Inside Stainless Diesel’s New Pro Mod Corvette

Inside Stainless Diesel’s New Pro Mod Corvette

When you’re a three-time Pro Street champion with multiple record-setting passes under your belt, the next step in your racing career is pretty logical—you go even faster. For Stainless Diesel’s Johnny Gilbert, that meant bumping up to the Pro Mod category and building the quickest door-slammer he and his team possibly could. After scoring a proven 3-second performer—a ’63 split-window Corvette—as a roller in 2020, Johnny and his team mulled things over for several months before finalizing a game plan. The final decision? The second-generation ‘Vette would receive diesel propulsion by way of a Cummins and eventually run 3’s. The engine would be built by Wagler Competition Products, S&S would supply the fuel, MoTeC would control everything, the chassis would receive updates at Hammertech Racecars, and Rossler would get a call for one of its legendary Turbo 400s.of smiles.

So far, things are looking pretty good. At the car’s debut race, Outlaw Diesel Revenge in Indianapolis, Johnny, and the team walked away winners. Crazy enough, the goal that weekend only entailed making a few test hits to see how the chassis reacted. When the car responded with 1.15, 1.14, and then 1.07-second 60-foots, one thing led to another and the test session turned into a full-blown race. By Saturday night, Johnny found himself in the final round, and then the winner’s circle. Not a bad start for a car using roughly half of its 3,500hp potential.

All-Aluminum Cummins

After careful consideration, Wagler Competition Products’ CX400 Cummins got the nod for powering the car. The billet-aluminum block and head combination are completely void of coolant flow and, as expected, dissipates heat extremely well. In fact, it’s a challenge to keep heat in the engine at times. “The aluminum engine doesn’t get up to temperature as the cast-iron engine did, so it’s a learning curve,” Johnny explains. “We like to be at 800 degrees (EGT) minimum before I bring nitrous in, so we’re working with a 3-second spool-up time right now.” Thanks to locating the engine deep within the chassis, a 51-percent weight bias was achieved.

Cutting-Edge Common-Rail System

A top-feed style injector arrangement on the CX400 means there are no side feed tubes to worry about, and the injectors themselves are interesting pieces. They began life as Iveco-based units, chosen for their size (i.e. high-volume) and pressure capability (more than 36,000 psi), and through extensive modification at S&S Diesel Motorsport can easily support more than 3,000 hp. At optimum duration, they can flow 865 mm3 worth of fuel through their 6.7L-based 8-hole nozzles—but at the present time (and at roughly 1,800 hp) only 400 mm3 has been called upon. The wild common-rail injectors are supported by dual gear-driven S&S CP3s, both of which are high-speed 12mm stroker pumps. The driver-side CP3 accommodates an SP3000 mechanical lift pump, S&S’s bolt-on supply pump that’s capable of moving 3,000 LPH.

Big Single, Zoomies, Nitrous, And Water With Johnny’s company, Stainless Diesel, a major player in the turbo game, it only made sense that a charger of his own design made the cut. The in-house-modified GT55 sports a 98mm, 5-blade billet compressor wheel, a dual ball bearing center section, and hangs from a one-off, T6 polished Stainless Diesel exhaust manifold Johnny fabricated himself. The manifold also integrates the piping required to feed a pair of 45mm Turbosmart wastegates. The rest of the exhaust is perhaps the most captivating feature of the car: five 2.5-inch diameter zoomies. Void of an intercooler, intake temps and EGT are kept in check with a combination of nitrous and water, with the nitrous stages’ primary purposes being to shorten spool up while staging and adding horsepower down the track.

Applying Power With Proven Drivetrain Parts

Campaigning a TH400 (and a four-wheel drive version, no less) in Pro Street convinced Johnny and his team long ago that the proven three-speed transmission was the best path to going fast while also enjoying relative longevity. For Pro Mod, a Rossler-built TH400 sits behind the Cummins, and a Sun Coast 5-disc, bolt-together lockup converter handles power transfer. Once through the TH400, a carbon fiber driveshaft routes power to a Pro Mod 9-inch rear end and ultimately a pair of 36-inch Hoosiers. A fine-tunable four-link from Tim McAmis Performance Parts aids the power-planting effort, while Strange Engineering carbon brakes all the way around help bring the car to halt after the parachutes have been deployed.

The Road To The 3’s (Has Begun)

In a previous life, the split-window Corvette went 3’s as a big-block nitrous car—so it’s no wonder Johnny is convinced it can do it again, only this time under diesel propulsion. With a past that saw him campaign a 4,400-pound 4×4 truck in a reliable, 4.8-second fashion, there is no reason to doubt his current, 3-second, 200-plus mph ambitions. How long it will take to get there remains to be seen, but don’t be surprised if—just as he did with his Pro Street program—Johnny begins to gradually chip away at his goal and eventually ends up going rounds in the 3’s. Like other diesel racers that put the Pro Mod world on notice, Johnny plans to further help put oil-burners on the map among the fastest door slammers in existence. In his own words: “We’re ready to give them a run for their money in a diesel.”