The World’s Fastest Pro Street Diesel Truck

• August 22, 2020
• Story By
  Mike McGlothlin

It may still be considered a niche motorsport, but diesel drag racing is definitely a thing. And for the competitors that live and breathe it, it’s a very serious thing. For the past few years, Johnny Gilbert and his team at Stainless Diesel have been campaigning a second-gen Dodge Ram at the top of the Pro Street diesel class—and their 2,500-plus horsepower, Cummins-propelled beast just set a new eighth-mile record. After stringing together a host of low 5-second passes in the 150-mph range, Johnny drove the truck to a 4.92 at 155.7-mph, effectively obliterating the old trap speed record in the process.

For the sake of comparison, just 10 years ago Pro Street diesel trucks were barely knocking on the door of high 5’s in the eighth-mile and trap speeds rarely exceeded 120 mph. So what’s changed? For starters, horsepower has more than doubled, power management is much more precise, transmission options have improved and common-rail injection technology has come to dominate. Employing all of the above, Johnny and the Stainless Diesel team are flying high in 2020—with plenty of racing still to come. To get a sense of just how impressive this Pro Street machine and the crew behind it is, keep scrolling.

Pro Street Diesel Trap Speed Record: 155.7 MPH

It’s been a long time coming for Johnny Gilbert and the Stainless Diesel crew. After knocking on the door of 150-mph for a while (and flirting with 4-second territory for an even longer period), Johnny finally broke through on the trap speed front in early July. And just two weeks after obtaining that new personal best trap speed of 150.26 mph, he and his team took advantage of cooler track conditions and threw a more aggressive tune-up at the common-rail Cummins. The truck responded by dead-hooking, grabbing a 1.25-second 60-foot and sending its 4,500-pound heft through the ‘660 in 4.92 seconds at a record 155.7 mph.

A Group Effort

Although more than 2,300 hp made it to the slicks on the 155.7-mph pass (according to the calculators available at WallaceRacing.com), there is definitely more to setting records than simply making gobs of horsepower. You have to maintain traction, apply your power with precision and keep the engine from exploding in the process. Putting together a record-setting pass is always the result of a full team effort. Thanks to the use of a stand-alone Bosch Motorsport ECM, things like ground speed, shock travel, EGT and dozens of other key parameters are logged each time the truck makes a pass. The guys under the Stainless canopy even measure G-force and yaw, too (and we’ll note that hard launches can yield as much as 2.2 G’s).

4x4 TH400

A big part of Stainless Diesel’s success is a direct result of switching to a TH400 with a trans-brake. Similar to what goes into the Pro Mod cars you see, but four-wheel drive in this application, the Turbo 400 has been much more durable than the previous 48RE platform was for the Stainless Diesel guys. The TH400 program got underway with the help of Wilson Patterson Diesel roughly two years ago and makes use of a bolt together, 5-disc Sun Coast converter. The converter’s serviceable design allows for end-user stator and clutch stack changes to be made. Within the transmission case, sprag issues seem to be the biggest issues the 2,500hp combination faces and Johnny tells us they’ve yet to hurt a clutch pack. Compare that from a few years ago, when breaking 48RE transmission cases was an everyday (and very time-consuming) occurrence.

Less Breakage Means More Seat Time

Johnny and team aren’t alone in campaigning a TH400 in diesel drag racing. In fact many Pro Mod as well as Pro Street teams have made the switch in recent years in search of better reliability. Now, with many of the TH400’s minor issues ironed out and plenty of seat time with it, Johnny and team are beginning to realize the time-tested Turbo 400 will take virtually everything they can throw at it. “We’ve always had the power to put through it,” he told us. “It was just a matter of making it play well with the chassis.”

The Struggle In Applying 2,300+ HP

This is the type of tire wrinkle you get when you’re launching a 4,500-pound truck with 30-psi of boost on tap, but make no mistake about how easy the Stainless truck makes its mid 1.2-second 60-foots appear. According to Johnny, “we actually hit the 60-foot hard, then pull out horsepower, then pour it back on, so a lot of trickiness happens around the 60-foot mark.” He also tells us the team still has another 500hp available, but it’s such a fine balance in using it (without losing traction) that every single pony has to be finessed and applied at the right time.

Track Conditions Matter

Even in the midst of low 5-second blasts it’s sometimes necessary for Johnny to lift. Case in point, at a race on a hot, greasy track back in July, one data log revealed that he backed out of the throttle 20-percent after the converter locked and caused the truck to momentarily break traction. Recovering almost instantly, he still went 5.06 on that pass… When track conditions were 50-degrees cooler and traction was constant, Johnny pulled off the record, 155.7-mph pass that made him the fastest Pro Street diesel driver on the planet.

Single Turbo & Nitrous: A Simplified Path To Big Power

Under the fiberglass front clip, you’ll find a sleeved and deck-plated 6.7L-based Cummins built by Pine Hill Auto LLC in Carrollton, Ohio. D&J Precision Machine rods and Diamond pistons are part of the rotating assembly, a Wagler Competition Products head sits up top and S&S Diesel Motorsport provides plenty of fuel thanks to stroker CP3’s and agriculture-based 6.7L injectors. The single turbo is the biggest news for 2020, with Johnny and team scrapping the triple-turbo arrangement the truck sported for years in favor of a sizeable, 88mm Garrett GT55 with a 4-inch turbine wheel. By switching to the single, 100 pounds was shaved off of the truck’s bottom line and the power that was sacrificed is made back up with the use of nitrous (6 to 8 pounds worth per pass).

Team Stainless

As diesel drag racing continues to evolve and further establish itself as a true, semi-professional entity, you’ll find a lot more than simply a driver and one of his or her friends in the pits. Thanks to a rock-solid mix of family and friends, the team behind Stainless Diesel’s record-setting trap speed, its 2019 ODSS Pro Street points championship and its runner-up finish in 2018 have been instrumental in all of the recent successes. Driver Johnny Gilbert (center)—always cool, calm and collected—is noticeably comfortable behind the wheel. John Gilbert III (second from left) handles the ECM tuning and friend Stephen O’Neal (far left) is in charge of the truck’s nitrous system. Johnny and team are currently second place in the ODSS points chase this season, but given their consistency and recent accolades we expect them to repeat in 2020.