1931 CUMMINS MODEL H TO THE 2002 N14

BY JIM ALLEN (WITH SPECIAL THANKS TO KEITH BAYLOR)

How do you get six exhaust pipes out of a four-cylinder engine? The experimental 135 hp two-stroke Model H race engine used a Cummins interpretation of the Uniflow system used by GM. On the block, you can see the inlet manifold lining up with the ported sleeves and inlet ports that were scavenged by a crankshaftdriven Switzer-Cummins blower at about 3 psi. On the exhaust side, the head was the standard H unit, but the Siamesed intake and the exhaust ports were all used to exhale—and that’s how you get six exhaust stacks on a four-cylinder engine. The pump was an updated SD. Persistent rumors state that Cummins tossed this engine into a river after the Indy race. Here’s proof that that is a completely busted myth.

Every manufacturing company has a foundational product. Sometimes, that product comes right away, but for the Cummins Engine Company, that foundational product came over a decade after its 1919 beginning. Its direct offspring continue in production today.

Much of founder Clessie Cummins’ early efforts with compressionignition technology involved the HVID system (pronounced “veed”). He quickly learned the limitations of HVID and moved past it, but his thinking also extended beyond engine designs and into engine markets.

First On-Road Engine

By the end of the 1920s, Cummins saw a diesel market in the automotive realm—“automotive” meaning anything operating on the highway. Due to technical barriers, automotive diesels were generally regarded as impractical in this era and weren’t being widely pursued. Working toward an achievement in that realm, Cummins repowered a used 1925 Packard limo with one of the company’s most modern engines—a four-cylinder Model U marine diesel. Normally, this engine made 40 hp at 900 rpm, but Cummins tweaked it to make 60 at 1,300; and, in January 1930, he went on the road to make some news.

The Model U wasn’t an optimal swap for a car. The engine was huge, heavy and slow turning, but it took Cummins to shows around the country on a few dollars’ worth of fuel. It opened a lot of eyes, among them Henry Ford’s. Ford was encouraging but suggested focusing on the truck market.

Cummins had already figured that out, but he also knew he had to make a splash, and cars made the biggest splash. While on the tour, he was invited to run a diesel car in the March 1930 Daytona Beach Speed Trials. The limo was too heavy, so he “souped-up” the Model U a little more and put it into a stripped Packard roadster. On March 20, 1930, the car set an official diesel-powered car record of 80.389 mph.

Built on September 15, 1932, this HA is approximately the 25th HA-600 production engine and is the earliest known surviving H-Series six-cylinder. It was used for the 1935 Daytona Beach trials. It was updated with improved manifolding and a supercharger, raising the power output to 300 hp at 2,100 rpm on about 8 psi boost. Most likely, the pump was tweaked as well, but other mods are likely. This engine runs but has not been apart in a lifetime, so the internals are a mystery. It’s unclear why an early engine was used in the modified #5 race car three years after it was built.