Offenhauser. The Greatest Racing Engine Ever Built?
No other engine has been as dominant as the mighty Offenhauser engine. In a racing series where innovation was applauded and teams looked at every aspect of engine design to gain an edge, Offy engines managed to stay at the top, compiling an unmatched record of wins in open wheel oval track racing.
According to Ed Justice Jr., whose Justice Brother’s Museum houses a dozen Offenhauser engines, “No story of the incredible Offenhauser engine should go without mentioning the amazing backstory that got us to it’s place in history.”
If Offenhauser engine isn’t the best racing engine of all time, What is?
– Stewart Van Dyne
The Offenhauser Design Inspiration
“The road to the creation of the Offenhauser engine started literally at the earliest days of automotive development when three French drivers/engineers convinced Peugeot to build a twin-cam engine of their design,” adds Justice.
All three engineers, Paolo Zuccarelli, Jules Goux and Georges Boillot were 27 years old when they presented the idea to Peugeot. Goux is better known as the 1913 Indy 500 winner. Their design featured two overhead cams and four valves per cylinder, a departure from the typical racing engines of the day that relied on bigger displacement for power.
“During World War 1, parts for a Peugeot engine could not be acquired from France for the 1914 season. The engine was taken to Harry Miller’s shop for service and was cared for by Miller’s machine shop supervisor, Fred Offenhauser,” says Justice. “Miller and Offenhauser saw many benefits in the Peugeot design which later served as the basis of the Miller racing engine. The Miller engine later evolved into the famed Offenhauser engine which owes much inspiration from the early Peugeot Grand Prix racing engines.”
1933 – 255 Original Offenhauser 4 cyl twin cam
- Bore: 4.250”
- Stroke: 4.50”
- CID: 255.38
- C/R: 10:1
- Weight: 325 lbs.
- HP: 250 @ 5,200 rpm
1958 – 255 Low Tower
- Bore: 4.28”
- Stroke: 4.38”
- CID: 251.89
- C/R: 15:1
- Weight: 452 lbs.
- HP: 325 @ 6,600 rpm
1969 – 159 Offenhauser
- Bore: 4.030”
- Stroke: 3.125”
- CID: 159.520
- C/R: 8:1
- Weight: 360 lbs.
- HP: 820 @ 9,500 rpm
1974 – DGS Offy / 1975 – Drake-Offy
- Bore: 4.281”
- Stroke: 2.75”
- CID: 158.25
- C/R: 8:1
- Weight: 370 lbs.
- HP: 1000 @ 10,000 rpm
“It was at Miller where Offenhauser became friends with Leo Goosen, who was a young draftsman that went to work for Miller in 1919. Goosen would work for Miller and Miller’s successors until his death in 1974,” adds Justice.
Goosen laid out Miller and Offenhauser’s concepts into drawings that can only be described as works of art. These precursors to modern day 3D computer drawings played a crucial role in the Offenhauser engine design.
“As far as the Offenhauser engine, it’s figured that perhaps Fred Offenhauser built 150 racing engines. The Offenhauser was one of the most long-lived engines to ever power racing cars and you would be hard pressed to find another engine that lasted so long and was so successful,” says Justice.
How Dominant Were The Offenhauser Engines?
Record keeping at local tracks have been sketchy at best, but in America’s elite racing series, the AAA and USAC Champ Cars, and in America’s greatest race, the Indianapolis 500, there is plenty of data to support Offenhauser’s claim of greatness.
Offenhauser’s 251.92ci 4-cylinder made its way to daylight in 1933. Then the Offy started showing up at the tracks where it won consistently. In 1935 Kelly Petillo chalked up Offy’s first win in America’s great race, yet the powerful little mill remained a competitive race engine in the Indianapolis 500 into the mid-70s.
Offenhauser lived to see his mechanical design win the Indianapolis pole with Johnny Rutherford and Gordon Johncock win the race in another Offy-powered car at Indy in 1973. Offenhauser died later that year just before turbo boost rules brought an end to the Offy dynasty.
- Despite the Indy rule changes that reduced the Offenhausers to “also-rans,” Johnny Rutherford put the historic engine back in the brickyard’s victory lane in 1976. This marked the 27th win in 41 attempts. (65.9% win rate)
- From 1947 through 1964, Offenhauser engines powered the winning cars in the Indianapolis 500 (17 straight years).
- From 1950 through 1960, Offenhauser-powered cars not only won the Indy 500 but also claimed all three podium positions, winning the pole in 10 of the 11 years.
- From 1946 to 1969, Offenhauser engines won 245 Champ-car races.
What Makes Offy Engines The Best Ever?
Stewart VanDyne of Van Dyne Engineering, owner of the Offenhauser engine rights, patterns and tooling, states matter of factly, “If Offenhauser engine isn’t the best racing engine of all time, what is?”
One of the biggest keys to Offy’s success was power. The 251.89 twin-cam 4-cylinder with 15:1 compression ratio could produce as much as 420 horsepower at 6,6oo rpm.
“They sold a base race engine that many teams put their own twist on it,” says VanDyne.
Some variants of the engine were made to produce up to three horsepower per cubic inch. In an age when muscle cars were shooting for the magical one horsepower per cubic inch, three-times that amount was astounding.
Another reason for the engine’s success was reliability. The engine was manufactured as unit construction, which meant that there was no separate cylinder head. As such, the engine was not vulnerable to head gasket or cylinder stud problems and allowed for higher cylinder pressures.
The single factor that made the Offenhauser engine a favorite with race teams was its affordability. Private race teams could easily buy an Offenhauser engine, install it in a chassis, go to Indy and be competitive.
Miller to Offenhauser
Prior to Offenhauser’s reign of dominance, Miller engines were the racer’s choice at Indy. From 1922 to 1934, Millers won 10 of the 13 events held at the brickyard. When Miller went bankrupt, Fred Offenhauser bought the rights to many of Miller’s engines. Offenhauser changed things up in 1935. Engines bearing his name at the Indy 500 incorporated several changes from the Miller 255 and the Offenhauser engine stood on its own accord. Winner Kelly Petillo’s Offy was a special “low” block that measured 10.625 inches actually displacing 262ci. Later versions of the 255 were 0.46875-inches taller from the crankcase to the top of the block. Offenhauser also made his 255 bearing journals 1/8-inch larger than the orginal Miller 255. Taking first and second place in the Indianapolis 500 put Offenhauser solidly on the racing map.
“The engine was simple and durable,” says Van Dyne. “I’ve seen, and been a part of, rebuilding an Offenhauser over a 55-gallon drum at the track. All you need is a hoist and a torch to heat up the assembly. It’s just an easy engine to repair.”
Varients of Offenhauser
Offenhausers were so dominant that several other engine designers often went to Fred Offenhauser and Leo Goosen to incorporate and manufacture new engines based off of the Offenhauser design. Joe Lencki, of ZMax Micro-Lubricant fame, was one of those designers. Lencki took his idea for a two-valve per cylinder, hemispherical combustion chamber, 6-cylinder 270ci racing engine to Offenhauser. The Offenhauser plant built the engine, which looked very much like the Offy 270 with two extra cylinders. Lencki’s engines worked well but always ended up in wrecked cars at the brickyard – victims of bad luck. Lencki approached Goosen in the 1960s to design a turbocharged version of his straight-6, but it never came to be. From 1938 to 1963, Lencki spent $200,000 on engine development and kept all of his engines and patterns until the day he died. The Smithsonian and Indianapolis Speedway Museum were promised his cars and engines, but they were never delivered.
Thorne Engineering, headed by Joel Thorne, teamed with engine builder Art Sparks to develop their own version of the Offy engine. Another little 6-cylinder engine, Sparks utilized Leo Goosen’s talents with his own engineering solutions to produce an engine that could have challenged Offenhauser for dominance of the speedway. Sparks hired many of the ex-Miller employees and had access to Thorne’s machine shop. Spark’s engines did so well that orders came in from several buyers but Thorne refused to let Sparks sell any of the engines to other competitors. Art Sparks continued to play a role in refining the mighty Offy engine. Offenhauser’s last version of a racing engine was a combination of engineering ideas from Drake, Goosen and Sparks (Offenhauser DGS).
A. J. Watson had Meyer-Drake cast blocks that reduced the height of the Offy 270 to 10.93 inches with more metal around the bottom of the bores. Watson’s “low-tower” blocks became one of the most successful modifications to the Offy engines with it’s shorter stroke, higher rpm mod. When USAC changed the displacement limit from 274-inches to 256-inches in 1957, the “low-tower” block was the popular choice by almost all teams.
Dale Drake and Lou Meyer bought the engine company from Fred Offenhauser in 1946. Immediately the company became more business-like and better records were kept. Drake was no stranger to automotive parts manufacturing or Offenhauser. Drake’s father, J.A. Drake developed a high quality forged valve for automobile engines which he marketed under the Jadson Motor Valve Company name. Harry Miller was one of his largest customers. Leo Goosen stayed on with Meyer and Drake as Chief Engineer. The solid base engine design of the Offy stayed as it was for the next ten years. However, there were some minor improvements beginning with replacing hand poured babbitt bearing with Clevite bearing inserts. This greatly sped up engine building and repair. The cam drive gears were beefed up by changing from 12 to 10 pitch in 1947, making the already reliable engine even more dependable at racing rpm.
The Drake-Offenhausers continued to be a very successful engine through the middle 1970s, even with the ever-changing rule restrictions imposed by USAC. Other than power-adders like turbos, the basic engine design stayed the same throughout the entire era. Minor things like piston-ring packages were changed to handle the boost pressure when turbos were added, but the basic design remained as it had been when Fred Offenhauser produced the first block in 1933.
Offenhauser is the greatest racing ever built based on several factors. First and foremost, from it’s first Indy win in 1935 to it’s last win in 1976, the engine basic engine design remained the same. Secondly, the engine was simple and durable. It was built to last as evident by the amount of Offenhauser engines still running in vintage racing today. “They don’t build ‘em like they used to,” is an appropriate saying when referring to the racing engines. Finally, Offenhauser engines were affordable in their time, and very easy to modify to meet the individual racing teams needs.
In today’s terms, a 4-cylinder engine is often thought of as an economy engine. In the 1930s, Harry Miller thought of the twin-cam 4-cylinder engine as a better engine than the larger displacement, multi-cylinder engines. Time has marched on to prove Miller, Offenhauser and Drake correct in their higher-revving belief that 4-cylinder engines could dominate at the track. With Stewart Van Dyne owning the engine rights, patterns and name, it is certain that it is only a matter of time before the next Offenhauser engine block rolls off of the assembly line. It is also certain that the engine design will be the same basic Offenhauser block that first saw daylight in 1933. That is why the Offenhauser engine is the greatest racing engine ever built.