On this supercharged twin-turbo 7L Duramax, the blower does the low-speed work, but it becomes the restriction once boost and outlet temperature climb. We found the supercharger was effectively tapped out around 20 to 22 psi because heat was the problem, not just airflow. The fix is to bypass the blower once the turbos are online and send that boost air into the intercooler under the blower. That puts the wastegate strategy front and center. The Turbosmart Gen-V wastegates use boost pressure against a spring and diaphragm to lift the valve off the seat, and we’re adding valve position indicators so we can see exactly what the valve is doing. We also spec’d larger actuator heads on the 45mm gates so exhaust pressure doesn’t blow the valve open early. More diaphragm area lets us run more spring and keep the valve shut until we want it open. The Big Bubba blow-off valve handles pressure relief on the system, with electronic control available through Turbosmart hardware or our AutoMind ECM. The point is simple: control the bypass, control the heat, and keep the compound-boosted Duramax working where each device does its best job.
This installment of Banks Unboxing focuses on Turbosmart wastegates and related boost-control hardware selected for a twin-turbo monster-truck engine build. The purpose of the system is not simply to regulate turbocharger boost in a conventional layout, but to manage airflow around a supercharger once the turbos are fully online. In this configuration, some of the boosted air will bypass the blower and route directly into the intercooler beneath it.
The supercharger remains in the system to provide immediate low-speed response when the throttle is opened, but it is no longer expected to carry the engine at high power by itself. According to Gale, the blower is effective for initial torque and response, yet it does not have enough capacity to support much beyond roughly 700 horsepower. That limitation drove the decision to transition airflow around the blower once the turbo system is producing sufficient boost.
The main constraint on the supercharger was outlet temperature. During testing, the team reached about 20 to 22 pounds of boost, at which point the blower was effectively at its thermal limit. The concern was not just reduced efficiency, but mechanical risk inside the supercharger itself.
As outlet temperature rises, the rotors can expand. If that thermal growth becomes excessive, the rotors may contact the case or each other, causing severe damage. To avoid that condition, the build uses a bypass strategy: once the turbos are online, the system diverts part of the compressed air around the supercharger rather than forcing the blower to continue operating in a range where outlet temperature becomes unacceptable.
One of the key components shown is a Turbosmart WG60 GenV wastegate. Gale identifies it as the bypass valve for the system and emphasizes its size and seriousness, noting that it uses a 60 mm valve. The package also includes the associated clamps and flanges needed for fabrication, with the valve seat intended to be welded into the system.
He then explains the basic operating principle of the wastegate. Inside the assembly is a diaphragm and a spring. Boost pressure acts against the diaphragm, and when that pressure overcomes the spring force, the valve lifts off its seat. In a basic setup, that establishes the pressure at which the valve begins to open. In a more advanced control strategy, the opening behavior can be modulated so the boost threshold and valve action are actively managed rather than fixed.
For this particular unit, the spring is said to be set at about 26 PSI. In practical terms, that means approximately 26 PSI of boost will begin to lift the valve from its seat. That is the baseline wastegate function before any additional electronic control strategy is layered on top.
A notable detail in this build is the addition of valve-position indicators on the wastegate heads. The goal is to know exactly how far the valve is off the seat at any given time, rather than inferring valve behavior only from pressure data.
The sensor package shown appears to use an integrated electronic device that Gale describes as likely being a proximity detector. It mounts at the upper end of the valve assembly and threads into place to provide accurate measurement of valve movement. This instrumentation gives the team direct feedback on wastegate position, which is especially useful when calibrating a complex bypass system where precise control of airflow around the blower matters.
The unboxing also includes a pair of smaller Turbosmart wastegates with 45 mm valve size. Although the valve itself is smaller than the 60 mm unit, Gale requested a custom configuration with a larger actuator head. He specifically prefers these larger-head wastegates because of issues he has encountered with smaller actuators in high-exhaust-pressure applications.
His explanation centers on diaphragm area and spring control. A smaller actuator generally means lower spring seat pressure and lower spring rate. Under those conditions, exhaust pressure can become high enough to blow the valve off the seat before the desired control point is reached. By increasing diaphragm area, the wastegate can use more spring force while maintaining proper control authority. The result is a valve that stays firmly seated until the intended opening condition occurs.
He notes that the unusual appearance of the actuator head is intentional and reflects exactly how he wanted the part configured. Two of these custom 45 mm units are included for the project.
Another major component in the package is a large Turbosmart blow-off valve controller assembly. The blow-off valve itself is described as a very large unit with a substantial valve and a piston that lifts to open the discharge port. The emphasis is on its physical scale and flow capability, suggesting it is intended for a very high-output forced-induction application.
The mounting arrangement uses a weld flange with an O-ring seal at the bottom. Gale also points out that this is an older two-outlet design. Alongside the valve is an electronic control component, identified as a control valve, which is used to command the blow-off valve. Rather than functioning as a purely passive pressure-relief device, this setup appears intended for controlled operation through an external strategy.
For system control, the team is considering either Turbosmart's own control systems or Banks' AutoMind ECM. That means the wastegates and blow-off hardware may be electronically managed rather than left to spring pressure alone. The earlier explanation of wastegate modulation ties directly into this approach: once electronic control is added, boost threshold and valve behavior can be varied to suit operating conditions.
Gale also references another active program, the Killin' a Duramax project, where a Turbosmart wastegate and Turbosmart controller are already in use. He reports that the combination is working well there. That existing experience appears to support the decision to use Turbosmart hardware not only on the monster-truck engine program but also across other Banks development efforts.
The recap closes with Gale's assessment of the hardware itself. He describes the Turbosmart components as exceptionally well made, comparing them to jewelry. His praise is directed at several engineering details: the alloys used in the valves and castings, the heat shielding designed to keep the actuator head and diaphragm cool, and the overall thoughtfulness of the product design.
He also highlights a practical packaging feature: the actuator heads can be clocked so the fittings point in whatever direction the installation requires. That flexibility matters in crowded custom engine bays where routing lines and packaging control hardware can be difficult. Taken together, the material choices, thermal management, configurability, and control options are presented as the reasons Banks is using this equipment on both the monster-truck engine and the Killin' a Duramax program.