The mighty Offy, Indy’s winningest engine

Published On March 22, 2016 » 6088 Views» By Marshall Pruett » Blogs, IMS, IMS History, Indy 500

We’re chronicling 100 days of Indy 500 history on #SpeedRead leading up to the historic 100th Running. With 68 days to go, racing journalist Marshall Pruett continues his look back at milestone cars and technology.

More Pruett: Penske’s ’94 dominator | The “Fantastic” Turbine | Murphy’s Miller straight-8 | Yunick’s winged Watson More 100 days

Call it a Miller. Call it an Offenhauser or an “Offy.” Call it a Meyer-Drake. Call it a Drake-Sparks-Goossen, or by the acronym “DSG.” Whichever name you prefer, the little four-cylinder, double-overhead-cam engine won more Indianapolis 500s than any other model, did so while passing through the hands of some of the sport’s sharpest minds, and from their concerted efforts across more than five decades, the Offy dominated for a longer period than any other motor in the Speedway’s illustrious 105-year history.

Penned by Leo Goossen at Harry Miller’s base in Los Angeles, the 91-cubic-inch motor borrowed heavily from the four-cylinder DOHC Peugeot engines that won the Indy 500 in 1913 and 1914, and with the blended concepts of the French motor and the ideas emanating from Miller’s shop, the Miller triumphed multiple times at Indy before bankruptcy struck in the early 1930s. Miller employee Fred Offenhauser developed the engine using a marine engine variant of the Miller design to bring the motor to market, and by 1935, the Offy had won its first 500 in with Kelly Petillo behind the wheel of a Wetteroth chassis.

The first Offenhauser win came with Kelly Petillo in 1935. It's last would come 41 years later.

The first Offenhauser win came with Kelly Petillo in 1935. It’s last would come 41 years later.

To appreciate the Offy’s unparalleled quality, it won at Indy before WWII, won after the 500 resumed post WWII, won during and after the Korean War, before and during the Vietnam War, and by the time its last Indy win came in 1976 in a McLaren driven by Johnny Rutherford, seven United States presidents—from Franklin D. Roosevelt to Gerald Ford—had served.

Under the Offy name alone, the engine scored 27 Indy 500 wins, won every Indy 500 from 1947-64, and became the first turbocharged engine to win Indy in 1968 as the great Bobby Unser captured his first of three 500s.

The unflappable Offy in 1972.

The unflappable Offy in 1972.

“Boy, that Offenhauser engine, the ‘Offy’, it had to have been the most successful engine ever run at Indianapolis,” said Unser, who also won his second 500 with a turbo Offy in 1975. “Why, it was around for a long time before I arrived and it kept going until just before my last race. It was built so strong; it wasn’t like a lot of engines where everything bolts together and becomes fragile. Its head was an integral piece, and what I mean by that is the cams and the head were one unit. That made it so incredibly strong. And the block was also strong. You just couldn’t hurt the Offy unless you did something really stupid. It made an awful lot of torque all on its own for many years—decades—as a naturally-aspirated engine, and the thing with the Offenhauser is when they turbocharged it, it made more power than we’d ever seen.”

Parnelli Jones used an Offy to win the 1963 Indy 500, and by sheer coincidence, his efforts to turbocharge the dominant Cosworth DFV Formula One engine would spell the eventual end of the Miller-Offy-Meyer-Drake-DSG’s reign. The Offy’s 27 wins continue to stand as an unassailable target; of the engine manufacturers competing in May’s 100th Indy 500, Chevy (nine) would need to triple its current victory count, and Honda’s job (10) isn’t much easier.

Unser’s enduring fondness for the Offy in its final specification speaks volumes for the furious little powerplant.

“Oh, it was easily over 1,000 horsepower in qualifying with all that boost run through it; they made a lot more—a whole lot more—than 1,000 horsepower on the dyno,” he said. “But the problem was they would never last the 500 miles that way, so we raced with less than its full potential, but it was still an awful lot of power for a four-cylinder.”

Bobby Unser's winning Gurney Eagle of 1975 was powered by an Offy.

Bobby Unser’s winning Gurney Eagle of 1975 was powered by an Offy.


About The Author

Marshall Pruett

Marshall Pruett transitioned from more than 20 years as an open-wheel and sports car mechanic, engineer and team manager into his current role as a writer and reporter in 2006. Follow him @MarshallPruett []