The all-conquering Penske PC23/Mercedes
For the author, the star of the Performance Racing Industry (PRI) show tribute to the 50th anniversary of Team Penske and their success in the Indianapolis 500-mile race were the Penske PC-23B and Mercedes-Benz 500I engine owned by the Penske Collection.
By the mid-nineteen nineties, the sanctioning war of the nineteen eighties was settled, largely in favor of the Championship Auto Racing Teams (CART) group. The United States Auto Club (USAC) gamely hung on in championship auto racing - it sanctioned only one championship car race each year, but it was the biggest race of the year- the Indianapolis 500-mile race
Under the guise of encouraging participation by automobile manufacturers, and smaller teams and independents, the USAC rulebook had for years included a provision for "stock-block" pushrod engines limited to two valves per cylinder actuated by pushrod and rocker arms. The traditional "stock block" engines such as fuel-injected small-block Chevrolet engines appeared on occasion but a new “stock block” arrived at Indianapolis in 1984 – the 209 cubic inch turbocharged Buick V-6.
Cars powered by Buick V-6 engines set new one- and four-lap speed records and gained the top two starting positions in 1985. Scott Brayton set a one-lap record of 214.199 miles per hour (MPH) and Duane “Pancho” Carter won the pole with a new four-lap average of 212.583 despite the fact that the 800 horsepower Buick engine in Carter’ March chassis broke on the final straightway of his 10-mile qualifying run. Buick engines continued to return to Indianapolis year after year and while the engines generally were fast over short runs due to the higher allowed turbocharger boost levels for the “stock block” engine but the engine’s reliability remained a problem.
In 1991, USAC relaxed the previous rulebook requirement that “stock block” engine use some production parts which was designed to help the Buick teams to develop more robust parts to extend durability, but also opened the door for purpose-built pushrod engines. Since USAC only sanctioned one race construction of such engine was not considered economically viable.
In 1992, Buick’s final year of factory support, Roberto Guerrero in a car owned by drag racing king Kenny Bernstein demolished the one-and four-lap track records with a single lap of 232.618 MPH and a ten-mile average of 232.482 MPH. The starting field of the 1992 ‘500’ featured eleven Buick-powered cars, but Guerrero was one of five Buicks eliminated by crashed (his on the parade lap) and four Buicks blew up during the race.
The lone bright spot in the 1992 ‘500’ was Al Unser’s achievement as the first driver to finish the entire 500 mile distance with a car equipped with a Buick “stock block” engine. After Buick pulled out, the V-6 program was purchased by home improvement store magnate John Menard who rebranded the engine as the Menard.
During late 1993 and early 1994, in an audacious effort, Penske Racing in partnership with Ilmor Engineering designed and built a “clean sheet” pushrod engine code named the Ilmor 265E that carried the Mercedes-Benz nameplate. As related in the book Beast written by Jade Gurss, the Mercedes 500I 72-degree V-8 engine was tested and developed by Penske Racing in secret and unveiled to the public just a month before the race. While many people were shocked by the engine’s 1000+ horsepower output, but even more impressive was the engine’s output of over 580 foot/pounds of torque at 8000 revolutions per minute (RPM). Roger Penske had pulled off the ultimate ‘Unfair Advantage.’
For 1994, Nigel Bennett has designed the PC-23 which for the CART series used the Ilmor Indy V8 but the PC-23 had to be modified to accommodate the Mercedes-Benz 500I engine namely the bodywork and gearbox and the version raced at Indianapolis and displayed at PRI 2016 is known as the Penske PC-23B. Before arrival at Indianapolis, Penske teammates Al Unser Junior and Emerson Fittipaldi had won the two previous CART races in their PC-23s equipped with the Ilmor 265D engines.
At Indianapolis, the dominance was obvious from the moment that the first of the three Penske Mercedes-Benz powered PC-23B cars appeared on track on the first day of practice, particularly in regards to trap speeds on the backstretch where the PC23B consistently exceeded 244 MPH.
On the first day of time trials May 14 Al Unser Junior posted a 228.011 MPH four-lap average, but a rain shower delayed Emerson Fittipaldi’s qualifying run until the following day, and he posted a 10-mile average of 227.303 MPH for the outside of the front row. The chances for all-Penske front row had been spoiled when Paul Tracy crashed his PC-23B/Mercedes-Benz in practice on Friday. Tracy qualified later on Sunday May 15 at 222.710 MPH in the 25th starting position.
At the drop of the green flag on May 29, Unser Junior and Fittipaldi ran away and hid from the rest of the field, as “Little Al’ led the first 23 laps before he pitted. Unser stalled his engine in the pits and Fittipaldi took over and eventually led 145 laps. Tracy was never a factor and fell out with mechanical failure after 92 laps.
At one point Fittipaldi the defending Indianapolis ‘500’ champion had Unser down one lap, but Unser battled back and unlapped himself on lap 183. On lap 185, Fittipaldi pushed too hard through turn four to re-pass Unser and crashed hard into the outside retaining wall. Unser cruised home for his second Indianapolis 500-mile race victory and Penske’s tenth of sixteen to date.
Al Unser Junior's autograph from the 2016 PRI show
USAC reacted almost immediately to the Penske rout as on June 13, 1994, it was announced that the turbocharger boost of the purpose-designed pushrod was reduced from 55 to 52 inches of mercury while “production-derived” engines like the Buick/Menard were allowed to keep their 55 inches of “boost.” Before the Buick/Menard engine was obsolete due to a formula change after the 1996 Indianapolis ‘500,’ the engine produced 950 horsepower which Tony Stewart used to power his Lola/Menard to the 1996 Indianapolis ‘500’ pole position.
Testing revealed the Mercedes-Benz 500I pushrod engine was still competitive with 52 inches of “boost” and plans were put in place to build enough engines to supply the entire starting field for the 1995 Indianapolis ‘500.’ That all changed on August 10 1994 when USAC suddenly announced another reduction of maximum boost level for purpose-design pushrod engines back to 48 inches of mercury which made the Mercedes-Benz engine at best average if not uncompetitive and the production plans were scrapped. The PC23B and Mercedes-Benz 500I both became museum pieces and wound up displayed at the Penske Racing Museum in Scottsdale Arizona.
For many people the 1994 Indianapolis 500 was the pinnacle of success for the Penske PC-23 chassis, but that overlooks the tremendous success also experienced on the CART circuit Penske PC-23 cars won six straight CART races between April and mid-July 1994, and overall twelve of sixteen 1994 CART races.
Penske Racing swept the top three positions in CART points; Al Unser Junior won eight races to capture the PPG Cup (the sixth for Penske) while Fittipaldi finished second with one race win nut ten finishes better then fourth. Paul Tracy in his first full-time CART season finished third as he scored three race wins that included the final two races of the season.
Unfortunately for Penske Racing in just one season they went from the proverbial “penthouse to the outhouse” as the 1995 PC-24 was not anywhere near as good a car as the PC-23; Unser Junior scored just three wins and Fittipaldi one before Emerson’s career ended with a crash at Michigan International Speedway in July 1995. The biggest disappointment for the PC-24 came at the Indianapolis Motor Speedway as neither Unser nor Fittipaldi qualified for the 33-car starting field.
USAC’s 1994 “politically motivated move” (according to Roger Penske) regarding pushrod engine boost levels combined with the creation of the “Indy Racing League” on March 11, 1994, would have long-term future impacts on United States championship auto racing and Penske Racing which we will cover in a future article on the Penske Dallara IR2.
All photos by the author