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Chevrolet LT6 specs: 333 ci (5.5L) 8-cylinder, 4.104 x 3.15 in (104.2 x 80 mm) bore and stroke, 12.5:1 compression. Rated 670 hp, 2023–2026.
The Chevrolet 333ci (LT6) is oversquare — the 4.1043" bore exceeds the 3.1496" stroke by 30.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.1496" stroke does not reach 4,000 ft/min of mean piston speed until about 7,600 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 41.6 ci (682 cc).
12.5:1 on aluminum heads is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.
It is one of 2 engines in the Chevrolet 333ci family, all of them 333 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated at 670 hp across 2023–2026.
| Displacement | 333 ci / 5.5 L |
|---|---|
| Bore | 4.1043" |
| Stroke | 3.1496" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 12.5:1 |
| Bore/stroke ratio | 1.303 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Induction | direct injection |
| Fuel type | gas |
| Advertised HP | 670 hp |
| Years | 2023–2026 |
| Bore/stroke character | 1.303 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,150 ft/min — conservative for a street engine |
| Displacement per cylinder | 41.6 ci |
| Static compression | 12.5:1 — high enough that pump premium or better is normally required |
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 |
|---|---|---|
| 2023 | 670 hp | LT6 |
| 2024 | 670 hp | LT6 |
| 2025 | 670 hp | LT6 |
| 2026 | 670 hp | LT6 |