Joe Petrali’s 1937 Harley-Davidson Land Speed Record
In 1936, Harley-Davidson set out to build a factory land-speed motorcycle around its new overhead-valve Big Twin. The company started with a 1937 EL, the 61 cubic inch machine that would later be known by every rider as the Harley-Davidson Knucklehead.
The idea was simple enough: take the new EL, clean up the wind, put a hard rider on it, and go to Daytona Beach. The result was one of the best known factory speed machines Harley-Davidson ever built.
The 1937 Harley That Went to Daytona
The EL was still new when Harley-Davidson chose it for the job. The motor was a 61 cubic inch overhead-valve V-twin, a big step away from the flathead engines that had carried so much of the company’s road and police work through the early 1930s.
For a speed record, the factory did not need saddlebags, lights, road gear, or comfort. It needed the smallest hole through the air it could get while still keeping the motorcycle rideable on the beach. Daytona’s hard sand had already earned a reputation as a place where cars and motorcycles could stretch their legs before paved speedways took over.
The finished machine still looked like a Harley, but just barely. The tank badge was there, the V-twin was still hanging in the frame, and the rider still sat on top of it like a motorcycle. Everything else was aimed at speed.
Building Speed Into the EL Knucklehead
The front fairing was the most distinctive piece. Harley-Davidson took part of a gas tank, reshaped it, and used it over the front fork area. It gave the bike a blunt nose and a narrow face, with Petrali tucked in low behind it.
The handlebars were low and tight, putting the rider’s hands down out of the wind. The wheels were covered. The seat was set into the bodywork. Behind the rider, Harley-Davidson added a long tail section that turned the motorcycle into a kind of half-streamliner.
That tail was the part that looked fast standing still. It was also the part that caused trouble once the motorcycle got up into record speed. Streamlining was still a young game for motorcycles, and a shape that looked right in the shop did not always behave on the sand.
The Tail Fin That Had to Come Off
During testing, the rear bodywork caused vibration and instability at high speed. The bike was fast, but it was not steady enough with the tail fitted. Petrali was the rider who had to feel that through the bars, the seat, and the footboards.
The factory removed the tail before the actual record attempt. That left the front fairing in place and kept the motorcycle closer to a rideable machine. It also left Petrali with plenty of open air behind him, which makes the final number even better.
That little detail is what gives the 1937 machine its character. Harley-Davidson did not roll onto Daytona Beach with a perfect wind-tunnel shape. They built a fast motorcycle, found the part that was trying to hurt the rider, took it off, and sent Petrali back out.
Joe Petrali’s 136.183 MPH Run
Joe Petrali was the right man for it. He was not just a name hired for a photograph. Petrali was one of the great American motorcycle racers of the 1920s and 1930s, with national wins on boards, dirt, and hills. By 1937 he had already spent years making factory motorcycles do things that ordinary riders would have walked away from.
On March 13, 1937, Petrali took the streamlined EL onto Daytona Beach and ran 136.183 miles per hour. Some accounts call it an American record and others call it a world record, but the number that stuck was 136.183 mph on the sand at Daytona.
That was a serious number for a 61 cubic inch factory Harley in 1937. It also gave the new overhead-valve Big Twin something no sales brochure could match: a hard speed record with Joe Petrali’s name on it.
Harley’s Earlier Daytona Record Runs
The 1937 Petrali run was not Harley-Davidson’s only trip to Daytona in search of speed. Back in February 1920, the factory sent riders such as Leslie “Red” Parkhurst and Fred Ludlow to the beach with racing machines and official timing. That earlier effort put Harley-Davidson into the record business long before the Knucklehead existed.
That is why the 1937 machine is better understood as the famous EL Knucklehead factory land-speed record, not as Harley-Davidson’s beginning in speed-record work. The 1920 team showed what the factory racers could do on the beach. Petrali’s 1937 ride showed what the new overhead-valve Big Twin could do with streamlining and a fearless rider.
Daytona was the common thread. The beach had the distance, the surface, and the reputation. Before Daytona became a name tied mostly to the 200 and the speedway, the sand itself was the course. That old beach history is the backbone of Daytona Beach racing, from record runs to road racing.
Rollie Free and the End of the Eleven-Year Run
Petrali’s 136.183 mph mark stood for 11 years. In 1948, Rollie Free finally broke it at Bonneville on a Vincent. That is the run everybody remembers for the bathing suit, the prone riding position, and the rider stretched out flat behind the bars like he was trying to become part of the motorcycle.
Free’s Bonneville run belonged to a different setting and a different postwar speed age. Salt replaced sand. Speeds climbed. Streamlining kept getting more serious. But Petrali’s Daytona run still held its place, because it came out of the prewar factory racing world, with a new Harley Big Twin and a rider who had already earned his reputation the hard way. The later Knucklehead stroker known as The Brute belonged to that same postwar speed world, where salt, drag strips, and publicity runs pushed Harley speed into a rougher hot-rod age.
Indian would follow its own path into streamliner history, including the later Indian Arrow streamliner. The late 1930s were full of American companies trying to prove that their engines had more in them than road work and showroom talk.
The Petrali Knucklehead Legacy
The Petrali Knucklehead became one of those motorcycles that people remember even when they do not know every detail. The silhouette is enough: the fork fairing, the disc wheels, the low bars, the tank badge, and Petrali sitting there in light gear on a machine built for more than 130 miles per hour.
It also gave the Knucklehead a racing story right at the start of its life. The EL was not just a new road model with a different top end. In Petrali’s hands, it became a record machine on Daytona Beach.
That is why the 1937 run still belongs in any serious vintage racing archive. It sits at the point where factory racing, streamlining, beach records, and Harley-Davidson’s new overhead-valve Big Twin all crossed the same strip of sand.