The hard part isn’t just bolting a Whipple onto an L5P. It’s packaging a supercharger, intercooler, drive system, and plumbing into a layout that can become a real turnkey engine for customer trucks. We reworked the original setup to get the blower height down, moved from a rear-inlet concept to a front-inlet/front-drive arrangement, and biased the intercooler rearward while shifting the supercharger forward. That keeps room for the factory high-pressure fuel pump in the valley, preserves intercooler area where we need it, and gives the blower a straighter inlet path with less complication up front. The result is a lower, cleaner package aimed at real hood clearance, better belt engagement, and a layout we can actually build around.
This episode returns to the LockJaw Duramax build and focuses on the intercooler and supercharger packaging now that the cab has been separated and set onto the Roadster Shop chassis. The work is being redirected toward a configuration that does more than fit this one-off truck. Banks wants the LockJaw hardware to serve as the predecessor to a future L5P turnkey crate-engine program, so the packaging decisions being made here are intended to reflect what customers could realistically install in their own trucks.
That shift in direction is being led by Matt, the newest member of the mechanical engineering group. Although he comes from aerospace and gasoline-engine backgrounds and is new to diesel-specific work, he has been tasked with managing the crate-engine program and reviewing the entire intake, intercooler, and supercharger system. Rather than continue with the previous concept unchanged, he went back into CAD, re-evaluated the layout, and began another iteration cycle using design work, 3D-printed mockups, and physical fit checks to determine what clears, what interferes, and how low the assembly can be packaged.
The most obvious change is height. Compared with the earlier cast marine manifold setup, the new printed manifold sits dramatically lower, by roughly six to eight inches or possibly more. The previous marine manifold used Gale's cylindrical intercooler core and was physically massive. While that concept was impressive, it was too tall for the broader packaging goals now driving the project.
The new manifold is being designed around hood clearance as a primary constraint. LockJaw itself is less sensitive to protruding through the hood, but a turnkey engine intended for customer installations cannot assume that freedom. The current target is to keep the distance from crank centerline to the top of the blower roughly in line with an LSA-style package, which should allow the assembly to clear the hoods of many restomod trucks. That requirement heavily influenced this manifold, intercooler, and supercharger iteration and is central to making the engine a viable alternative for builders who already know they can fit an LS but want a diesel option instead.
Another major revision is the supercharger orientation and inlet strategy. The team is moving away from the previously discussed rear-inlet arrangement and will not use a jackshaft. After working with Whipple, Banks chose a front-drive, front-inlet configuration. The manifold shown is still a 3D-printed representative part, but it reflects the direction of the final system.
This change simplifies the inlet path considerably. Earlier thinking involved more complicated routing that would have required custom tubing to snake around the chassis and bodywork, potentially including ovalized tubing and carefully radiused transitions to control pressure drop into the blower. With the new layout, the intake path can be much more direct, essentially a cleaner shot from the air filter into the supercharger. That should reduce complexity, improve packaging, and better suit a turnkey engine that needs to be repeatable across customer installations rather than tailored only to one custom truck.
Although the front-drive system is not fully finalized in CAD, the current model shows where the drive will live. The supercharger drive is being positioned more or less concentric with the driver's-side rotor of the twin-screw Whipple unit. That establishes the basic geometry for the front-end accessory and blower-drive layout.
The CAD model also shows an extra-large pulley arrangement intended to set the blower drive ratio while maximizing belt wrap. The plan is to use a 12-rib belt system and retain as large a supercharger pulley as possible, around three inches, to ensure adequate belt engagement and minimize slip. That matters because the engine will see meaningful RPM, and a high-load supercharger drive with insufficient wrap would quickly become a reliability problem. The drive system is therefore being designed not just for fit, but for stable power transmission under real operating conditions.
The intercooler packaging is constrained by one of the L5P's defining features: the factory high-pressure fuel pump sits in the valley. Even though it is hidden on a stock engine, it becomes a major obstacle when trying to place a large intercooler core beneath a supercharger. The team wants to retain the factory high-pressure pump in its stock location, including room for its fittings and sensors, while still providing enough intercooler area to remove the heat generated by compressing the intake charge.
The solution under development is to bias the intercooler rearward and the supercharger forward. That works because the twin-screw blower's outlet is effectively centered even though the blower body spans a larger area. Matt describes the outlet as a delta-shaped opening on the bottom of the blower that discharges near the center of the engine. Reversing the blower orientation also moves that delta opening from the front of the engine to the rear, which improves how the outlet aligns with the intercooler and valley packaging. The result is a compromise-driven layout in which each component gives up some ideal position so the whole system can coexist.
The intercooler itself is expected to be a single-pass core. The water inlet and outlet will likely be packaged at the rear, either through direct fittings or through a small water manifold that routes coolant into and out of the core before sending it to a front-mounted heat exchanger ahead of the radiator. That plumbing is still being iterated, but the basic cooling architecture is already defined.
With the cab now sitting on the chassis, even temporarily on blocks, the mockup is already helping the team judge vertical and fore-aft clearances. The current setup appears promising enough that hood clearance may be achievable, reinforcing the value of the lower manifold and blower package.
The chassis mockup is also important because the Allison transmission behind the L5P will require firewall trimming. Rather than cutting blindly and repeatedly test-fitting, the team can now use the mocked-up engine and transmission position to estimate how much material needs to be removed on the first pass. That should save fabrication time while avoiding unnecessary cuts that would create extra work later for Sean, who will handle substantial sheet-metal fabrication. The goal is to get the truck to him with enough confidence in the package that his finished work will not be invalidated when the final engine and production-intent parts are installed.
The schedule is tight. At the time of filming, it is early June and the target is SEMA at the beginning of November. The truck needs to get to Sean in July, which leaves only a short window to finalize major packaging decisions and complete enough mockup work to support fabrication.
A great deal remains unfinished. The engine currently in the chassis is not the same engine previously shown on the dyno; that earlier engine will return to dyno duty, while this one serves as a space-claim mockup for packaging and sheet-metal development. Beyond the manifold, blower, and intercooler, the team still needs to complete the supercharger drive, inlet tubing, front-end accessory drive, exhaust manifolds, and additional plumbing. The FEAD alone is a substantial task. It must be designed in CAD, printed, mocked into place, and potentially revised, all within roughly four weeks so the surrounding fabrication can proceed. The discussion compares the expected complexity to the heavy custom FEAD used on Banks' super-turbo setup, including major bracketry built from thick plate.
One of the more significant strategic changes is the oiling system. LockJaw had previously been discussed as a dry-sump build, but in an effort to align the truck more closely with the turnkey engine program, the team is now attempting to package it as a wet-sump engine. That would make the final architecture more relevant to customer applications, but it introduces new clearance challenges.
The first wet-sump fit attempt did not clear the steering rack. After installing the pan, the team found interference and removed the lower section, leaving the mid-pan and pickup in place. The pickup clears, but the front of the pan will need additional clearance where the steering rack passes. Several options are still being explored to make the wet-sump arrangement work. If they succeed, the space that would otherwise have been occupied by the dry-sump pump can be repurposed, potentially for the air-conditioning compressor. That would allow the truck to retain air conditioning while also simplifying the engine package in a way that better matches the intended turnkey offering.
Taken together, the changes show that LockJaw is no longer just a custom showcase truck. It is becoming a rolling packaging study for a Banks L5P crate-engine program. The lower manifold, front-inlet Whipple arrangement, centered intercooler strategy, 12-rib blower drive, firewall planning, and wet-sump investigation are all being evaluated not only for performance and fit in this chassis, but for how well they translate into a repeatable engine package customers could actually use.
The engineering process is explicitly iterative. CAD models, printed mockups, physical fit checks, and supplier collaboration are all being used in real time to narrow the design field. The immediate objective is to lock down enough of the package to hand the truck off for fabrication, but the broader objective is to turn the lessons from LockJaw into a practical, installable supercharged L5P platform.