AMC Straight-4 engine

AMC Straight-4 engine

The American Motors Corporation straight-4 engine was used by a number of AMC, Jeep, and Dodge vehicles from 1984 through 2002.

* For an outline of all engines used by AMC see main|AMC Engines


American Motors devoted three years to the development of a new four-cylinder engine. According to Jeep's chief engineer, Roy Lunn, "unlike most engines available today [it] was not designed for passenger cars and then adapted for trucks. We specifically developed it with our Jeep vehicles and Eagle in mind. That's the reason that performance and durability were of such prime consideration from the very beginning." Although some of components were interchangeable between the AMC 258 cubic inch 6-cylinder and the new engine, the 4-cylinder was not a cut down version of the big six. Noted Roy Lunn, "There is some common competency, but the 4-cylinder includes many unique items such as its own electronics systems. It also has a shorter stroke and larger bore. The valves are larger and the pistons are new." Roy Lunn recalled: "We wanted as much displacement - for power and torque - as possible within the confines of bore centers of the tooling. The only parameter we could influence substantially was stroke. So we picked the largest bore and stroke in order to get 2.5 Liters." [ Ackerson, Robert C. (1991) "The 50 year History of the Jeep", Motorbooks, ISBN: 9780854295333.]

The AMC 150/2.5 L engine

The 2.5 L inline-4 was a shortened version of the 258 6-cylinder engine bored to 3.875 inches (99 mm) and de-stroked to 3.188 inches (81 mm). The block is basically the same as the legacy 258-cubic inch engine with a larger bore and the two center cylinders removed. The head featured a new combustion chamber and port design that was later used on the 4.0 L - the 2.5 L I-4 head was stretched by two cylinders in the center.

Instead of the standard AMC bell housing bolt pattern, AMC/Jeep engineers adopted the General Motors small V6 and four-cylinder bolt pattern (commonly used with GM's transverse-mounted powerplants) for their new engine, because the new AMC 2.5 replaced the four-cylinder engines that had been purchased from GM; and because AMC continued to buy the 2.8 L V6 from GM until the 4.0 L I6 was introduced in 1987. The four-cylinder and V6 shared the same drivetrain components, whereas stronger transmissions were needed for the new 4.0 L.

The AMC I4 first appeared in 1984 with the new XJ Cherokee. It was produced through 2002 for the Jeep Wrangler, as well as for the Dodge Dakota pickup that also used the AMC/Jeep designed four since 1996.

Output the final year was 121 hp (89 kW) at 5400 rpm and 145 ft·lbf (197 N·m) of torque at 3250 rpm using sequential multiple-port fuel injection (MPFI). For comparison, the 258 I6 provided 112 hp (83.5 kW) at RPM and 210 ft·lbf (285 N·m) of torque at 2000 rpm in its final year with the computer controlled carburetor.

For several years, the engine was detuned for the Wrangler; from at least 1992 to 1995, it produced 130 hp (97 kW) horsepower and 149 ft·lbf (202 N·m) of torque with 9.2:1 compression in the Cherokee and Comanche. [ Allpar]


This engine was used in the following vehicles:
* 1984-1986 Jeep CJ-7
* 1983.5-1984 AMC Eagle
* 1984-2000 Jeep Cherokee (XJ)
* 1986-1992 Jeep Comanche (MJ)
* 1987-2002 Jeep Wrangler (YJ/TJ)
* 1988-1989 Eagle Premier
* 1996-2001 Dodge Dakota

ee also

* AMC Straight-6 engine
* AMC V8 engine
* AMC Engines
* AMC/Jeep Transmissions
* List of Chrysler engines


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • AMC Straight-6 engine — The American Motors Corporation (AMC) straight 6 family of engines was used by a number of AMC and Jeep vehicles from 1964 through 2006.* For an outline of all engines used by AMC see main|AMC Engines195.6American Motors first straight six engine …   Wikipedia

  • AMC V8 engine — American Motors Corporation (AMC) produced a series of widely used V8 engines from the mid 1950s before being absorbed into Chrysler. Some continued well after the merger in Jeep vehicles until 1991.GEN 1 Nash/Hudson/Rambler V 8s (1956 1966)Many… …   Wikipedia

  • AMC Spirit — Infobox Automobile name=AMC Spirit manufacturer=American Motors (AMC) production=1979 ndash; 1983 assembly =flagicon|USA Kenosha, Wisconsin flagicon|Canada Brampton, Ontario, Canada flagicon|Mexico Mexico City, Mexico (VAM) class=Subcompact… …   Wikipedia

  • AMC and Jeep transmissions — American Motors Corporation (AMC) and Jeep used a variety of transmissions and transfer cases systems. This article covers all AMC (1954+) and Jeep (1946+) variants thru 1988, as well as legacy designs retained by Chrysler (and several other… …   Wikipedia

  • Straight-6 — The straight 6 or inline 6 engine (often abbreviated I6 or L6) is a six cylinder internal combustion engine with all six cylinders mounted in a straight line along the crankcase. The single bank of cylinders may be oriented in either a vertical… …   Wikipedia

  • AMC Gremlin — Infobox Automobile name = AMC Gremlin manufacturer = American Motors Corporation production = 1970 ndash; 1978 assembly = Kenosha, Wisconsin USA Brampton, Ontario, Canada Mexico City, Mexico (VAM) class = Subcompact body style = 3 door hatchback… …   Wikipedia

  • AMC Pacer — Infobox Automobile name = AMC Pacer manufacturer = American Motors (AMC) production = 1975 ndash; 1980 assembly =flagicon|USA Kenosha, Wisconsin flagicon|Mexico Mexico City (VAM) class = Compact body style = 2 door hatchback 2 door station wagon… …   Wikipedia

  • AMC Hornet — Infobox Automobile name = AMC Hornet manufacturer = American Motors Corporation production = 1970 ndash; 1977 assembly =Kenosha, Wisconsin, USA Brampton, Ontario, Canada Mexico City, Mexico (VAM) class = Compact body style = 2 door coupe 3 door… …   Wikipedia

  • AMC Concord — Infobox Automobile name = AMC Concord manufacturer = American Motors Corporation production = 1978 ndash; 1983 assembly = Kenosha, Wisconsin USA Brampton, Ontario, Canada Mexico City, Mexico (VAM) class = Compact body style = 4 door sedan 2 door… …   Wikipedia

  • AMC Matador — 1976 AMC Matador coupe Manufacturer American Motors Corporation Also called Rambler Matador (foreign markets) Production …   Wikipedia