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Chrysler FirePower V-8 specs: 331 ci 8-cylinder, 3.813 x 3.625 in (96.8 x 92.1 mm) bore and stroke, 8.5:1 compression. Rated 180-250 hp, 1951–1955.
The Chrysler FirePower V-8 is oversquare — the 3.8125" bore exceeds the 3.625" stroke by 5.2% — a layout that favors airflow and RPM over leverage at the crank. The 3.625" stroke puts mean piston speed at 4,000 ft/min around 6,600 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 41.4 ci (678 cc).
8.5:1 is low by modern standards and generally happy on regular pump fuel.
It is one of 2 engines in the Chrysler 331ci family, all of them 331 ci — the differences between them are in compression, heads and rating, not displacement. 6 factory variants share these dimensions, rated from 180 to 250 hp across 1951–1955.
| Displacement | 331 ci |
|---|---|
| Bore | 3.8125" |
| Stroke | 3.625" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.5:1 |
| Bore/stroke ratio | 1.052 |
| Fuel type | gas |
|---|---|
| Advertised HP | 180–250 hp |
| Years | 1951–1955 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1955 | gross | 250 @ 4600 | — | 8.5:1 | — | 0.375" / 0.361" | — |
Factory specification sheet. Durations are the factory's advertised figures at the basis printed on the sheet, not duration at .050" lift; lobe separation is calculated from the printed valve timing.
| Bore/stroke character | 1.052 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,625 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 41.4 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.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 1951 | 180 hp | FirePower V-8 |
| 1952 | 180 hp | FirePower V-8 |
| 1953 | 180 hp | FirePower V-8 |
| 1954 | 195 hp | FirePower V-8 |
| 1954 | 235 hp | FirePower V-8 |
| 1955 | 250 hp | FirePower V-8 |
2 factory vehicles, 1951–1955. Each year opens that model's engine table.