This 7-liter Duramax is not a stock-engine exercise. With a 5-liter Whipple supercharger, twin Precision turbos, two intercoolers, and high-rpm goals, the first priority is keeping the engine alive while we learn what the air system really does. That drove the switch to our Gen 1 military oiling system and a Banks wide-gear LML oil pump, because the enlarged piston cooling nozzles need more oil flow than a normal pump can comfortably supply. On the fuel side, the original twin CP3 plan gave way to a single 14mm SNS stroker pump fed by an Aeromotive brushless lift pump and regulator so low-pressure supply stayed right where we wanted it. With laboratory-grade Coriolis fuel flow meters in place, we can trust the data. The first loaded run was intentionally soft, but it still showed over 700 horsepower and well over 1,000 lb-ft. That tells us the combination is alive, the support systems are doing their job, and now the real tuning can start.
Gale Banks introduces the first fire of Banks' supercharged, twin-turbocharged, high-RPM 7-liter Duramax after months of development in Dyno Cell Number One. The engine had previously been shown outside the dyno room, but several important changes were made before this startup. The goal of this session was not full tuning, but a careful initial run to verify basic systems, establish oil pressure, build temperature, and gather the first meaningful data from the new combination.
One of the biggest changes was the switch away from the dry-sump system that had been shown earlier. Banks reverted to its Gen 1 military oiling system while a second-design dry-sump system is still being developed. Along with that change, the engine received a Banks wide-gear LML oil pump. Although Banks has never sold this pump, the company has built them for internal projects that require more oil-flow capacity than a standard pump can provide.
The added oil capacity was necessary because the piston cooling nozzles had been enlarged, which significantly increases oil demand. Before attempting to run the engine under load, Banks followed its normal first-fire procedure by cranking the engine specifically to confirm oil pressure and move oil throughout the system.
To improve turbine performance, Banks wanted to retain heat in the turbine housings. For that reason, turbine heat shields from Heatshield Products were added. The intent was to keep exhaust energy in the housings rather than allowing unnecessary heat loss.
The turbo plumbing and related fabrication also benefited from extensive hardware supplied by Vibrant. Banks describes the contribution as a large assortment of stainless components, including quality hose, HD V-band clamps, stainless steel mandrel bends, and 321 stainless expansion bellows. These parts were used throughout the plumbing system and reflect the level of fabrication required for a compound-boosted engine of this complexity.
The high-pressure fuel system was also substantially revised. The original plan used a pair of stock CP3 injection pumps, but that arrangement was reconsidered. In its place, S&S supplied a single 14 mm stroker pump. Banks' reasoning was that this pump could operate at 5,000 rpm pump speed, whereas the stock CP3-based approach was considered questionable at that speed range.
That change reduced the system from two high-pressure pumps to one, with the expectation that the larger S&S unit would still meet the engine's fuel demand. Because of the new pump arrangement, the front drive had to be refabricated and rerouted.
The low-pressure side of the fuel system also needed attention. The setup available in the dyno cell could not achieve the desired 15 PSI lift-pump pressure. To solve that, Banks turned to Aeromotive and installed one of its new-series brushless pumps, specifically a 5-gallon-per-minute unit. The system also received an Aeromotive regulator capable of controlling pressure accurately enough to deliver the target 15 PSI into the S&S pump.
For fuel measurement, Banks added two Endress+Hauser Coriolis fuel-flow meters, one on the supply side and one on the return side. The purpose was to obtain highly accurate fuel-flow data, with Banks characterizing the instrumentation as laboratory quality. That level of measurement is especially important on a new engine combination where fuel consumption and return flow need to be understood precisely during early testing.
With the revised systems in place, the team proceeded with the first fire. As expected, the first priority was oil pressure. After cranking, the engine lit off successfully and showed 41 PSI of oil pressure at an idle speed of 1,200 rpm. From there, the team began building temperature gradually.
At light load, cylinder pressure was reported at about 96 bar, which Banks considered encouraging. As the engine was held at 1,850 rpm, it produced about 45 horsepower while simply generating heat and stabilizing conditions. At that stage, the cooling tower was not yet online, so the run remained conservative until the dyno support systems were fully ready.
Once the cooling tower came online, the team prepared for the first loaded run. Banks emphasized that this was still an exploratory pass. Because the engine combines turbochargers, a supercharger, and two intercoolers, the team did not yet know the actual air-density output from the turbochargers, the blower, or the intercooling system as a whole. In other words, the boost system's real effectiveness still had to be measured rather than assumed.
For that reason, the first pull was intentionally soft. The plan was to run the engine to 3,800 rpm while targeting roughly a 25:1 air-fuel ratio, then stop and study the data. Banks made clear that the immediate objective was to learn how the new combination behaved rather than to chase maximum output on the first attempt.
During the pull to 3,800 rpm, the engine accelerated cleanly and the observed air-fuel ratio stayed in the 40s, indicating the setup was still very conservative. Even so, power climbed rapidly through 300 horsepower, then 400, 500, 600, and approximately 670 horsepower before the run was ended. Banks noted that he saw more than 700 horsepower and well over 1,000 lb-ft of torque on this first outing.
Those numbers were significant because they came from an intentionally cautious run on a completely new supercharged twin-turbo 7-liter Duramax combination. The result suggested that the engine was healthy, the major systems were functioning, and the platform had substantial headroom left for calibration work.
After the successful first run, Banks concluded that the project was ready to move into actual tuning using the MoTeC M142 ECM. The first fire had accomplished its purpose: verify oil pressure, confirm stable operation, bring the engine up to temperature, make an initial loaded pass, and collect baseline data.
The session ended with the team encouraged by the outcome and expecting much more development to come. The first run of the supercharged twin-turbo 7-liter Duramax established a strong starting point, but Banks made it clear that this was only the beginning of the engine's testing and calibration program.