer Willys-Overland
Combustion chamber
Displacement 134.2 cu in (2,199 cc; 2.199 L)
Cylinder bore 3.125 in (79.4 mm)
Piston stroke 4.375 in (111.1 mm)
Cylinder block alloy Iron
Cylinder head alloy Iron
Valvetrain L-head
Compression ratio 6.48:1
Fuel system 1-barrel carburetor
Fuel type Gasoline
Cooling system Water-cooled
Power output 60 hp (45 kW; 61 PS)
Specific power 0.42 hp/CID
Torque output 105 lb·ft (142 N·m)
Successor Willys Hurricane engine

The Willys L134 (nicknamed Go Devil) is a straight-4 automobile engine that was made famous in the Willys MB Jeep produced during World War II. It powered nearly all the Jeep vehicles built for the U.S. and Allies.[1] It was later used in a variety of civilian Jeep vehicles.


In 1940, the Willys Quad was built to compete against the Bantam reconnaissance car for evaluation by the U.S. Army.[2] The two prototype Quads were powered by the Willys “Go-Devil” engine that turned out to be automaker's greatest asset.[2] Willys pilot vehicle was overweight compared to the Army's requirements, but the "Go Devil" engine rated at 55 hp (41 kW; 56 PS) included a heavier transmission, a combination that proved to be beneficial in the long-run for use in cross-country travel.[3]

The engine was developed by Willys' Chief Engineer, Delmar "Barney" Roos, and was the most powerful of the three prototype vehicles evaluated by the U.S. Army for production.[4] Roos took the "less than impressive" 48 hp (36 kW; 49 PS) automobile engine and increased its performance and durability.[5] The specifications by the Quartermaster Corps called for only 85 lb·ft (115 N·m) of torque at the rear axle.[5] The extra power made it the engine of choice for the U.S. Army.[5]

The engine displacement was 134.2 cu in (2,199 cc) with a 3.125 in (79.4 mm) bore and 4.375 in (111.1 mm) stroke, a very undersquare design. It was an L-head design, with valves parallel to the cylinders. Initial power output was 60 hp (45 kW; 61 PS) at 4000 rpm and 105 lb·ft (142 N·m) of torque at 2000 rpm with 6.48:1 compression.[4]

The L134 was phased out by the F-head Willys Hurricane engine beginning in 1950.



  1. ^ "Willys-Overaland Jeep advertisement". Life. 14 (7): 13. 15 February 1943. Retrieved 23 November 2014. 
  2. ^ a b Doyle, David. Standard Catalog of U.S. Military Vehicles (Second ed.). KP Books. p. 28. ISBN 9780873495080. Retrieved 23 November 2014. 
  3. ^ Zalog, Steven J. (2005). Jeeps 1941-45. Osprey Publishing. pp. 8–9. ISBN 9781841768885. Retrieved 23 November 2014. 
  4. ^ a b Statham, Steve (1999). Jeep Color History. Motorbooks. p. 24. ISBN 9780760306369. Retrieved 23 November 2014. 
  5. ^ a b c Green, Michael; Stewart, Greg (2005). Humvee at War. Zenith Press. p. 13. Retrieved 23 November 2014. 
  6. ^ Allen, Jim (2003). Jeep Collector's Library. Motorbooks, MBI Publishing. p. 227. ISBN 9780760314869. Retrieved 23 November 2014.