gm iron duke engine

The Iron Duke (also called the 2500, 151, Pontiac 2.5, Cross Flow, and Tech IV) was a 2.5 L (151 in³) I4 piston engine. All Iron Dukes were built by Pontiac beginning in 1977 and ending in 1993. Jeep also used it (as the Hurricane) in the Jeep CJ. It used an iron block and head, pushrods, and had a 4 in (101.6 mm) bore and 3 in (76.2 mm) stroke. The Iron Duke is often confused with Chevrolet's Stovebolt-derived 153 from the 1960s Chevy II, but the engines are entirely different. One thing that both share is the Chevy Small-Block bell housing bolt pattern. Applications:

p (kW)	lb.ft (Nm)
978	85 (63)	123 (167)
979	90 (67)	128 (173)
980	86 (64)	128 (173)

LS6

The LS6 was a 151 in³ (2.5 L) I4 engine produced from 1978 to 1979.

LS8

The LS8 was a 151 in³ (2.5 L) I4 engine produced from 1979 to 1979.

LX6

The LX6 was a 151 in³ (2.5 L) I4 engine produced from 1977 to 1978.

LX8

The LX8 was a 151 in³ (2.5 L) I4 engine produced from 1979 to 1980.

Crossflow

Cross-flow cylinder heads were added in 1980, leading people to refer to this version as the crossflow. Output stood at 90 hp (67 kW).

Hurricane

The Jeep Hurricane was used in the Jeep CJ for a time. Output was 82 hp (61 kW). Applications:

1980-1983 Jeep CJ-5
1980-1983 Jeep CJ-7

Tech IV

Iron Dukes were fitted with fuel injection (via a single injector in the throttle body) in 1982. This version was christened the Tech IV, though Car and Driver later ridiculed it as the low-Tech IV. Power output remained at 90 hp (67 kW). This was replaced by a swirl-port head with 9.0:1 (instead of 8.2:1) compression ratio in 1984 for a 2 hp (1.5 kW) gain. Other additions for 1985 included roller lifters, improved bearings, and a new crankshaft. A more-modern serpentine belt and crank-triggered ignition was added in 1987. The engine was updated one final time the next year with balance shafts, new pistons, rods, crankshaft, and an in-pan oiling system. This 1988 Tech IV produced 98 hp (73 kW). Applications:

1985-1993 Chevrolet S-10 Blazer/GMC S-15 Jimmy
Pontiac Fiero

Racing versions

Though not a production engine, the Super Duty 4 racing engine was notable and widely publicized at the time. It was the basis for NASCAR's Touring Car series. Cosworth also produced a 16-valve head for the Iron Duke.