HEADLINES: Fluke Failure Or Growing 3.0L Dmax Problem?
Is the 3.0L Duramax a ticking time bomb? Plus, Josh McCormack squeezes 1,000 hp out of a VGT (on a 6.0L) and a Cummins-swapped Chevy sees instant success in the dirt.
With just 5,700 miles on the clock, the LZ0 Duramax in this '23 GMC Sierra 1500 Denali failed castrophically.
A loud pop while cruising down the highway, followed immediately by a low oil pressure warning landed this 3.0L Duramax-powered, 5,700-mile, ’23 GMC Sierra 1500 Denali on the side of the road. The owner alluded to a cracked block, a possible blown rear main seal (which isn’t unheard of for the baby Dmax) or the result of a broken variable flow oil pump belt. If you remember, that crank-driven belt (not chain) is located at the rear of the engine. Given that the failure occurred on a ’23 model leads one to ponder if this problem could be exclusive to the LZ0 version (not the earlier LM2), the LZ0 Duramax having been turned up to 305 hp and 495 lb-ft of torque for the ’23 model year. Time may be the only way to tell.
Spray & Pray
Four-Digit Horsepower Out Of A 63mm VGT
Time for one last news bit from the Scheid Diesel Extravaganza. When Josh McCormack strapped his 6.0L Power Stroke to M&M Repair’s mobile chassis dyno, he was expecting his Super Duty to make 875 to 900 hp. Even then, that was leaning on the engine pretty hard—a 6.0L pulled from an ambulance and fitted with used ARP 2000 head studs, a fresh Fleece Cheetah VGT and 205/30 Warren Diesel injectors—especially since he planned to throw two .110 nitrous jets at it, along with an old-fashioned ghetto fogging. When the rollers stopped turning, Josh’s dyno graph showed 1,088 hp and 1,527 lb-ft.
Truck Pulling
1 Hook, 1 Win
In what amounted to perfect timing, Lee Stiltz’s ’05 Silverado debuted a brand-new Freedom Racing Engines Cummins power plant at the 14th annual Fleece Performance Engineering “Hoosier State Showdown” over the weekend. After campaigning a Duramax for many years, Lee turned to the common-rail experts at Freedom (the engine building arm of Fleece) for a bullet that could immediately get him into the winner’s circle. Right out of the gate, the MoTeC controlled and S&S-fueled Cummins earned its first Pro Street class victory. WCFab, Harts Diesel and Kenny’s Diesel are also part of what should be a winning combination for years to come.
Drag Racing
Diesel Vs. The World
It was an eventful trip to the 2023 Yellowbullet Nationals for Ryan Milliken, and his Cummins-powered ’69 Nova continued to show signs of improvement in X275. During Q3, the car nabbed a 1.08-second 60-foot and pulled off a 2.81-second sprint to 330 feet before crossing the eighth-mile stripe in 4.19 seconds (at 177 mph), which marks a new personal best with the sun in the sky. The qualifying pass was enough to earn him the number 6 spot on the ladder. And even though Ryan would get beat on the tree in the first round of eliminations (in a 4.22 vs. 4.22 race), loads of data was collected and plenty of things were learned. Look for Ryan and his pot-stirring Nova to shake things up at the Race of Thrones/No Mercy event in October.
OEM
Cummins Advances Its Series 850 Holset Turbo Technology
Cummins has announced four advancements in the turbocharger assemblies found on engines ranging from 15L to 95L in size. The company’s Series 850 Holset turbos will now feature an enhanced version of its high pressure ratio compressor (HPRC), originally released in 2020, for higher all-around efficiency and improved altitude capability. Improved performance as well as durability was achieved with a new inverse impeller design, a vaneless design offers an optimized map width at higher pressure ratios, and a thin wall, stainless steel compressor cover offers a notable weight reduction over previous, cast-iron versions. Cummins’ 850 Holset turbochargers can be found on off-highway engines used in power generation, agriculture, marine, mining, oil and gas, rail, and construction.
