Colton Rhodes’ 1,000HP L5P Breaks All The Rules
Big single, CP3 conversion, sizeable nozzles, and a bone-stock long-block…what could go wrong? Welcome to Colton Rhodes’ world. The 20-something Missourian is redefining what it means to push the limit—and he’s doing it every time he cycles the ignition of his ’17 Silverado. The L5P Duramax under the hood has gone completely untouched despite receiving a host of fuel and air upgrades—and the built-to-the-hilt Allison behind it means the transmission is never going to be a weak link. His reasoning for the apparent death wish for the engine is simple: if you don’t push the limits, you’ll never know how much you can get away with. Plus, when you “know a guy” with a machine shop, it doesn’t exactly act as a throttle stop.
Stock As A Rock
Did GM’s new casting and additional heat-treating processes truly improve the strength of the L5P’s gray-iron block? Will the 20-percent larger rod bearings really help them live at higher horsepower? And can the thicker walled pistons it’s said to have survive the cylinder pressure that comes with 1,500 lb-ft of torque? Colton will get back to you on that, but so far so good. The seal has yet to be broken on his 110,000-mile Duramax, and he doesn’t plan to pull the valve covers until something gets hurt. Not even the head bolts have been swapped in favor of ARP studs at this point. It’s simply been full speed ahead.
The Denso HP4 and factory in-tank lift pump are the latest and greatest in fueling, making for solid potential right out of the box on the L5P, but there was no way they were going to support the kind of power Colton sought after. A CP3 conversion from S&S Diesel Motorsport allowed one of S&S’s 12mm pumps to replace the HP4 in the factory location. For low-pressure fuel supply, a Titanium Signature series FASS system was added, and its 220-gph flow rating ensures the CP3 will never run dry. The factory solenoid style Denso injectors were pulled and sent to S&S for 150-percent over nozzles and a few of the company’s in-house modifications.
An S472 With Manners
Despite Colton having no reservations about pushing the stock bottom end to the brink, there is no denying that a single turbo—and a fixed geometry unit at that—is much easier on hard-parts than compounds, or even a large VGT. Armed with this common knowledge, he decided to run an S472, which was made possible thanks to HSP Diesel’s S400 single turbo install kit. But instead of having a power curve that comes on like a light switch, the big single was sourced from Stainless Diesel, a turbo manufacturer that’s known to build some of the most drivable S400’s in the industry. At Stainless Diesel, the S472 was treated to the company’s 5-blade billet compressor wheel, an 87mm turbine wheel, and also fitted with a 1.0 A/R exhaust housing.
Built Allison and Traction Upgrades
As expected, the Allison was one of the first components to benefit from upgrades. For a full-on, competition-ready build, LinCo Diesel Performance got the call. In its care, the six-speed was fitted with Sun Coast-sourced billet input, intermediate, and output shafts, Sun Coast’s P2 planetary and billet C2 hub, and LinCo’s proprietary clutch packs. A high stall (2,800 to 3,000-rpm), 1071 Sun Coast triple-disc torque converter helps bring the S472 to life quickly, and a deep pan from PPE adds four quarts of fluid capacity. With the Allison ready to handle anything the L5P could dish out, Colton added Kryptonite tie-rod sleeves before attempting the first four-wheel drive launch—along with adding a set of LinCo’s bolt-on traction bars to eliminate rear axle wrap.
As Colton continues to work with the experts at CTT Tuning to dial everything in electronically, he’s been racking up plenty of miles (many of which are hard-earned) on the new setup. Should any engine issues arise, the L5P will be treated to a SoCal cam and ported heads, along with ARP head studs, during a rebuild. Whether the engine remains completely stock or sees a complete race-ready overhaul between now and summer, he plans to visit the drag strip and even hook to the sled a few times once the weather warms up. Call it fearless, call it cocky, call it whatever you want, but Colton is performing the kind of R&D that will only serve to drive the industry forward.
“Call it fearless, call it cocky, call it whatever you want.”