Salty Box Racing: A Father-and-Son Legacy Reaches 328 MPH
For Tim Boyle and his son Ryan, speed has never been just about a number on a timing slip.
For years, the father-and-son team behind Salty Box Racing has been pushing the limits of diesel performance across the Bonneville Salt Flats, steadily building a reputation for doing things that conventional wisdom says a diesel shouldn’t do.
This year, that family legacy reached another incredible milestone.
Ryan Boyle piloted the Salty Box Racing “Thunder in the Morning” diesel streamliner to a new C/DS land speed record of 328 MPH.
The accomplishment is the latest chapter in a story that includes multiple records, years of development, and a team that has continually found new ways to make diesel power go faster.
And 328 MPH wasn’t the only record-setting performance from Salty Box Racing this year.
From a Diesel Pickup to a 300+ MPH Streamliner
Salty Box Racing started in 2005 when team owner Tim Boyle brought a modified 1931 Ford Model A sedan to the Bonneville Salt Flats. That original hot rod sedan—nicknamed the “Salty Box”—ran on blown alcohol and set multiple class records, laying the groundwork for the team’s future evolution into extreme diesel land speed racing.
The team’s early efforts centered around a 2008 Dodge Ram 2500 known as “Sooty.” What started as a salvage-title street truck evolved into a serious Bonneville land speed machine. Garrett Motion documented the progression of Sooty from its early 166 MPH run in 2012 to a truck producing more than 1,200 horsepower and setting records at more than 230 MPH.
Read the Garrett Motion feature on “Sooty”
That early success helped establish the foundation for what would become an even more ambitious project: the purpose-built “Thunder in the Morning” streamliner.
In late 2019, Salty Box Racing purchased the streamliner, originally constructed by longtime land speed racer “Fast Freddie” Dannenfelzer. The team began converting it to Cummins diesel power and developing the combination specifically for extreme-speed land speed racing.
Read Garrett Motion’s feature on “Thunder in the Morning”
The early streamliner combination centered around a 5.9L Cummins, compound Garrett turbochargers and an extensively modified 48RE transmission. At the 2021 SCTA World Finals, the car recorded an official average of 314.73 MPH, with a GPS peak of 321 MPH.
That was the moment the streamliner announced that it was capable of running with the fastest vehicles on the salt.
Tim Boyle: 315 MPH
At Speed Week in 2024, Tim Boyle drove “Thunder in the Morning” to a new 315 MPH C/DS record.
The qualifying run reached 318 MPH, followed by a 312 MPH backup run, establishing the 315 MPH record. GPS data showed the streamliner reaching a peak of approximately 324 MPH.
Read Garrett Motion’s 2024 coverage of the 315 MPH record
The 2024 effort was particularly significant because it represented years of development coming together. Garrett Motion’s coverage detailed the 30-foot streamliner, its 5.9L Cummins, compound Garrett turbo system and the manually shifted Stage 4 48RE transmission transferring power to the custom rear differential.
The record also continued Tim Boyle’s long history at Bonneville.
But the next record would belong to his son.
Ryan Boyle Takes It to 328 MPH
At this year’s Bonneville event, Ryan Boyle piloted “Thunder in the Morning” to a new C/DS record of 328 MPH with an exit speed of 333 MPH.
For Ryan, this isn’t his first time in the Bonneville record books.
He previously set a 227.870 MPH B/DT record in 2018, earning his place among the Bonneville 200 MPH Club record holders.
That makes the progression particularly impressive.
Ryan went from a 227 MPH diesel pickup record to taking the wheel of a purpose-built streamliner and pushing the same family program beyond 328 MPH.
This isn’t simply a new record for Ryan.
It’s the continuation of a program he has been part of for years.
The Power Behind the Record
At the heart of the current combination is a 5.9L CommonRail Cummins diesel, tuned by Hardway Performance, and currently producing approximately 2,000 horsepower.
The engine combination has evolved considerably since the streamliner’s early days. Garrett Motion’s original feature on the car documented a 5.9L Cummins paired with compound Garrett turbochargers, with Hardway Performance’s Ryan Milliken managing the tune.
By 2024, the combination had evolved again, with Garrett Motion reporting a 5.9L Cummins featuring a Hamilton cam, D&J Precision cylinder head, S&S Diesel fuel-system components and a pair of Garrett turbos.
Read the Garrett Motion technical overview of the streamliner
All that power ultimately has to make its way through the drivetrain.
That’s where our Stage 4 48RE transmission comes into the story.
The transmission in “Thunder in the Morning” is a manually shifted Randy’s Stage 4 48RE, built to handle the demands of the streamliner and transfer power to its custom rear-end assembly.
For Randy, this project was one of his earlier ventures into the high-performance side of the business. Those early experiences in 2019 at the Tooele shop helped lay the groundwork for the high-performance diesel work during the years that followed.
At roughly 2,000 horsepower and more than 300 MPH, the transmission has an enormous job.
It’s not enough to make power.
You have to reliably put that power to the ground.
That’s what makes being part of a project like Salty Box Racing so meaningful to us. Our Stage 4 48RE is operating in one of the most extreme diesel applications imaginable.
Then They Took Away a Cylinder
But Ryan’s 328 MPH record wasn’t the only impressive run Salty Box Racing made this year.
The team also entered the D/DS class, with crew member Rob Murphy taking the wheel of the streamliner.
And they decided to do something a little unconventional.
The team disabled injector number six, intentionally allowing the 5.9L Cummins to run on only five cylinders.
Then they went after the record.
Rob piloted the now five-cylinder streamliner to 218 MPH, beating the previous record in the D/DS class.
Think about that for a moment.
A 5.9L Cummins running on five cylinders, powering the streamliner down the Bonneville salt—and still going 218 MPH.
It’s a perfect example of the kind of ingenuity that has defined Salty Box Racing from the beginning.
The team didn’t simply chase maximum horsepower. They adapted the combination for another class, took a different approach and found a way to put the available power to work.
Five cylinders. 218 MPH. Another record.
Rob Murphy’s run adds another impressive chapter to what was already an extraordinary Bonneville campaign.
A History of Pushing Diesel Limits
Looking back at Salty Box Racing’s history, the 328 MPH record doesn’t seem like an isolated achievement.
It’s the result of years of incremental progress.
The team’s earlier diesel truck program evolved from a street-driven Dodge Ram into a 230-plus-MPH land speed truck. Garrett Motion’s coverage of “Sooty” documents Tim Boyle and the team developing the truck through progressively more serious engine, turbocharger, chassis and safety modifications.
Read the full “Sooty” story from Garrett Motion
The streamliner then took the program into another category of speed.
In 2021, “Thunder in the Morning” recorded a 314.73 MPH official average at the SCTA World Finals.
Three years later, Tim Boyle pushed the official C/DS record to 315 MPH at Speed Week 2024.
Now Ryan has taken that number to 328 MPH.
The progression is remarkable.
Tim Boyle
- Early Bonneville records with Salty Box Racing’s diesel truck program
- 230+ MPH Sooty land speed records
- 315 MPH C/DS record — 2024
Ryan Boyle
- 227.870 MPH B/DT record — 2018
- 328 MPH C/DS record — 2026
Rob Murphy
- 218 MPH D/DS record — 2026, running the Streamliner 5.9L Cummins on five cylinders
A Family Legacy at 328 MPH
There’s something especially fitting about Ryan being the one to set this latest record.
Tim Boyle helped establish the foundation. He and the Salty Box Racing team spent years developing the vehicles, powertrain and knowledge necessary to compete at the highest levels of diesel land speed racing.
Ryan grew up around that program and eventually became a record holder himself.
Now he’s taken the family’s streamliner to 328 MPH.
And alongside him is a crew that continues to find new ways to make the combination work—including Rob Murphy’s remarkable five-cylinder, 218 MPH record run.
For us, being part of that story with our Stage 4 48RE is something we’re incredibly proud of.
328 MPH.
A new record for Ryan.
Another milestone for Tim.
Five cylinders and another record for Rob.
And another chapter in the Salty Box Racing legacy.
There’s already talk about more power and possibly even nitrous for next year, but who knows.
Congratulations to Tim Boyle, Ryan Boyle, Rob Murphy and the entire Salty Box Racing team on an incredible new record. We’re proud to be part of the combination and can’t wait to see what comes next.