page_title: 1994 Indianapolis 500
section_title: Mercedes-Benz 500I
hierarchical_section_title: 1994 Indianapolis 500 / Background / Mercedes-Benz 500I
context_page_description: The 78th Indianapolis 500 was held at the Indianapolis Motor Speedway in Speedway, Indiana on Sunday, May 29, 1994. The race was sanctioned by United States Auto Club, and was included as race number 4 of 16 of the 1994 PPG IndyCar World Series. For the second year in a row, weather was nary a factor during the month. Only one practice day was lost to rain, and pole day was only partially halted due to scattered showers. Warm, sunny skies greeted race day.
  Al Unser, Jr. won from the pole position, his second Indy 500 victory. Much to the surprise of competitors, media, and fans, Marlboro Team Penske arrived at the Speedway with a brand new, secretly-built 209 in³ displacement Mercedes-Benz pushrod engine, which was capable of nearly 1,000 horsepower. Despite reliability issues with the engine and handling difficulties with the chassis, the three-car Penske team dominated most of the month, and practically the entire race.
  While Unser won the pole position, Fittipaldi dominated most of the race, leading a total of 145 laps. On lap 185, Fittipaldi was leading the race, and was looking to put Unser a lap down.
context_section_description: The most notable off-season activity involved Penske Racing and Ilmor. In the summer and fall of 1993, Ilmor and Penske engaged in a new engine project. Under complete secrecy, a 209 in³ (3.42 L) purpose-built, V-8 pushrod engine was developed. Mercedes eventually came on board with the project, and badged the engine the Mercedes-Benz 500I. The engine was designed to exploit a perceived loophole that had existed in USAC's rulebook since 1991. While CART sanctioned the rest of the Indycar season, the Indianapolis 500 itself was conducted by USAC under slightly different technical regulations. This effort represented a rare instance during this era where considerable money and effort were invested in creating a powerplant specifically for the Indy 500 by a CART-based team.
  In an effort to appeal to smaller engine-building companies and independents, USAC had permitted "stock-block" pushrod engines (generally defined as single non-OHC units fitted with two valves per cylinder actuated by pushrod and rocker arm). The traditional "stock blocks" saw some limited use in the early 1980s, but became mainstream at Indy with the Buick V-6 by 1985. Initially, the stock blocks were required to have some production-based parts. However, in 1991, USAC quietly lifted the requirement, and purpose-built pushrod engines were permitted to be designed for racing from the ground up. Attempting to create an equivalency formula, both pushrod engine formats were allowed increased displacement of 209.3 cubic inches (3.430 L) instead of 161.7 cubic inches (2.650 L), and increased turbocharger boost of 55 inHG instead of 45 (1860 hPa instead of 1520).
  Team Penske tested and further developed the engine in secret in the winter and spring of 1994. Before Mercedes-Benz joined the effort, the engine was initially called the "265E", which followed Ilmor's standard naming convention for their dual overhead camshaft engine. This was ostensibly to maintain in-house secrecy of the pushrod project, from those working within Penske and Ilmor who were not made fully aware of it. It was mated with the in-house Penske chassis, the PC-23. It was introduced to the public in April, just days before opening day at Indy. Rumors quickly began to circulate that the engine was capable of over 1,000 hp (750 kW), which was up a 150-200 hp advantage over the conventional V-8s.
caption: 1994 Penske PC-23 Mercedes-Benz 500I
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