The Iron Duke: Gm's Unkillable Engine That Never Got The Respect It Deserved

By nan mid-1970s, General Motors recovered itself successful situation mode during nan aftermath of nan OPEC lipid situation and an onslaught of high-quality, fuel-efficient cars from Japan. GM's first subcompact vehicle, nan Chevrolet Vega (one of which was freed from a clip capsule this year), had been an unmitigated disaster. Plagued by value and reliability issues, including pinch nan Chevrolet-designed "2300" four-cylinder motor pinch an exotic sleeveless aluminum artifact and cast-iron head, nan Vega eroded user spot and near GM scrambling.

However, it was clear this flawed motor creation was not going to do nan dense lifting for GM going forward. The lipid situation had sparked captious GM conveyance downsizing programs, specified arsenic nan compact X-body cars, which were successful improvement and group to debut for 1980. Meanwhile, a caller four-cylinder motor program, to beryllium branded nan "Iron Duke," was already underway astatine Pontiac. The intent was to reside nan shortcomings of Chevrolet's grounded 2300 motor design.

It was Pontiac technologist John Sawruk who utilized lessons learned from nan failures of nan Chevrolet Vega to create an all-new four-cylinder motor design, internally known arsenic nan "Formula Engine." The look sanction was derived from nan project's 5 engineering goals: minimizing sound and vibration, maximizing usable power, and providing fantabulous durability, driveability, and substance economy.

The architecture of nan Iron Duke motor drew connected nan proven engineering of Pontiac's V8 engines, including a cast-iron artifact and head, akin bore and stroke, heavy-duty bearings, and an overhead-valve design. Noise and vibration were minimized by implementing a short changeable for little piston travel, agelong connecting rods for smoother movement, and all-aluminum pistons for little reciprocating mass. Power transportation was optimized for little rpm cognition to guarantee responsiveness successful mundane driving.  With a displacement of 2.5 liters, first Society of Automotive Engineers nett output was 87 horsepower and 128 pound-feet of torque.

To region itself from nan ill-fated Chevrolet 2300 four-cylinder engine, Pontiac marketed its caller motor arsenic nan "Iron Duke" erstwhile it was introduced for 1977. It debuted successful respective Pontiac models, including Phoenix, Ventura, Sunbird, and nan Chevrolet Vega's rebadged sister model, nan Pontiac Astre. Meanwhile, nan Vega soldiered connected pinch nan notorious 2300 motor for its last year. The Iron Duke was subsequently introduced successful nan Vega-derived H-body Chevrolet Monza and Oldsmobile Starfire for 1978.

The Iron Duke would statesman to rotation retired crossed a wide array of General Motors vehicles, including nan X-, N-, and A-body compact and midsize car lines. The Iron Duke besides saw work arsenic nan guidelines motor successful nan compact Chevy S10 Pickup/Blazer, GMC S15 Sonoma/Jimmy trucks, and Chevy Astro and GMC Safari minivans. However, producing only 90 horsepower, nan Iron Duke appeared astir retired of spot arsenic nan guidelines motor successful nan third-generation Chevrolet Camaro and Pontiac Firebird introduced for 1982.

GM besides arranged deals to proviso different conveyance manufacturers pinch nan ubiquitous Iron Duke engine. Without a four-cylinder motor creation of its own, American Motors built an motor designed by VW, and purchased engines outright from GM during nan 1970s and 1980s. Iron Duke engines powered respective AMC models betwixt 1979 and 1983, including Spirit, Concord, 4WD Eagle, and Jeep CJ. The first RWD configuration of early Iron Duke engines facilitated easy adjustment to these vehicles. 

Perhaps nan champion testimonial to nan durability of nan GM Iron Duke motor was nan U.S. Postal Service's Grumman Long Life Vehicle (LLV). The LLV accommodated nan Iron Duke motor by design, utilizing a modified Chevrolet S10 ladder framework nether its civilization aluminum body. Manufactured from 1986 to 1994, The Grumman LLV continued good past its original expected work life of 24 years, logging hundreds of thousands of miles nether utmost conditions (though immoderate later LLVs utilized a Chevrolet 2.2 liter engine). The LLV is still successful work coming arsenic it awaits its long-overdue replacement, nan goofy-looking caller Oshkosh NGDV.

Right retired of nan gate, nan low-revving, gravelly-sounding Iron Duke was critically panned by nan automotive press. Unrefined characteristics, including driveability issues, exuded mediocre quality. The Iron Duke jeopardized nan motorboat of nan Pontiac Fiero successful 1984 pinch catastrophic motor nonaccomplishment and motor fires. This was attributed to some manufacturing defects and creation modifications for nan Fiero's mid-engine layout. Unlike its proud work successful nan remainder of nan GM lineup, nan Iron Duke formed a acheronian protector complete nan estimation of nan Fiero and yet hastened its demise. 

The Fiero was a footnote successful nan Iron Duke's history, though, arsenic nan motor proved its mettle complete time. The Iron Duke roseate to prominence successful respective racing bid during nan 1980s, acknowledgment to a catalog of "Super Duty" capacity parts offered by Pontiac. According to nan August 1986 rumor of Hot Rod magazine, "Super Duty engines, arsenic they are decently called, person made a sanction for themselves successful everything from title IMSA GTP racing to powerboat racing..." Additionally, Hot Rod said nan Iron Duke dominated low-level NASCAR racing, erstwhile "Super Duty engines virtually ain nan Charlotte/Daytona Dash series, wherever 36 retired of 46 entries astatine this year's Daytona opener were Pontiac-powered."

Engineering improvements continued to heighten nan accumulation Iron Duke. With nan preamble of throttle-body substance injection for 1982, GM rebranded nan Iron Duke arsenic nan "Tech IV." Additional updates included a big of soul improvements by 1985, and a serpentine thrust loop successful 1987. The biggest refinements came successful 1988, pinch nan summation of distributorless ignition and equilibrium shafts to amended capacity and further quell vibrations. The Tech IV persisted arsenic a guidelines motor offering successful galore GM vehicles into nan early 1990s. 

GM gradually phased nan Iron Duke/Tech IV retired successful favour of nan Chevrolet-designed 2.2-liter four-cylinder engine, ending its 16-year accumulation tally successful 1993. Meanwhile, nan modern dual-overhead-cam Quad 4 motor from Oldsmobile debuted successful 1987, marking nan adjacent section of GM four-cylinder engines. In nan end, nan venerable Iron Duke proved to beryllium nan economical, durable workhorse General Motors needed during a tumultuous clip of downsizing and strict Corporate Average Fuel Economy requirements.