What Is the L5P/L5D Duramax Turbo? Applications & Specs
The factory L5P/L5D turbo is a Garrett-sourced variable-geometry turbocharger (VGT) fitted to the 2017–2023 6.6L Duramax. If someone mentions the "VGT" on a newer Duramax tow rig, this is the turbo they mean.
Quick answer: The L5P/L5D factory turbo is a single VGT that uses movable turbine vanes and an electronic actuator to control boost and provide exhaust braking. L5P covers the earlier engine calibration and L5D denotes the emissions-hardware update introduced partway through the 2017–2023 generation — both use the same VGT operating principle.
Applications
The L5P/L5D VGT is the factory turbo on 2017–2023 6.6L Duramax engines in Chevrolet Silverado HD and GMC Sierra HD trucks. True North Turbos builds drop-in 64/67 and 67/67 replacements that cover the full range.
How the variable geometry works
Instead of a wastegate, the L5P/L5D turbo uses a ring of pivoting vanes in the turbine housing. An electronic actuator adjusts vane angle: closing them speeds exhaust gas across the turbine for quick spool and strong low-end torque (and enables exhaust braking), opening them to flow more air at higher RPM. That's why these trucks feel responsive from idle yet keep breathing under heavy load.
Strengths
- Strong low-end torque and fast spool for towing.
- Integrated exhaust brake.
- Factory-rated around 445 hp and 910 lb-ft on most L5P/L5D trucks, among the highest factory diesel truck outputs of its era.
Known weak points
- Vane sticking from carbon and soot build-up, especially on trucks that see a lot of idle or light-load driving.
- Actuator wear and calibration faults over time.
Both are covered in depth in L5P/L5D VGT Actuator & Turbo Problems.
How to identify it
The L5P/L5D VGT sits at the rear of the engine with the electronic actuator mounted directly to the turbo housing. If you're shopping for an upgrade, see How to Lower EGTs on an L5P Duramax for the towing-specific case for upgrading.
Frequently asked questions
Is the L5P turbo the same as the L5D?
They use the same VGT operating principle. L5D denotes the emissions-hardware update introduced partway through the 2017–2023 generation; both are commonly grouped together since they share the same turbo footprint.
What does VGT mean?
Variable Geometry Turbocharger — a turbo whose turbine vanes move to control exhaust flow, boost, and exhaust braking, instead of using a wastegate.
Can the L5P/L5D turbo be upgraded?
Yes — with a billet compressor wheel/rebuild or a drop-in replacement for more airflow and power.