The L5P is the strongest factory Duramax turbo platform yet, found in 2017-2023 Chevrolet Silverado HD and GMC Sierra HD trucks (with the related L5D covering GM's medium-duty 4500HD-6500HD chassis cabs). This guide covers everything: model years, factory specs, the problems owners actually run into, how much power the stock turbo can handle, and the upgrade paths that make the most sense for towing, daily driving, or a serious build.
Quick answer: The L5P Duramax (2017-2023) makes 445hp/910 lb-ft from the factory and uses a BorgWarner variable-geometry turbo that's strong for a factory unit but still a bottleneck once you start towing hard, tuning, or chasing more power. Its best-known weak point is VGT actuator/vane sticking, not the fuel system code (P1089) it's often confused with. The cleanest upgrade path is a calibrated drop-in like the True North Turbos 64/67 Drop-In Turbo for towing, or the 67/67 Drop-In Turbo for higher horsepower builds.
What is the L5P Duramax?
The L5P is GM's 6.6L V8 Duramax turbo-diesel, introduced for the 2017 model year in the Chevrolet Silverado 2500HD/3500HD and GMC Sierra 2500HD/3500HD. It replaced the LML (2011-2016) and remains the pickup-truck Duramax through the 2023 model year, before GM bumped output for 2024+.
L5D is a related but distinct engine code, not simply a California-emissions version of the L5P. It debuted for GM's medium-duty cab-and-chassis trucks (Silverado 4500HD/5500HD/6500HD) and runs a smaller turbo and different tune, rated lower than the L5P. Black Sheep's L5P/L5D turbo upgrades are grouped together because the core engine architecture and turbo mounting are shared, but they are not the same calibration or output.
Full platform background: What Is the L5P/L5D Duramax Turbo?
L5P Duramax years: what changed
| Years | Transmission | Horsepower / Torque | Notes |
|---|---|---|---|
| 2017-2019 | Allison 1000 6-speed | 445hp / 910 lb-ft | First-generation L5P; earliest units are the ones most discussed for VGT actuator and carbon-buildup complaints in owner forums |
| 2020 | Allison 10-speed | 445hp / 910 lb-ft | Transmission changed to the 10-speed; engine output unchanged |
| 2021-2023 | Allison 10-speed | 445hp / 910 lb-ft | Continued production with no major powertrain changes |
| 2024+ | Allison 10-speed | 470hp / 975 lb-ft | GM's most recent Duramax power bump; outside the scope of the L5P/L5D drop-in turbos covered on this page — check compatibility before ordering |
There's no single documented "bad year" the way there is on some earlier Duramax generations. The most consistent theme in owner reports is VGT actuator and vane-sticking complaints, which trend more common as mileage and carbon buildup accumulate rather than being tied to one specific model year.
L5P Duramax specs
| Spec | Value |
|---|---|
| Displacement | 6.6L (403 ci) V8 |
| Bore x Stroke | 95mm x 110mm |
| Compression Ratio | 16:1 |
| Horsepower / Torque | 445hp / 910 lb-ft (2017-2023); 470hp / 975 lb-ft (2024+) |
| Factory Turbo | BorgWarner variable-geometry turbo (VGT), ~28 psi peak boost |
| Fuel System | Common-rail direct injection, Denso HP4 pump, Denso GS4 injectors (up to 29,000 psi) |
| Firing Order | 1-2-7-8-4-5-6-3 (consistent with the rest of the Duramax family) |
| Oil Capacity | 10 quarts (9.5L) with filter |
| Transmission | Allison 1000 6-speed (2017-2019); Allison 10-speed (2020+) |
Common L5P Duramax problems
The L5P's best-documented weak point is the VGT actuator and vane mechanism. When the vane position sensor drifts or carbon builds up on the vanes, the ECM loses accurate feedback on vane position, which shows up as overboost, underboost, sluggish response, or a check-engine light. Full symptoms, causes, and fixes: L5P/L5D VGT Actuator & Turbo Problems and How to Prevent L5P/L5D VGT Sticking.
A note on P1089: this is one of the most-searched L5P codes, but it's a fuel rail pressure code, not a turbo code — it flags when fuel rail pressure deviates from spec during deceleration fuel cutoff, and it's typically caused by fuel contamination, a leaking injector, or a fuel pressure regulator issue. If you're chasing P1089, start with the fuel system, not the turbo.
How much power can the stock L5P turbo handle?
The factory VGT is a strong unit for a stock turbo, but it has a real airflow ceiling that shows up under towing loads, aggressive tuning, or added fueling. Where that ceiling is and what happens past it: L5P/L5D Duramax Turbo Power Limits.
Best L5P Duramax turbo upgrade paths
- Towing & daily driving — the 64/67 Drop-In Turbo prioritizes fast spool-up, strong low-end response, and lower EGTs under load.
- Higher horsepower & built trucks — the 67/67 Drop-In Turbo trades a bit of low-end for more top-end airflow and horsepower headroom, better suited to aggressive tuning and larger fueling upgrades.
- Rebuild instead of replace — if the factory core is sound, a billet compressor wheel rebuild can be the more cost-effective route.
- Supporting mods — get the most out of any turbo upgrade with the right supporting mods for towing and power.
- Emissions-legal builds in Canada — see Emissions-Legal Duramax Turbo Upgrades in Canada before planning a build that needs to stay compliant.
Tuning an L5P Duramax
Tuning changes boost targets, fueling, and shift behavior, but it doesn't change the physical airflow limit of the factory turbo — it just asks the stock unit to work harder against that ceiling. That's why aggressive tuning is one of the most common reasons owners start seeing VGT wear and rising EGTs sooner than expected, and why a turbo upgrade is usually the better foundation to tune around rather than a patch after the fact.
Where to buy
Browse the full L5P/L5D Duramax Drop-In Turbo Upgrades page or the Duramax L5P/L5D Turbochargers collection.
Related L5P Duramax resources
- What Is the L5P/L5D Duramax Turbo?
- L5P/L5D VGT Actuator & Turbo Problems
- L5P/L5D Duramax Turbo Power Limits
- L5P/L5D Billet Compressor Wheel & Rebuild Upgrades
- L5P/L5D Duramax Supporting Mods for Towing & Power
- How to Prevent L5P/L5D VGT Sticking
- Emissions-Legal Duramax Turbo Upgrades in Canada
- How to Lower EGTs on an L5P Duramax
- 67/67 vs 64/67 L5P Duramax Turbo
Frequently asked questions
What years is the L5P Duramax?
2017-2023 for the pickup-truck L5P. GM updated output to 470hp/975 lb-ft starting in 2024.
What's the difference between L5P and L5D?
They share the same core 6.6L Duramax architecture, but the L5D is GM's medium-duty variant (4500HD-6500HD chassis cabs) with a smaller turbo and a different, lower-output tune than the L5P found in 2500HD/3500HD pickups.
What is the most common L5P Duramax problem?
VGT actuator and vane sticking, usually from carbon buildup or a drifting vane position sensor, is the most consistently reported issue. P1089, despite being one of the most-searched L5P codes, is a fuel rail pressure code and unrelated to the turbo.
How much horsepower can a stock L5P turbo handle?
The factory turbo has real headroom but a real ceiling — see L5P/L5D Duramax Turbo Power Limits for the specifics before you tune past it.
Is the L5P Duramax reliable?
Yes, relative to earlier Duramax generations — there's no single "bad year" pattern. The turbo's VGT mechanism is the platform's best-known wear point, and it's a known, addressable issue rather than a fundamental design flaw.