It’s almost like we planned to close out this series with a bang. For Part 6, we’ve got three ultra-fast Cummins swaps and a record-setting, Allison-shifted, Duramax-powered Chevrolet Silverado to show you. They compete in the growing 5.90-second eighth-mile Index class within the Outlaw Diesel Super Series, but each of them has the ability to rocket much deeper into the 5’s. Below, you’ll find that one 5.90 racer has run high 8’s in the quarter-mile and that another will regularly compete at radial tire events—where he will likely end up going deep into the 4’s. Two candidates are also well under 4,000 pounds while another is nearly 6,000—yet they all come together to run the 5.90 category on race day. It’s no wonder this fast, diverse and super-competitive class has become the talk of diesel drag racing.
Justin Duffy’s Record-Setting Bow-Tie
After running 6.70 Index last year, Justin Duffy decided to step up to 5.90 Index in 2021—and we’re glad he did. His ¾-ton Silverado recently ran a 5.86-second eighth-mile at 124 mph, making it the quickest 4x4 Allison truck in the world. Even better yet, Justin had this to say: “We’re going for 5.70s or better on the Allison before I swap to the 48RE Chris Gelbaugh is currently building for me.” Despite the employment of GTS fiberglass bed sides and other efforts to strip weight, Justin’s Chevy still tips the scales at a hefty 5,800 pounds. He calls the truck “Fat Amy.”
Big Single And Highly-Fueled
Although he was able to get away with running a stock 6.6L in the 6.70 Index category, bumping up to 5.90 required a full-on engine build. The short-block was built by Marty Brown and an HSP Diesel piping kit accommodates the big single S400 turbo parked in the valley. The sizable snail is externally wastegated to keep drive pressure in check when the nitrous kits are activated. S&S Diesel Motorsport provided a fuel system that consists of 400-percent over injectors, a 14mm stroker CP3 in the factory location and a 10mm CP3 driven off the serpentine belt. The record-setting Allison transmission was pieced together by Diesels Unlimited and sports a Goerend Transmission converter. The truck is tuned by Blake Crenshaw.
Robert Berry’s ’45 Chevy Rat-Rod
No, it’s not just another diesel rat-rod. This thing moves! Robert Berry’s 1,300rwhp ’45 Chevy wears its original bed, fenders and cab, along with sitting on a full frame and not a tube chassis. That said—and even with a 1,000-pound Cummins up front consuming the engine bay—his rat-rod weighs just over 3,700 pounds on race day. This means Robert’s horsepower-to-weight ratio is perfect for allowing parts to live while still being lightning fast. After being unable to qualify at the Outlaw Diesel Revenge event in Indianapolis, Robert spent some time testing and working on his launches. Now, “Burnie” (as he calls it) can cut low 1.4-second 60-foots and recently went 8.93 in the quarter-mile. That means 5.70s (if not 5.60s) are possible in the eighth. Long story short, now that Robert is getting the old Chevy dialed in, running consistent 5.90s should be coming.
5.9 Liters Of Fury
Robert’s Chevy started out under P-pumped Cummins power, but was converted to electronic controls and common-rail injection in order to make going fast much easier. His 5.9L common-rail was obtained through Industrial Injection’s Tyler Kipp and makes use of a balanced crank secured via Gorilla girdle and ARP main studs, swings Carrillo rods, features a stage 2 fire-ringed Industrial head and utilizes a Hamilton cam. A set of 450-percent over injectors are supported by dual 12mm CP3’s and twin FASS low-pressure supply systems. Compound turbos cram plenty of boost into a vertically-mounted intercooler before the cooler intake air enters a Banks Big Hoss manifold. On a conservative tune-up, Robert’s rat-rod made 1,283rwhp on Firepunk Diesel’s chassis dyno.
Travis Trent’s Cummins-Swapped, Short-Bed Ford
Travis Trent’s short-bed Ford has been on the diesel drag racing scene for several years now, and it’s only gotten faster each season. He has competed in the UCC Qualifier in the past, stepped up to 5.90 Index for 2021 and rumor has it that you’ll be able to catch Travis at King of the Street this fall. His ’05 F-250 was back-halved by API Fabrication and Repair, the shop that also performed all of the truck’s fabrication work, while Diesel Conversion Specialists supplied the motor mounts, alternator mount, transmission adapter plate and flex plate to make both the 6.7L Cummins and the 4R100 transmission work.
A Proven Recipe: Common-Rail Cummins + Big Single
Under the hood, you’ll find a work of art—and a built-for-battle 6.7L Cummins that’s been fitted with a deck-plate. Travis also kept things simple by going the big single turbo route. His charger of choice is Stainless Diesel’s 5-blade S485 Godfather, which mounts to a Stainless exhaust manifold with two 45mm TurboSmart external wastegates. S&S Diesel Motorsport supplied the massive 500-percent over common-rail injectors while the Exergy 12mm CP3 on the gear is aided in producing rail pressure by a stock Bosch CP3 driven off the belt. A Sam Wyse (of Wyse Auto Repair) 4R100 automatic with a Goerend converter ensures the Cummins’ power gets to the ground efficiently and reliably.
Ryan Milliken’s Stunning, Cummins-Powered ’69 Nova
You’re more likely to find this beautiful ’69 Nova graced with radials and going head-to-head with gassers at events like No Mercy and Lights Out, but Ryan Milliken’s Glacier Blue Nova did hit the ODSS circuit with good friend, Jonathan Montesino behind the wheel. It boasts a dry, filled block 5.9L Cummins built by Freedom Racing Engines and fitted with a Peterson dry sump oil system. A Wagler Competition Products’ billet dual CP3 cover provides a home for dual 14mm CP3 pumps from S&S Diesel Motorsport. The reverse rotation pumps keep ample rail pressure on tap for a set of 6.7L Cummins-based S&S injectors equipped with 400-percent over nozzles. An 85mm GT55 (GTX5533R), nitrous, a MoTec stand-alone ECM and a Sun Coast TH400 are also onboard.
Select photography provided courtesy of Amy Gilbert from Stainless Diesel