See other engines in this family
GMC 250 specs: 250 ci (4.1L) 6-cylinder, 3.875 x 3.53 in (98.4 x 89.7 mm) bore and stroke, 8.5:1 compression. Rated 155 hp. OHV. Rod ratio and piston speed.
The GMC Chevy Straight-6 (194/230/250/292) (250) is oversquare — the 3.875" bore exceeds the 3.53" stroke by 9.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.53" stroke puts mean piston speed at 4,000 ft/min around 6,800 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 41.7 ci (683 cc).
8.5:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 10 engines in the Chevy Straight-6 (194/230/250/292) family, sitting between the 194 ci and 292 ci members. Factory fitments include the Chevrolet Chevelle, Chevrolet Camaro, Chevrolet Nova and 2 others.
| Displacement | 250 ci / 4.1 L |
|---|---|
| Bore | 3.875" |
| Stroke | 3.53" |
| Cylinders | 6 |
| Compression ratio | 8.5:1 |
| Bore/stroke ratio | 1.098 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 155 hp |
| Bore/stroke character | 1.098 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,530 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 41.7 ci |
| Static compression | 8.5:1 — low by modern standards, generally happy on regular pump fuel |
Each link opens the calculator with this engine's specs already filled in.