This 7L Duramax build is headed well past the supercharger-only stage. At roughly 700 horsepower, throttle response was already violent enough to twist off the supercharger input shaft, so the next step is a turbo pair that can come up fast and support much more airflow. The Precision 6870 Gen 2 setup fits that job with dual ceramic ball bearings, forged 2618 compressor wheels, and compressor-side anti-surge features. On this engine, the plan is to run the turbochargers into a charge air cooler, then manage bypass and pressure relief so boost can move around the supercharger when needed and the compressors stay out of surge when the throttle closes. The point is simple: quick response, stable boost control, and enough air to push this Duramax toward monster truck power levels.
This unboxing centers on a pair of Precision Turbo units intended for a Banks monster truck project built around a supercharged twin-turbo Duramax V8 diesel. The target is ambitious: roughly 1,250 to 1,400 horsepower, which is the range needed to be competitive in monster truck use. Up to this point, the engine has been running only the supercharger and has already reached nearly 700 horsepower.
That supercharged setup also revealed how violently responsive the engine is. Throttle response was quick enough that a sharp throttle input twisted off the supercharger input shaft. After upgrading that weak point, the next step is to add turbochargers and push the combination much harder. The turbos are therefore not a cosmetic upgrade but a key part of moving from a strong supercharged diesel to a much more serious compound-boosted competition engine.
The shipment includes two turbochargers along with supporting hardware. In the boxes are stainless V-band clamps, weld flanges, and fasteners, all packed with the turbos. The presentation leaves a strong impression of a company focused on racing hardware, and the discussion notes Precision Turbo's reputation in the performance and racing turbocharger market across both gasoline and diesel applications.
The turbos are described as dual ceramic ball bearing units, which places them firmly in the high-end performance category. That bearing arrangement is especially relevant for an application where rapid acceleration of the rotating assembly matters, because the engine in this truck needs the turbos to come up quickly rather than spend long periods at a steady top-end operating point.
Once unpacked, the turbine housing stands out immediately. It uses stainless construction with V-band connections on both the inlet and outlet sides. According to the referenced specification sheet, the turbine housing is a 310 stainless steel casting. That material choice is significant for a hard-used diesel racing application because turbine housings see extreme exhaust heat and repeated thermal cycling.
The overall build quality is emphasized throughout the inspection. The turbocharger is presented as tightly packaged, carefully finished, and clearly intended for serious motorsports use rather than generic replacement duty. Even before discussing wheel sizes or airflow, the hardware gives the impression of a purpose-built racing component.
The compressor side includes several notable features. There is a boost reference port, a streamlined compressor nut, and carefully deburred and finished openings. The inlet treatment is described as an anti-surge style arrangement integrated into the compressor cover, intended to improve compressor behavior under demanding transient conditions.
The compressor wheel itself is identified as a 2618 forged wheel. That distinction is treated as important. While enthusiasts often refer to "billet" wheels, the explanation here is that a billet wheel is typically machined from round stock, whereas a forged wheel has a different grain structure and is considered superior for this kind of high-performance use. In other words, the wheel is not just visually impressive; its manufacturing method is part of why it is suited to a severe racing environment.
These turbochargers carry a 6870 designation. In the explanation given, that refers to a 68 mm compressor inducer bore and a 70 mm turbine exducer bore. Those dimensions place the turbos in a range that should support substantial airflow while still responding quickly enough for the intended vehicle.
That balance matters in this application. A monster truck diesel does not simply sit at peak power for long stretches; it needs the turbo system to accelerate rapidly and respond immediately to throttle changes. The expectation is that this size will be the right match for the truck's operating style, combining strong airflow capability with the transient response needed in competition.
Each turbo is said to provide enough air to support about 1,100 horsepower on gasoline, giving the pair a combined gasoline airflow capability of roughly 2,200 horsepower. That figure is not presented as a direct diesel power claim, but as a useful reference point for the amount of air the pair can move.
For the Duramax project, the real question is how that airflow translates in a diesel compound-boost arrangement with the existing supercharger. The stated horsepower target of 1,250 to 1,400 suggests that the turbo pair should have enough headroom for the intended build while still fitting the response requirements of the truck.
Precision offers different compressor cover configurations, and this version appears to use a 4-inch inlet. On the discharge side, this particular cover has a nominal 2.5-inch outlet, although another version is mentioned with a 3-inch outlet. For this build, the 2.5-inch discharge is considered appropriate for the planned plumbing.
Those connection sizes matter because the turbo system is being integrated into a custom fabricated intake path rather than a simple bolt-on arrangement. The hardware now needs to go to the fabrication shop so the ducting can be built around the chosen compressor cover and outlet dimensions.
The planned system routes the turbocharger compressor discharge into a charge-air cooler. In this configuration, that cooler is described as a true intercooler because it sits between two boosting devices: the turbochargers and the supercharger. The airflow path is therefore more complex than a conventional single-stage turbo system.
The design also includes bypass valves in the plenum feeding the charge-air cooler. Those valves will allow boosted air to bypass the supercharger and go directly into the intercooler under the appropriate conditions. That detail is central to making the compound system work efficiently, because it manages how the turbochargers and supercharger interact instead of forcing all compressed air through the same path at all times.
Surge control is addressed in more than one way. The compressor inlet itself incorporates an anti-surge style feature, but the overall system will also use pressure-relief hardware downstream. After the supercharger, there will be a pressure relief valve so that when the throttle is closed, the compressors are not driven into surge.
That means the final installation is being designed around transient behavior as much as peak airflow. In a vehicle with extremely sharp throttle response, sudden throttle lifts can create damaging pressure events if the system is not managed correctly. The combination of anti-surge compressor cover features, bypass valves, and pressure relief valves is intended to keep the compound-boost system stable during both acceleration and throttle drop.
The conclusion of the unboxing is that these Precision Turbo units appear exceptionally well executed, both mechanically and cosmetically. The stainless turbine housing, forged compressor wheel, ceramic ball bearing center section, and detailed machining all reinforce the impression that they are serious racing components.
More importantly, they appear to fit the engineering needs of the project. The turbos are sized for fast acceleration, offer substantial airflow capacity, and provide the connection options needed for the custom compound-boost plumbing on the Duramax monster truck engine. With the supercharger already proving the engine's responsiveness and exposing drivetrain weaknesses, these turbos represent the next major step toward the project's 1,250 to 1,400 horsepower goal.