We kept slowing the supercharger on our supercharged twin-turbo Duramax, and the engine kept making more power. Out of the box it made 820 horsepower. With less blower speed it went to 956, then 1,007, and with more fuel it reached 1,172 and finally 1,218 horsepower. That sounds like a win until you look at what the data is telling us: the turbos were not increasing their contribution through those tests. If power rises while blower contribution falls, the system balance is wrong. The big lesson is simple—more boost from the blower is not automatically better, and a 1,200-horsepower result can still expose an air-path strategy that needs to be rethought.
The video returns to Dyno Cell Number One with Banks' supercharged, twin-turbo Duramax. The team is evaluating power output while changing blower speed and fuel delivery, and the early results reveal that the combination is behaving in an unexpected way.
In its initial configuration, the engine produced 820 horsepower.
That establishes the baseline before the team began reducing blower speed and making additional fueling changes.
As blower speed was reduced, horsepower increased instead of falling.
After the first reduction, output climbed to 956 horsepower. Slowing the blower further increased power again, this time to 1,007 horsepower.
The trend was counterintuitive because reducing supercharger speed would normally be expected to reduce the blower's airflow contribution. Instead, the Duramax continued making more power.
After seeing the gains from reducing blower speed, the team added more fuel.
With the additional fueling, output jumped to 1,172 horsepower. The focus then shifted toward determining whether more fuel would bring the turbochargers further into the combination and produce another significant increase.
With the engine already beyond 1,100 horsepower, the next target became 1,200 horsepower.
The team added more fuel to see whether the turbos would respond strongly enough to push the Duramax beyond that threshold.
The effort succeeded, with the engine ultimately producing 1,218 horsepower.
That represented a 398-horsepower increase over the original 820-horsepower configuration and confirmed that the combination responded dramatically to the changes in blower speed and fueling.
Despite reaching 1,218 horsepower, the test raised a larger engineering question.
Because horsepower continued increasing as blower speed was reduced, the team began questioning the compound air-system architecture itself. The current arrangement is described as turbos first and blower second, but the results suggest that strategy may be backward.
The next challenge is therefore not simply making more power, but understanding how the turbochargers and supercharger should interact to produce the most effective airflow and boost strategy for the Duramax.
