What do you do if you have a one-of-a-kind, highly advanced Class 8 research truck on your hands that you’ve already pushed diesel fuel boundaries with? You refit it with an advanced alternative-fuel internal combustion engine and see what it can do, of course.

That’s what Shell Lubricants and Cummins are doing with the Shell Starship test-bed Class 8 tractor-trailer. After making two successful, coast-to-coast, evaluation runs with a Cummins X-15 diesel engine, the Starship is being refitted with a new, Cummins X15N compressed natural gas engine.

Soon, the truck will once again be on America’s highways, giving Cummins and Shell engineers a first-hand look at the potential for this new engine and compressed natural gas as a long-haul fleet fuel.

Striving for Fuel Efficiency

If you missed the first two seasons of Shell Starship, don’t worry. The plotline is pretty easy to follow.

In 2017, Shell Lubricants engineers decided to explore what kind of freight efficiencies could be achieved with a highly advanced Class 8 tractor taking advantage of every viable transportation technology available.

The result was the Starship, a one-off design that took Class 8 tractor-trailer aerodynamics to the extreme. A major evaluation focus was on energy-efficient, advanced Shell lubricants, of course. Other technologies include rear-view camera systems, lightweight carbon-fiber body structures, an innovative, automatic fifth wheel gap extension, and a suite of advanced cruise control and safety systems.

The Starship 1.0 version hit the highway in 2018 on a coast-to-coast run from San Diego, to Jacksonville, Florida. On that inaugural run, the truck achieved 8.94 mpg. In 2021, after some tinkering, the truck repeated the run, this time achieving 10.8 mpg while carrying 18% more payload – 47,100 lbs. compared to 39,900 lbs.

The project grew out of one Shell had sponsored by former owner-operator Bob Silwa, whose first attempt at buildiing a more fuel-efficient truck landed his rig on the cover of HDT's November 1984 issue. Slwa's second project, the Bullet Truck (inspired by Japan’s “bullet trains") in the late 2000s was followed by the first iteration of the "Starship," which attracted sponsors like Shell in 2015.

Starship 3.0

Now, it’s time for Starship 3.0 to make the same run – but this time with compressed natural gas in its fuel tanks.

As with the first two Shell Starship runs, independent analysts from the North American Council for Freight Efficiency will be on hand to quantify the results of the drive.

“We learned what we could with Starship 1.0 and 2.0, and we’re applying those lessons now,” said Ryan Manthiri, project leader at Shell Global Solutions, the point man and lead engineer for Shell on the Starship.

“We’ve learned a lot so far and have really amazing results. Now, we are working in close association with Cummins to make sure all powertrain technologies on the truck are seamlessly integrated.”

Cummins Joins the Starship Team

Puneet Jhawar, general manager, global spark ignited business, is Manthiri’s Cummins counterpoint on the Starship project. He noted that although the first two version of the Starship featured Cummins power, there was no official collaboration between the two companies on the truck. But that has changed.

“We offered advice and insights, of course,” Jhawar said of the earler versions. “But we were not intimately involved.”

With the X15N compressed natural gas engine nearly in production, Jhawar said Cummins saw the Starship 3.0 as a perfect test bed to gain some early, critical data on the new engine and see first-hand how it performs in real-world operations.

“We only have approximately 15 X15N engines out trials now,” he said. “So, this will be a very early version of the engine and a golden opportunity for us to see how it performs.”

A new Eaton-Cummins automated transmission will replace the Starship’s original 18-speed experimental gearbox. And Cummins engineers will fine-tune the engine and transmission to a point that Jhawar said the powertrain performance characteristics will be virtually identical to that of a diesel engine.

Inside the Skunk Works

At a couple of secret “skunk works” facilities off the grid in rural North Carolina, the Shell Starship is currently in pieces as highly skilled fabrication teams rework the truck to set it up for its journeys as a CNG-powered truck.

In early September, HDT was among a select group of trucking journalists invited to see the ongoing work on the truck and learn more about its next mission.

At Reaper Customer Fabrications in King, North Carolina, owner Matt Greene and his technicians crawled over the Starship’s Navistar LT chassis, working to fit it with specialized Cummins CNG tanks and fuel system.

A few miles away, Greene’s old boss and mentor, Craig Tharpe, director of engineering and design at Spevco, a custom body-building shop with deep roots in Nascar, is refashioning the Starship’s cab design to adapt to the new fuel tanks and fuel system, tweaking a few other design points in the process. All-new Shell graphics are being added to the truck’s exterior, as well.

“Almost everything on this truck is custom-made,” Tharpe explained. “So introducing a new engine and fuel system requires a lot of changes to the body itself.”

Chief among these altercations are the Starship’s unique, side-mounted, retractable stairs allowing entry and exit to the cab. The stairs raise and rotate upward into the cab, much like the stairs on commuter jets do.

“With the removal of the exhaust aftertreatment system and addition of the compressed natural gas fuel lines and tanks, we needed to rework the stairs so they don’t interfere with those systems,” Tharpe explained. “This included reworking all the electronic control systems for the stairs, adding new safety proximity sensors, and adding a non-electric emergency system to deploy the stairs if power is unavailable.”

A New Fifth-Wheel Tractor-Trailer Gap System

Tharpe and his team also took the opportunity to completely revamp the Starships impressive — but temperamental — fifth wheel gap extension system, which Manthiri said never performed as well as hoped on the highway.

“At cruise speeds, the air pressure over the top of the cab forced the top panel down into the gap, actually creating significant drag,” he noted. “Moreover, the electric deployment and retraction system never worked as well as we wanted it to.”

Essentially, the entire fifth wheel system needed to be redesigned with more robust panels better able to withstand air pressures at highways speeds, as well as a simpler, but stronger and “smarter” deployment and retraction system.

He is extremely proud of the new system.

“It took a lot of thought and work to redo it,” he said. “The new system works better and deploys more reliably and in a way that ensures excellent air flow around and above the trailer gap.”

In just a few days, Greene and Tharp expect to have the new engine and fuel systems fully installed. They’ll spend a day reattaching the body to the chassis. And then a couple more days reattaching wires, piping, electrical connections as well as plumbing new ones.

Getting Ready for its Shakedown Cruise

Once those chores are complete, shakedown cruises will begin to troubleshoot any issues. And then serious evaluation runs will begin on various stretches of highway around the country.

“We are very interested in examining many issues with these trials,” Jhawar said. “We want to gain insight into comparative fuel economy and freight efficiency between diesel fuel and CNG. But we are also interested in demonstrating the range potential of this fuel in long-haul applications.”

Shell's goal is to have Starship 3.0 deliver a material demonstration of sustainable freight ton efficiency, using key performance metric, ton-miles of goods shifted per kilogram of CO2 emitted, Manthiri added.

The demonstration run will showcase how fleets can reduce their energy usage and emission profile, by using today’s readily available natural gas technologies and fueling infrastructures.

Another critical point Manthiri points to is fueling infrastructure. “Up to now, CNG has been limited to regional-haul applications,” he noted. “But we feel that it is important to showcase that the range of this truck, combined with growing CNG fueling infrastructure nationwide, will demonstrate that this fuel is a viable option for long-haul fleets.”

If all goes well, the Starship 3.0 CNG runs are slated to be underway by the end of September.