Jeep Tornado engine

The Jeep Tornado engine was the first post-World War II U.S.-designed mass-produced overhead cam (OHC) automobile engine.[1] The 230.5 cu in (3.78 L) straight-six was introduced in mid-year 1962, and replaced the flathead 6-226 Willys Super Hurricane that was in use since 1954.

Jeep Tornado
1963 Jeep Pickup FL engine-L.jpg
Also called
  • Tornado Jet (IKA)
  • Tornado Interceptor (Renault)
Displacement230.51 cu in (3,777 cc)
Cylinder bore3 1132 in (84.93125000 mm)
Piston stroke4 38 in (111.12500000 mm)
Block materialIron
Head materialIron
Compression ratio8.5:1 or 7.5:1
Power output
  • 140 hp (100 kW) at 4000 rpm or
  • 133 hp (99 kW) at 4000 rpm
Specific power
  • 0.61 hp/in³ or
  • 0.58 hp/in³
Torque output
  • 210 lb⋅ft (280 N⋅m) at 1750 rpm or
  • 199 lb⋅ft (270 N⋅m) at 2400 rpm
PredecessorWillys Super Hurricane
SuccessorAMC straight-6 engine
1963 Jeep Tornado engine

The Tornado engine was also manufactured in Argentina by Industrias Kaiser Argentina (IKA) from 1965 to 1973.


The development of a new engine for Kaiser Jeep for an entirely new vehicle began under Chief Engineer, A.C. "Sammy" Sampietro, in the late-1950s.[2] Sampietro worked under Donald Healey in Europe and focused on improving power output through better engine breathing.[2] The single overhead cam design was combined with hemispheric combustion chambers.[3] Mass production of the new engine began in 1962.

The Jeep Tornado engine was introduced in the Willys Jeep Wagon and truck models.[4] Six-cylinder versions built after May 3, 1962, received the 230 OHC "Tornado" engine, replacing the 226 L-head "Super Hurricane" I6.[5] It was made the standard engine in the completely new Jeep Wagoneer station wagons (today called SUV) and Jeep Gladiator pickup trucks that began production in the fall 1962 for the 1963 model year.[6]

The Tornado was the only U.S.-built overhead-cam engine in production at that time. The new engine was designed for robust, heavy-duty performance with maximum efficiency. Its excellent fuel economy was proven in tests with the Tornado-OHC engine having the lowest specific fuel consumption of all production gasoline engines on the market.[7]


The Tornado, like most Jeep engines, was undersquare for better low-speed torque. It had a 3 1132 in (84.93 mm) bore with a 4 38 in (111.13 mm) stroke. The standard version had an 8.5:1 compression ratio. Output was 140 hp (100 kW) at 4000 rpm and 210 lb⋅ft (280 N⋅m) of torque at 1750 rpm. A low-compression (7.5:1) version was also available, with 133 hp (99 kW) at 4000 rpm and 199 lb⋅ft (270 N⋅m) of torque at 2400 rpm. It was a "high-efficiency" engine with a conservatively rated power output.[8]

The new engine's overhead camshaft design was only one of the advanced features offered for the first time in a U.S.-designed and mass-produced engine.[8] The Tornado was a good engine; unfortunately, it was complex (by 1960s standards) and was discontinued in civilian vehicles in the U.S. in 1965. It continued to be used in military versions of the Jeep pickup, the M-715 and M-725, until 1969. These engines had block-mounted motor mounts, rather than the front cover mounts that were a cause of oil leaks on the civilian versions.[9]

One unique feature of the design was that the camshaft only had six lobes. One lobe operated both the intake and exhaust valve for each cylinder. This made engineering cam profiles a bit more difficult than conventional two lobe per cylinder (one per valve) designs, but allowed the valves to be better arranged for the cross-flow head. Valves were directly opposite their respective ports, and ports were short with wide radius turns.

Road tests of the new Jeep Wagoneer by Car Life magazine described the OHC six as "commendably smooth and quiet."[10] The engine accelerated the four-wheel-drive full-size station wagon (the SUV designation was not yet known) with an automatic transmission from 0 to 60 mph in 15.9 seconds.[10] Their tests recorded 17 mpg‑US (14 L/100 km; 20 mpg‑imp) on the highway and 14.5 mpg‑US (16.2 L/100 km; 17.4 mpg‑imp) in the city, that "certainly demonstrates the remarkable efficiency of the OHC engine."[10]


Production of this engine continued in Argentina by Industrias Kaiser Argentina (IKA) after 1965. The engine was used in a variety of Jeep vehicles and American Motors (AMC) passenger cars assembled under license.[11] The engine became best known for powering the IKA-Renault Torino, their version of the AMC Rambler American having unique styled front body parts that was built in Argentina from 1966 to 1981. It achieved international success in the 1969 Nürburgring 84-hour endurance race when a Torino placed third due to penalty points after covering 334 laps, the most of all the racers (c.9450 km/5868 mi.).[12][13]

The engine name was changed to "Torino" to match the car in 1973. It also received a major block and crankshaft refinement that year — seven main bearings instead of the original four. Industrias Kaiser Argentina was eventually bought out by Renault, and in 1975, the "IKA" name was dropped and it became "Renault Argentina". The Torino, Jeeps, AMC cars, as well as the Tornado engine itself, continued to receive upgrades over the years. Argentinian's Tornado engines raised up the power from 155 HP to 215 HP (street versions) and 250 HP to 350 HP (Racing versions). It was achieved by a new Cylinder head, which has improved the intake and exhaust ducts. Also adopted a new camshaft, a new exhaust manifold 3-1 / 3-1 type, two 2" diamenter exhaust pipes and 3 carburators Weber DCOE 45-45.

The Torino and the Jeep Tornado engine continued production through 1982. It was marketed as the "Tornado Jet", and later as the "Tornado Interceptor", in AMC automobiles.[11] From 1976 to 1982 they were the only non-Renault–designed cars and engines built by the French company.[14]


The Jeep Tornado engine was used in the following vehicles:

External linksEdit

  Media related to Jeep Tornado engine at Wikimedia Commons


  1. ^ "Kaiser Jeep". Ward's Automotive Yearbook. 26: 137. 1964. Retrieved 22 December 2013.
  2. ^ a b Allen, Jim (August 2006). "Back To The Future: The Strange Life of Jeep's OHC 230". Off-road Adventures. Archived from the original on 24 December 2013. Retrieved 22 December 2013.
  3. ^ Page, Ben. "Tornado 230 CI Engine Information / History". The International Full Size Jeep Association. Retrieved 22 December 2013.
  4. ^ Foster, Patrick R. (2004). The Story of Jeep. KP Books. p. 111. ISBN 978-0-87349-735-0. Retrieved 22 December 2013.
  5. ^ Allen, Jim (2004). Jeep. Motorbooks International. p. 111. ISBN 9780760319796. Retrieved 22 December 2013.
  6. ^ Inc, Time (30 November 1962). "Meet the beautiful brute - Jeep Gladiator (advertisement)". Life. 53 (23): 23. Retrieved 22 December 2013.
  7. ^ Foster, Patrick (January 2008). "1963 Jeep Wagoneer - Landmark Vehicle". 4-Wheel Drive & Sport Utility. Retrieved 22 December 2013.
  8. ^ a b "Overhead Camshaft Design is Feature of New Willys 140 H.P. 6-cyl Engine". Autodriver: 23. 1961. Retrieved 22 December 2013.
  9. ^ Allen, Jim (2007). Jeep 4x4 Performance Handbook (Second ed.). Motorbooks/MBI. p. 195. ISBN 9780760326879. Retrieved 22 December 2013.
  10. ^ a b c Auto Editors of Consumer Guide (29 August 2007). "1963-1992 Jeep Wagoneer and Grand Wagoneer". Retrieved 22 December 2013.
  11. ^ a b "Kaiser Industries in Argentina". Retrieved 25 March 2013.
  12. ^ Orosz, Peter (8 March 2011). "When Argentina ruled the Nürburgring". jalopnik. Retrieved 22 December 2013.
  13. ^ de Jong, Frank. "1969 Nurburgring 84hrs". Retrieved 22 December 2013.
  14. ^ "Renault Torino GR (1982 MY)". Retrieved 22 December 2013.