We hit the wall on the 5.9L Cummins at a little over 400 horsepower because the intake side was holding the engine back. The fix was not more guesswork in calibration. It was airflow. We ditched the stock manifold, opened up the intake side, and built a side-draft manifold so the head could actually get the air it needed. That change took the combination to about 540 horsepower, and with the rest of the airflow and turbo work sorted out, the engine made 735 horsepower at about 3,100 rpm. More important, the layout delivered the kind of cylinder-to-cylinder air distribution we were after in a serious race engine. That package went into a full street-driven truck, ran a 217 mph two-way average with a 222 mph one-way best at Bonneville, and proved what the Cummins platform would do when the intake finally got out of the way.
Gale Banks traced the idea for the diesel land-speed truck back about 24 years to a conference in the Long Beach area, where he met John Stang. At the time, Stang was running Cummins' skunk works and was involved with both a new V8 diesel program and the common-rail version of the 5.9-liter that would later appear for the 2003 model year. This was around mid-2001. Banks proposed an ambitious idea: take a common-rail diesel to 300 mph. To establish credibility, he described his streamliner, which had already run 382 mph using a 300-cubic-inch Donovan engine, a 12-71 blower, nitromethane and alcohol, and a three-speed automatic. The car itself, he said, was essentially a dart aerodynamically.
After showing Stang photos of the streamliner, Banks was invited to visit the skunk works near Cummins in Columbus. There he learned more about the V8 program, of which only a few engines had been built, and also examined the common-rail development engines. His conclusion was that the common-rail injection technology was the more compelling opportunity. He liked the V8, but believed the common-rail 5.9 had a real customer and a stronger future. In his view, Cummins needed this new engine technology to succeed, and a high-profile speed-record effort could help energize the brand and attract younger and more institutional investors at a time when Cummins stock was trading unusually low, around $27 per share.
Banks framed the project as a modern version of Clessie Cummins' original promotional strategy of putting a large diesel into an automotive-sized vehicle and using speed and endurance to prove its worth. Rather than build another pure race car, he wanted to do it with a pickup truck. The plan was to reduce frontal area, heavily rework the suspension and chassis so the truck would be stable at speed, and install a large quick-change rear end. Cummins agreed to support the concept in a limited way. There was no budget for the build, but the company did provide used dyno engines. Banks' response was simple: if they were not blown up, they were usable.
Cummins prepared one of the engines with a larger turbocharger and some tuning changes before shipping it to Banks in Azusa, California. Cummins measured about 404 horsepower on its dyno; Banks then tested the same engine and saw roughly 402 horsepower, close enough to confirm that both sides were working from the same baseline. Banks also insisted that the truck remain streetable. He wanted it capable of towing the pit trailer carrying tools, a workbench, wheels and tires, and quick-change gears. The project therefore began not as a single-purpose race engine, but as a street-driven diesel pickup that also had to make enough power to set records.
Starting from just over 400 horsepower, Banks concluded that the engine's next major limitation was airflow. If the team wanted substantially more power, the intake side had to change. The stock intake manifold was removed so the intake ports could be reworked, and Banks began evaluating what could be done with the bolt pattern and head interface. That led to a modified head and the design of what he called the Big Hoss side-draft manifold, along with a fabricated exhaust manifold. With those changes, output climbed to nearly 540 horsepower.
When Banks reported the 540-horsepower result to Cummins engineering, the initial reaction was disbelief. Engineers knew fuel calibration had been increased and timing had changed, so they suspected development was continuing, but they did not believe the reported gain was possible. Banks answered by asking for another matching cylinder head so he could duplicate the work and send it back for verification. He repeated the side-draft conversion, extrude-honed the manifold, and completed the same package again. Cummins then tested it and saw the same 540-horsepower result. That confirmed the airflow improvements were real.
Even 540 horsepower was not enough for the ultimate goal, so Banks continued pushing for more air. By the end of development, the engine produced 735 horsepower at about 3,100 rpm. The team installed it in the truck with an automatic transmission and drove the vehicle to Bonneville. Once there, they unloaded the gears, wheels, and tires from the pit trailer, converted the truck into race trim, and Banks drove it to the starting line with a country radio station playing, underscoring that this was still a fully street-driven truck. Officials stopped him in the pits and told him he could not drive a race vehicle there, prompting Banks to point out that they had driven the truck to Bonneville in the first place. The truck broke the record on its first run. Because the record required a two-way average, the official best average became 217 mph, while the best one-way exit speed at the back door of the fifth mile was 222 mph.
The truck's usefulness did not end at Bonneville. After returning to Los Angeles, Banks refreshed the vehicle and then drove it on the Hot Rod Power Tour, which he recalled as being about 1,700 miles that year. The truck was driven to the event location, through the tour, and back home. After that, it was taken to Cummins, and over roughly a week it was shown at every major Cummins facility in the United States. The project demonstrated not only record-setting speed, but also the durability and practicality of the common-rail diesel package in a real street-driven vehicle.
Banks identified the engine on display as the original record engine from the 2001-2002 effort and described it as the world's first side-draft Cummins manifold for a B-series 5.9. He emphasized that Cummins did not fund the truck build itself; he undertook the project independently because of his enthusiasm for diesel performance. The truck is now in the NHRA Museum, while the engine remains at Banks. He then explained that he intends to revive the Big Hoss concept, this time specifically designed as a cast manifold for the 6.7-liter platform and priced to be affordable. Looking at the 2025 cylinder head, he said he was impressed by the intake ports and believes a side-draft layout can provide more uniform cylinder-to-cylinder boost-pressure distribution. His next step is to explore whether the new engine still has room for improvement, a process he plans to document in a video series titled Killing a Cummins.
