Wheels-Up, Cummins-Swapped, '75 Square Body C10

• August 17, 2021
• Story By
  Mike McGlothlin

Not many gearheads can say they commute to work in their 9-second play toy—and they’ve probably never met Jesse Harris, either. The Indiana native’s ‘75 Chevrolet C10 turns heads wherever it goes, usually for the wheels-up launches and elapsed times it posts at the drag strip or for the fact that there’s not a traditional big-block Chevy exhaust note leaving the tailpipe. It’s Cummins-powered, compound turbocharged and 48RE-shifted. But that’s not all. Having been in the family since new, and in Jesse’s possession since 1992, it’s got a lot of history behind it. It’s been stolen, recovered, wrecked, rebuilt, made the rounds of Hot Rod Drag Week, sees regular track time, is daily driven and even tows a trailer.

“The truck was never intended to be a street vehicle,” Jesse tells us. “But when we put the diesel in it it drove so nicely I couldn’t help but drive it everywhere...Plus, I get 24-mpg out of the Cummins.” And (once again) that’s not all. Jesse also reports he puts more than 15,000 miles a year on the truck—and that drag slicks last a lot longer on the street than most people give them credit for… Join us below for a closer look at his one-of-a-kind anomaly.

Hard-Hitting & Well-Oiled

If you’ve been to Hot Rod Drag Week or Rocky Mountain Race Week in recent years, you know about this Scottsdale trim C10. Behind the wheel since 1992 (though not always diesel-powered), Jesse Harris has made thousands of passes in his square body Chevy and typically sends it down the track some 400 times a year. Experience in the driver seat, combined with the perfect amount of slip from the big slicks out back, produces repeat wheels-up performances—and 1.0-second 60-foots. That’s 3,000hp diesel dragster and Pro Mod territory on the hit… “I like to leave at 50-psi of boost,” Jesse says. “Leaving at 25-psi, it dead hooks and wheelies like crazy—and that’s when you can break stuff.” Not bad for an old farm truck.

Common-Rail Cummins

Because he’s been into drag racing diesels since the turn of the century, Jesse had no issue slamming a Cummins into his square body. Initially however, the power plant was a P-pumped 24-valve 5.9L, but a recent switch to an electronically-controlled, common-rail 6.7L has brought with it improved consistency and superior power management. Complete control over the injection system and access to the ECM via EFI Live provides for unmatched tunability. As for the Cummins’ hard-parts, its internals are bone-stock. Even more impressive, Jesse believes the truck sends more than 1,200hp to the rear wheels.

Quick-Lighting, Small(ish) Compounds

Robbed from a Ford/Cummins (Fummins) swap, Jesse’s compound turbo arrangement is a bit undersized by today’s diesel standards, but that doesn’t mean it doesn’t work. In fact, the quick-spooling nature of his S300/S400 setup is part of the reason for the truck’s nasty, wheels-up launches (as well as the aforementioned 1.0-second 60-foots). At the same time, the combination of chargers doesn’t seem to run out of air on the big end. Peak boost checks in between 70 and 72 psi on what we’d call a very mild tune-up (in diesel speak: only 1,100 microseconds of injector duration is being commanded).

Overkill Fuel System

Adequate rail pressure being maintained for a set of very large injectors to use is a recipe that’s proven to be the secret sauce for common-rail diesels over the years—and that’s exactly the path Jesse has pursued. A 14mm CP3 from S&S Diesel Motorsport (a pump capable of supporting 1,400 hp on fuel alone) feeds high-pressure fuel to a set of S&S injectors that’ve been topped off with 300-percent over nozzles. Low-pressure fuel supply begins with a 10-gallon cell (mounted rearward of the Moser 9-inch) and a pair of Aeromotive A1000 pumps. An Aeromotive bypass regulator provides for 14-15 psi of supply pressure at idle.

Tube Chassis And The Rest Of The Powertrain

Once upon a time, Jesse’s C10 was a stock frame, long-bed, but in the aftermath of an accident that nearly totaled the truck Jesse decided to do much more than simply bring it back to life. A tube chassis frame was built, along with a roll cage that’s certified for 8.50s in the quarter-mile. A four-link rear suspension with CalTracs, Mustang II spindles up front and coil overs all the way around make for a race-ready chassis that also rides well enough on the street for Jesse to rack up more than 15,000 enjoyable miles a year. A Moser 9-inch with a 3.00 ring and pinion and a homebuilt 48RE that’s chock full of Goerend parts (including a torque converter dump valve) cope with everything the Cummins sends their way.

Wrecked. Then Reborn.

It’s hard to look at, but this is the wreckage that triggered the full-race rebuild and ultimately what brought the truck to its current level. The body was fixed (and all that that entails…) and the original two-tone paint scheme was retained—as was all-steel sheet metal. That’s right, the bed, doors, cab and hood are all steel, and there is also no Lexan to speak of. The only bits of fiberglass on the entire truck are the front and rear bumper, and its overall weight reflects that. Without Jesse in the driver seat, his short bed C10 tips the scales at 4,181 pounds.

Mid 9’s, And Much More To Come

The photo above is a few years old, but depicts Jesse’s quickest quarter-mile pass to date in the truck. During this trip through the 1320—and after having seen 138-psi of boost—the P-pumped 24-valve Cummins’ block checked out, cracking at the cam line and freeze plugs. Shortly after, the idea of going common-rail surfaced and the rest is history. Although Jesse hasn’t made a clean pass through the quarter-mile yet on the common-rail engine, he has been 5.61 at 120 mph and change in the eighth-mile. To anyone in the know, this means low 9’s or even high 8’s should be on the table. Of course, the truck’s dramatic, violent launches and attention-grabbing wheelies remain the truck’s headlining act. Trust us, it turns heads at every track it visits.