The 12-Valve Terror: Steve Driscoll’s Vision Of The Perfect 2nd-Gen Cummins

It’s been said that the 12-valve Cummins diesel engine is perhaps the greatest diesel engine ever invented. Initially put into service in three variants in 1984, as the 6B, 6BT (turbocharged), and 6BTA (turbocharged and aftercooled), the 5.9-liter powerhouse was installed in many heavy-duty applications all over the world, like tractors, combines, road graders, and even school buses. When Dodge selected the Cummins Turbodiesel in 1989 as the powerplant for its 2500 and 3500 pickup trucks, a star was born. And when Steve Driscoll drove a friend’s truck several years ago, he was immediately hooked on the idea of huge power in a truck that could be driven every day.

“I built this truck for the simple power and longevity of the 12-Valve mechanical motor,” he says.

“The build has taken over seven years to get the truck to where it is now. It was a daily driver for five years of those seven, and in the last two years, I have been rebuilding the motor, transmission, and drivetrain to hold a reliable 1,000 horsepower, in a streetable truck, without compromising drivability.”

Thus began the long and tedious path to take what was formerly a green work truck into the charcoal grey tire-shredding monster seen in these photos. Side note—thanks to Steve for getting up well before the sun to meet us in a local park to take advantage of the surroundings.

The 12-valve is nearly indestructible in factory form, and Driscoll has invested substantial effort into beefing it up even further through collaboration with many of the diesel performance industry’s heavy hitters.

After kissing a piston with a valve in the stock engine, Driscoll enlisted the help of UCF Machine in Carlisle, PA to machine the ’97 block .020-inch oversize and get it ready for big power. The decision was made to outfit it with one of Haisley Machine’s crankshafts, a Gorilla Girdle underneath, a set of Carrillo connecting rods, and Mahle pistons with stock bowls.

The guys at D&J Precision Machine—also responsible for the insane engine in Lavon Miller’s Firepunk Diesel Ultimate Callout Challenge truck—machined and ported the cylinder head to get it ready for big boost from the pair of BorgWarner turbochargers arranged in a compound configuration. A fire ring setup was machined into the head and block surfaces to ensure no boost could escape the cylinders, and ARP Custom Age 625+ head studs are used to keep the compression in the cylinders. A Stage 3 Hamilton camshaft, Haisley Machine pushrods, and Haisley heavy-duty valve springs ensure that the valves open and close as necessary. One of Power Driven Diesel’s timing gear setups is also in place.

Once the engine was sorted out, it was delivered to Corey Virnelson at Virnelson Diesel Services, which is located just a hop, skip, and jump away from Driscoll’s Red Hill, PA home base. Corey and the VDS team were tasked with assembling the rest of the truck; plenty of fabrication was required at this step of the build, not least of which included the turbo system components. Vibrant Performance’s HD clamp assemblies and a full complement of aluminum tubing were chosen to make the system complete.

Sourced from Power Driven Diesel, the small BorgWarner S362SX-E 62mm turbocharger feeds into the S480SX-E large turbocharger to help this engine make tons of boost when Driscoll asks for it. But as the 12-valve uses the mechanical fuel injection system—which is timed off the camshaft, and is one of the reasons that the engine is so dead-simple and reliable—he made some accommodations to control the turbo system’s performance.

“I also run a Turbo Tuner from Power Driven Diesel, this allows control of turbo spool on the small charger, along with an AFC Live which allows you to turn the fuel back for daily driving and allows you to tune the mechanical motor on the fly,” he says.

The Stage 4 215HP P7100 injection pump has been modified by Farrell Diesel Service in Kansas City, and works in conjunction with Dynomite Diesel Products injectors and a FASS Fuel Systems 220 lift pump.

At the time we shot these photos, he was running an intercooler that has since found its way to the aluminum recycling plant due to a “too much boost” situation—read that as north of 85 psi—so VDS has installed a brand-new Mishimoto intercooler to ensure the air pressure stays inside.

The AFC Live in-cab tuner allows him to control the fuel rate adjustment, the maximum fuel adjustment, and offers complete EGT control as well. Other notable additions include the Flex-A-Lite dual electric fan setup, the Steed Speed manifold, Banks dual intake, and one-piece billet aluminum Keating Machine valve cover, timing cover, and tappet cover.

Firepunk Diesel’s Comp 2 transmission benefits from billet input, intermediate, and output shafts, a Firepunk 48RE valvebody, and a Suncoast triple-disk torque converter. A double-deep ATS transmission pan and BD Diesel double-stacked transmission cooler keep the fluid temperatures in check.

The suspension is tuned up with Bilstein 5100-series shocks, a BD adjustable track bar, and a long-arm kit from Tuff Country for the front of the truck. In the rear, Virnelson designed a set of custom traction bars in-house to help the truck plant all of the power to the road. Gearing was changed from the stock 4.11:1 ratio to a power-friendly 3.55:1 ratio to help keep the truck in its powerband more effectively.

No expense was spared when it came to sorting out the appearance and creature comforts, either. Steve Driscoll has put his fingerprint on every aspect of this build. SG PaintWorx of Lansdale, PA, helped to change the truck’s appearance from its former green exterior hue into what it is today.

“We had the complete truck disassembled and reassembled. We accented the truck with a very durable Rhino Liner on the complete underside of the truck, and all of the interior flooring behind the interior panels were coated as well, along with accents on the exterior like the mirrors, door handles, roof, and bumpers This gave the truck a very quiet interior, from the deadening application of the Rhino Liner. We also put DynaMat on the inside of the doors and remainder of the interior behind the panels. This is to prevent road noise and engine noise, so I can hear the sound of that sweet turbo Cummins motor,” says Driscoll.

The muffler-delete 5-inch exhaust from aFe Power allows him to do just that. I can tell you from personal experience that this truck delivers upon its promise. Corey Virnelson and his team at VDS have assembled a serious truck which gives its owner exactly what he wanted.

“It makes in the range of 800 to 1,000 horsepower, depending if I change the current air setup/fuel setup to get more power. At the moment it is an extremely fast, fun, and reliable street truck, with the capability of holding much more power,” says Driscoll.

We figure it’s only a matter of time until he turns it up again.