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GMC L26 specs: 200 ci (3.3L) 6-cylinder, 3.50 x 3.48 in (88.9 x 88.4 mm) bore and stroke, 8.2:1 compression. Built 1978–1979.
The GMC 200ci (L26) is close to square: 3.5" bore against 3.48" stroke, within 0.6%, which splits the difference between a high-revving layout and a torque layout. The 3.48" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 33.3 ci (546 cc).
8.2:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
2 factory variants share these dimensions across 1978–1979.
| Displacement | 200 ci / 3.3 L |
|---|---|
| Bore | 3.5" |
| Stroke | 3.48" |
| Cylinders | 6 |
| Configuration | V6 |
| Compression ratio | 8.2:1 |
| Bore/stroke ratio | 1.006 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Firing order | 1-6-5-4-3-2 |
| Years | 1978–1979 |
| Bore/stroke character | 1.006 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,480 ft/min — conservative for a street engine |
| Displacement per cylinder | 33.3 ci |
| Static compression | 8.2:1 — low by modern standards, generally happy on regular pump fuel |
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 |
|---|---|---|
| 1978 | — | L26 |
| 1979 | — | L26 |
4 factory vehicles, 1978–1979. Each year opens that model's engine table.