page_title: Iron Duke engine
section_title: Tech IV (1982-1990)
hierarchical_section_title: Iron Duke engine / Tech IV (1982-1990)
caption_attribution_description: English: In this exhibit at the REO Museum in Lansing Michigan you can see a 1990 GM Iron Duke engine with parts cut away to reveal the inner arrangement.
context_page_description: The Iron Duke engine is a 151 cu in Straight-4 piston engine built by the Pontiac Motor Division of General Motors from 1977 to 1993. Thereafter GM's 2.2 L OHV 4-cylinder replaced it across the entire lineup of vehicles that offered it. Although its original purpose was to serve as Pontiac's new economy car engine it was later adapted for use in wide variety of applications across GM's lineup in the 1980s.
context_section_description: Iron Dukes were fitted with fuel injection (TBI, 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 increased to 90 hp (67 kW).
  This was replaced by a swirl-port head with 9.0:1 (instead of 8.25:1) 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. Several significant changes were made in 1987, which included: an improved cylinder head, intake manifold and throttle-body fuel injection module, a more-modern serpentine belt with an automatic spring-loaded tensioner for the accessories, and a Distributorless Ignition System (DIS). This revision to the engine increased power to 98 hp (73 kW). In 1988, a balance shaft was added to smooth engine vibrations. Up to this point, the engine incorporated a 'dogbone' upper front engine mount secured to the cowling of the vehicle's hood latch, aiding in controlling the vibration. Further improvements in later years included new pistons, rods, crankshaft, and an in-pan oiling system. The most powerful variant of the Tech IV raised the rev limit to 5500 rpm, and achieved 110 hp (82 kW). The Tech IV uses the same bellhousing pattern as the 2.8 L 60-Degree V6. Over the years, the Tech IV engine has proved to be a reliable workhorse for owners when not pushed to its limits. All 1978-1990 Iron Duke engines used a micarta camshaft gear that meshed directly with a steel gear on the crankshaft. 1991-92 VIN R and U engines used a timing chain instead.
  Applications:
  1982–1985 Chevrolet Camaro, Pontiac Firebird
  1982–1989 Chevrolet Celebrity
  1982–1991 Pontiac 6000
  1982–1992 Buick Century, Oldsmobile Cutlass Ciera
  1984–1988 Pontiac Fiero
  1985–1987 Chevrolet S-10 Blazer, GMC S-15 Jimmy
  1985–1993 Chevrolet S-10, GMC S-15/Sonoma
  1985–1990 Chevrolet Astro, GMC Safari
  1985–1987 Buick Somerset
  1985–1991 Pontiac Grand Am, Oldsmobile Cutlass Calais
  1986–1991 Buick Skylark
  1987–1994 Grumman LLV (USPS delivery vehicle)
  1990–1992 Chevrolet Lumina
caption: 1990 GM Iron Duke engine with parts cut away to reveal the inner arrangement
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