General Motors is responsible for some of the greatest engines to ever see widespread use. The Iron Duke is a notable exception to that reality.

GM has produced some great engines in its day, including the famed 350 cubic inch small block V8. Here are some of the worst engines GM ever produced.

The result of this cut-and-paste engineering was a 2.5-liter pushrod straight-four engine that ran rough and sounded unpleasant but held together pretty well. Production of the Iron Duke ran from ...

The infamously weak, Pontiac-built Iron Duke engine was a 2.5-liter fuel-injected pushrod straight-four, which was essentially just one cylinder bank from a contemporary Pontiac V8.

Pontiac's 4-cylinder "Iron Duke" has been around for nearly five years now, and it has always held enormous potential as a high-performance engine.

With no manual transmission available (1988 was the final model year for a 5-speed Pontiac 6000) and engine choices limited to a 90-horsepower Iron Duke four-cylinder or a 130-horsepower 2.8-liter ...

Produced at the nadir of American performance, when fast-looking cars were made to suffer with wheezy, limp engines, the Camaro Iron Duke sauntered to 60 mph in an astonishing 20 seconds.

The Z-28 Camaro in 1984 came with a 5.0-liter V8 making a respectable 190 horsepower. Buyers who went with the base four-cylinder engine, however, got just 92 Iron Duke horses. Few did. Here's a ...