Turbos - Turbo Accessories | 2020-2026 GM 6.6 Duramax L5P

The 2020–2026 6.6L L5P Duramax uses an electronically controlled BorgWarner variable-geometry turbocharger, but there is an important split within these model years. The 2020–2023 trucks use the original L5P turbo design, while the higher-output 2024 and newer L5P received a substantially revised turbocharger.

Both use variable turbine geometry and provide exhaust-brake operation, but the 2024 redesign includes changes to the turbine wheel, turbine housing, center section, bearing arrangement, mounting, and electronic actuator. Turbochargers and related components shouldn't automatically be assumed to interchange between the two versions.

How the L5P Turbo Changed the Duramax

The L5P turbo was already a major departure from previous Duramax generations. Earlier LLY, LBZ, LMM, and LML engines used Garrett variable-geometry turbochargers. With the L5P, GM moved to a BorgWarner VGT with an electronically controlled vane actuator.

The movable vanes around the turbine wheel allow the turbo to change how exhaust energy is directed through the turbine. At lower engine speeds, closing the vanes increases exhaust velocity and helps the turbo respond quickly. As engine speed and load increase, the vanes open farther to provide additional exhaust-flow capacity.

Those vanes also provide the L5P's exhaust-brake function. When exhaust braking is requested, the ECM commands a more restrictive vane position to increase backpressure while the transmission can select a lower gear to increase engine speed and braking force. It's particularly useful when controlling a loaded truck and trailer on a long descent.

What Changed for 2024?

The 2024 model year brought the biggest turbo change of the 2020–2026 run. Engine output increased from 445 horsepower and 910 lb-ft of torque to 470 horsepower and 975 lb-ft, with several turbo and airflow changes helping support the additional output.

The updated turbo uses a revised turbine housing and turbine wheel. The turbine changed from an 11-blade to a 10-blade design, and the turbine outlet was enlarged. The compressor dimensions remained much closer to the previous design, with much of the development focused on improving exhaust-side flow and response.

The electronic vane actuator was also revised to provide faster, stronger vane movement. That allows quicker control as airflow demand changes and contributes to stronger exhaust-brake performance. GM also made supporting engine changes, including stronger exhaust-valve springs.

Physical differences include a different turbine-housing mounting flange, revised pedestal arrangement, center-housing and compressor-back-plate changes, and a different 360-degree thrust-bearing arrangement.

That means a 2024-and-newer turbo shouldn't be treated as a direct replacement for a 2020–2023 unit simply because both engines carry the L5P name.

Upgrading the Factory VGT

The factory L5P turbo has to balance quick response, airflow under load, boost control, exhaust braking, emissions-system operation, and everyday drivability. That's why simply installing the biggest turbo available isn't always the best approach for a street or tow truck.

For many owners, a drop-in upgraded VGT offers a useful middle ground. More compressor and turbine flow can increase power potential while retaining electronic vane control, response, and exhaust-brake functionality.

The BD Screamer is one example for 2017–2023 L5P trucks. It uses a larger 66.2mm billet compressor wheel and 67mm turbine wheel in a stock-appearing drop-in VGT package. The larger wheels increase airflow and reduce drive pressure, giving properly supported L5P combinations additional power capability without requiring a completely different turbo arrangement.

The Fleece Performance 63mm Cheetah is another drop-in VGT option for 2017–2023 trucks. It combines a 63mm billet compressor with a 65mm turbine while retaining factory-style VGT operation and exhaust-brake functionality.

Calibrated Power's Stealth 67G2 offers another approach for applicable earlier L5P trucks, combining additional airflow with revised vane and turbine components while retaining the street-friendly characteristics of a VGT.

The advantage of these turbos isn't simply that they're larger. They give L5P owners room for more airflow and power while preserving much of what makes the factory VGT work well in a heavy pickup.

Don't Overlook the Airflow Around the Turbo

Replacing the turbo isn't the only way to improve the system.

The intake, turbo inlet, boots, clamps, charge piping, and intercooler plumbing all have to move and contain a considerable amount of air. Heat, age, towing, and increased boost can expose restrictions or weak connections in those areas.

The PPE Turbo Inlet Upgrade addresses the inlet side on applicable 2020 and newer L5P trucks by replacing the factory plastic inlet tube and resonator with a less restrictive path into the turbo. It's a relatively simple airflow upgrade for a stock or mildly modified truck and also works as a supporting modification for future upgrades.

BD's Turbo Intake Horn Kit takes a similar approach on applicable L5P trucks by improving the inlet path directly ahead of the compressor. Reducing restriction before the turbo can benefit the factory charger while also supporting an upgraded VGT later.

Stronger boots and clamps can help prevent charge-air leaks under load, while upgraded intercooler piping can improve and strengthen the path between the turbocharger, intercooler, and engine.

These upgrades give owners the ability to improve the airflow system in stages instead of jumping immediately to a complete turbocharger replacement.

Moving Beyond a Drop-In VGT

As horsepower goals climb, larger variable-geometry turbos, fixed-geometry conversions, and compound systems become options.

Fixed-geometry turbos can provide substantial airflow and eliminate the variable-vane mechanism, but they change low-speed response and typically give up the factory VGT-based exhaust brake. Compound systems can support considerably more airflow while maintaining good response when correctly matched, but they add plumbing, heat, tuning requirements, cost, and complexity.

Those tradeoffs may make sense on a serious performance build. For a street-driven or tow-focused truck, retaining a responsive VGT and exhaust brake can be much more valuable.

Turbo selection also needs to account for the rest of the truck. Fuel-system capacity, calibration, charge-air cooling, exhaust flow, transmission capacity, vehicle weight, elevation, and intended power level all affect which turbo makes sense.

Choosing the Right L5P Airflow Upgrades

A daily-driven L5P doesn't have to jump straight to a larger turbo. Intake, turbo-inlet, charge-air piping, boots, clamps, and intercooler improvements can strengthen the airflow system while retaining the factory charger.

For trucks that tow frequently or owners looking for another step in performance, an upgraded drop-in VGT adds airflow while retaining the response, vane control, and exhaust-brake characteristics that make the factory system so useful. Options such as the BD Screamer, Fleece Cheetah, and Calibrated Power Stealth show how much room there is to improve the factory-style VGT arrangement.

The model-year split remains important throughout the process. The 2020–2023 and 2024 and newer L5P turbo systems aren't identical, so intake components, turbo hardware, and replacement or upgraded chargers need to be selected for the correct application.

Whether the goal is helping the factory turbo breathe easier, improving a hard-working tow rig, or supporting substantially more horsepower, the L5P airflow system gives owners plenty of room to upgrade without having to change everything at once.