The real story here is simple: racers want more, but they also want to know what the engine is doing when the load comes on. That is why this L5P Duramax conversation lands on the same things we focus on every day—airflow, oil control, combustion data, and usable electronics. Al Unser Jr. has a long history with our diesel systems going back to the early turbo Ford days, and now he is back with a Chevy L5P for a Banks Derringer Tuner setup. The point is not just adding power. It is adding it with real information behind it. With iDash data logging, you can see what changed, how the engine responded, and whether the combination is actually working. That is how you build a truck for somebody who knows the difference between noise and performance.
Alan Unser Jr. visits the Banks facility in Fenton and remarks on its scale, noting that multiple buildings carry the Banks name and that the operation spreads across the neighborhood. Gale Banks frames the visit as a walk through the company's engineering work, with the discussion quickly moving from the size of the campus to the hardware and development programs underway there.
The visit is presented less as a showroom tour than as an overview of how Banks develops diesel and gasoline performance systems. Gale emphasizes that the company's work spans mechanical design, airflow development, electronics, calibration, dyno testing, and vehicle validation. That broad scope sets up the rest of the conversation, which moves from heavy-duty diesel engine components to airflow modeling, combustion analysis, and complete vehicle testing.
One of the first components discussed is a lower crankcase assembly for the L5P Duramax. Gale explains that it replaces the stock lower crankcase on the bottom end and serves multiple purposes. It increases oil capacity, and it also incorporates a windage-management system intended to control the oil and air being whipped up by the rotating crankshaft.
As the crank rotates, it drives oil and air downward into the sump area. The design then routes the air back while allowing the oil to separate out underneath in a cast-aluminum pan. Gale describes this as part of a broader effort focused on what is happening inside the L5P's lower end, not just for durability but for oil control and high-performance use.
That work extends to a new stroker crankshaft for Duramax engines. Gale points out that the crank uses larger crank pins, which he refers to as the Banks Big Pin. The larger pin size makes the crankshaft substantially stronger, but it also forced Banks to develop its own rod bearing from scratch. He notes that designing a rod bearing sounds simple until one attempts it; in practice, it is difficult enough that few companies outside major OEMs such as GM, Ford, or Chrysler would take it on. The intended applications include marine engines, race engines, and diesel competition builds, reflecting how far these engines are now being pushed beyond pickup-truck duty.
Gale describes how diesel engines are now being installed in a wide range of vehicles, far beyond their original pickup-truck applications. He mentions builders putting diesels into race cars and even Chevrolet Chevelles, underscoring how the diesel performance world has expanded into custom and motorsports projects.
That evolution connects to an older chapter in Banks history. Alan recalls that diesel pickups once did not come with turbos, and Gale confirms that Alan's father was among the first to ask for a turbo system on one of those trucks. Gale built it, and similar systems followed for other family trucks and tow rigs. The discussion turns to the Unser family's long-running habit of towing snowmobiles, Jet Skis, and other toys with turbocharged Ford Excursions and similar vehicles, often turning towing into an informal competition. Gale recalls Alan's father calling to say that the younger drivers were starting to catch him and that he needed more power. That anecdote illustrates how Banks' diesel work grew out of real towing demands as much as racing ambition.
From there, Gale shifts to a core engineering principle: airflow. He explains that whether the project is a diesel or a gasoline engine, performance development starts on the airflow bench. Cylinder heads matter, but so do the intake manifold, ducting, turbo plumbing, and every restriction or transition that affects how air reaches the engine.
Banks uses in-house design and rapid prototyping to develop those parts. During the tour, Gale points to a new Camaro project built around a turbocharged four-cylinder and a six-speed transmission. A 3D printer is producing an air-filter housing for that program. Gale says he does not like the typical aftermarket approach to cold-air intakes, implying that Banks is pursuing a more engineered solution rather than simply replacing parts for appearance or sound.
The CAD systems shown during the tour display intake ducting and other airflow components in development. Gale also points to marine-engine layouts on screen, including older twin-turbo and supercharged marine combinations that Banks sold for decades. The point is that airflow development at Banks is not isolated to one platform; the same design process applies across diesel trucks, gasoline performance cars, and marine engines.
The conversation then turns to more extreme engine combinations. Gale shows a diesel V8 fitted with open zoomie-style exhausts, noting that people rarely hear a diesel V8 this way because turbochargers normally muffle much of the sound through the turbine. Once the basic setup is sorted, the plan is to replace the zoomies with tubular stainless exhaust plumbing feeding two turbochargers.
Those turbos will then blow into a supercharger, creating a turbo-supercharged compound-boost arrangement. Gale says Banks has already used this concept at Pikes Peak on a Freightliner diesel. In that project, a large diesel engine was installed in a semi tractor but dropped about a foot and moved rearward roughly seven feet, effectively turning the truck into a mid-engine vehicle. Gale's point is that moving the engine transformed the tractor's dynamics in the same way mid-engine placement transforms a race car.
He describes the Pikes Peak run as especially difficult because the team drew an afternoon time slot and encountered snow, hail, rain, gravel, and debris across the road. The course was 12.5 miles long with 166 corners, and the vehicle weighed roughly 10,000 to 12,000 pounds. Even under those conditions, the truck completed the climb in about 12.5 minutes. Alan compares that with his own 1983 overall-record run at Pikes Peak in a much lighter open-wheel Wells Coyote chassis on the old dirt surface, noting how little grip those cars had. The comparison highlights the scale of what Banks achieved with a heavy diesel truck.
Back in the engine-development area, Gale explains how Banks instruments engines during dyno work. On the diesel V8 under development, the team is measuring exhaust gas temperature on every cylinder and also monitoring air-fuel ratio on all eight cylinders. The goal is to evaluate flow balance in the intake manifold under the blower so that all eight cylinders are doing the same work rather than operating unevenly.
The tour then moves into the dyno control room, where Gale points out that Banks uses cylinder-pressure measurement as a major development tool. He notes that NASCAR and IndyCar teams use this kind of data, and Banks applies it as well. A compact device called the Chi box allows cylinder pressure to be measured not only on an engine dyno but also in a vehicle.
Cylinder-pressure data reveals how combustion pressure builds as the piston moves, which allows timing to be optimized far more precisely than with conventional methods. It also shows how combustion progresses through the chamber, making it possible to evaluate changes to combustion-chamber shape or piston dome design. The objective is to burn more of the fuel charge effectively and produce the greatest pressure rise from the same amount of fuel. Gale's explanation makes clear that Banks is not just adding hardware; it is using advanced combustion analysis to understand why a change works.
That same emphasis on measurement carries into Banks' aftermarket electronics. Gale shows Alan a gauge system intended for his truck and says it can perform many of the same monitoring and logging functions used in development. For customers experimenting with larger turbos, intake-manifold changes, cold-air systems, or bigger intercoolers, the gauge can log what the engine is doing rather than leaving them to guess whether a modification helped.
According to Gale, the system can record up to 100 different channels at 10 samples per second for as long as four hours, using a small SD card. The data can be played back directly on the gauge or exported for on-screen analysis. He compares that process to race engineering, where data is reviewed immediately after a practice run. The point is to give hard-parts development a factual basis: not whether a part sounds louder or feels different, but whether it actually changed measurable engine behavior.
The electronics lab shown later in the tour handles the full chain of development. Banks starts by defining what a product needs to do, then develops the circuit-board hardware, the embedded code that runs the device, and the calibration overlay that determines how it behaves in a specific application. The tour emphasizes that hardware, software, and calibration are all developed in-house.
The Camaro project returns as a concrete example of how those tools and methods come together. The car uses a 2.0-liter turbocharged four-cylinder gasoline engine rated at 275 horsepower in stock form, and Gale says the target is about 400 horsepower. Because it is a four-cylinder, the engine is lighter than a V8, which improves front-end weight distribution and helps the car handle better than the nose-heavy V8 variants.
One of the key systems on the engine is a water-methanol injection setup mounted at the front of the engine. Gale explains that the system injects water and methanol under high boost to suppress detonation and cool conditions inside the cylinder. That cooling effect allows the engine to run more boost on the same fuel. He describes detonation as the limiting factor in boost pressure, making charge cooling and octane enhancement critical.
Methanol contributes additional octane and burns very cool, while the water adds further cooling. Gale describes the two as working together: more octane permits more boost, and lower temperature also permits more boost. Although Alan initially treats the combination as unusual, Gale notes that water injection is more than a century old, dating back to early aviation use in the 1910s and later appearing on World War II fighter aircraft. What Banks is doing differently, he says, is managing the system with modern controls rather than merely reviving an old idea.
The tour concludes in the chassis-dyno and electronics areas, where Gale shows a 2017 Chevrolet Silverado 3500 dually with the L5P Duramax. He also mentions a 2500 4x4 in the program. Alan is pleased to see the Chevrolet Duramax platform represented because it matches the truck he wants to build with Banks.
The chassis dyno uses dual rollers with both rollers driven, and Gale notes that each side is equipped with a 750-horsepower absorber. That setup allows Banks to test heavy-duty trucks under controlled load while validating both mechanical and electronic changes. The implication throughout the visit is that the same engineering process shown in the facility-from CAD and prototyping to combustion analysis, electronics, and dyno validation-will be applied to Alan's truck.
Alan closes by explaining why his family has repeatedly turned to Banks over the years: the company's strength is innovation and technical depth. Gale, now 75, says the work is what keeps him engaged. The visit ends with the expectation that the development underway at the facility will eventually make its way onto Alan Unser Jr.'s Duramax-powered truck.