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Chevrolet L5P specs: 403 ci (6.6L) 8-cylinder, 4.055 x 3.898 in (103 x 99 mm) bore and stroke. Rated 445-470 hp, 2017–2026.
The Chevrolet Duramax (L5P) is close to square: 4.0551" bore against 3.8976" stroke, within 4.0%, which splits the difference between a high-revving layout and a torque layout. The 3.8976" stroke puts mean piston speed at 4,000 ft/min around 6,150 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 50.4 ci (825 cc).
It is one of 13 engines in the Duramax family, the largest at 403 ci. 10 factory variants share these dimensions, rated from 445 to 470 hp across 2017–2026.
| Displacement | 403 ci / 6.6 L |
|---|---|
| Bore | 4.0551" |
| Stroke | 3.8976" |
| Cylinders | 8 |
| Configuration | V8 |
| Bore/stroke ratio | 1.04 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | OHV |
| Fuel type | diesel |
| Advertised HP | 445–470 hp |
| Years | 2017–2026 |
| Bore/stroke character | 1.040 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,898 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 50.4 ci |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 2017 | 445 hp | L5P |
| 2018 | 445 hp | L5P |
| 2019 | 445 hp | L5P |
| 2020 | 445 hp | L5P |
| 2021 | 445 hp | L5P |
| 2022 | 445 hp | L5P |
| 2023 | 445 hp | L5P |
| 2024 | 470 hp | L5P |
| 2025 | 470 hp | L5P |
| 2026 | 470 hp | L5P |