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Dodge 318ci (1960–1991) specs: 318 ci (5.2L) 8-cylinder, 3.909 x 3.311 in (99.3 x 84.1 mm) bore and stroke. Rated 135-260 hp, 1960–1991.
The Dodge 318ci (1960–1991) is oversquare — the 3.9094" bore exceeds the 3.311" stroke by 18.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.311" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.849 is long by production standards — less side-load on the cylinder wall and gentler piston acceleration around TDC, the geometry that tolerates high RPM. Each of the 8 cylinders displaces 39.8 ci (651 cc).
It is one of 15 engines in the Dodge 318ci family, all of them 318 ci — the differences between them are in compression, heads and rating, not displacement. 50 factory variants share these dimensions, rated from 135 to 260 hp across 1960–1991.
| Displacement | 318 ci / 5.2 L |
|---|---|
| Bore | 3.9094" |
| Stroke | 3.311" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 8.6–9.2:1 (published figures vary) |
| Rod length | 6.123" |
| Rod ratio | 1.849 |
| Bore/stroke ratio | 1.181 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 135–260 hp |
| Years | 1960–1991 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. | Duration int / exh | Valve lift int / exh | LSA |
|---|---|---|---|---|---|---|---|
| 1960 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9:1 | — | — | — |
| 1961 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9:1 | — | — | — |
| 1961 | gross | 260 | — | 9:1 | — | — | — |
| 1962 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9:1 | — | — | — |
| 1962 | gross | 260 @ 4400 | 345 lb-ft @ 2800 | 9:1 | — | — | — |
| 1963 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9:1 | — | — | — |
| 1964 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9:1 | — | — | — |
| 1965 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9:1 | 244° / 240° | 0.397" / 0.403" | 111° |
| 1967 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9.2:1 | 244° | 0.390" | 111° |
| 1968 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9.2:1 | 240° / 248° | 0.373" / 0.399" | 112° |
| 1969 | gross | 230 @ 4400 | 340 lb-ft @ 2400 | 9.2:1 | 240° / 248° | 0.372" / 0.400" | 112° |
| 1971 | gross | 230 @ 4400 | 320 lb-ft @ 2000 | 8.6:1 | — | — | — |
| 1972 | net | 150 @ 4000 | 260 lb-ft @ 1600 | 8.6:1 | 240° / 248° | 0.373" / 0.399" | 109° |
| 1977 | net | 145 @ 4000 | — | — | — | — | — |
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 | 1.181 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,311 ft/min — conservative for a street engine |
| Rod ratio | 1.849 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 39.8 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 |
|---|---|---|
| 1960 | 230 hp | — |
| 1960 | 255 hp | — |
| 1961 | 230 hp | — |
| 1961 | 260 hp | — |
| 1962 | 200 hp | — |
| 1962 | 230 hp | — |
| 1962 | 260 hp | — |
| 1963 | 200 hp | — |
| 1963 | 230 hp | — |
| 1964 | 200 hp | — |
| 1964 | 230 hp | — |
| 1965 | 200 hp | — |
| 1965 | 230 hp | — |
| 1966 | 200 hp | — |
| 1966 | 230 hp | — |
| 1967 | 210 hp | — |
| 1967 | 230 hp | — |
| 1968 | — | — |
| 1968 | 230 hp | — |
| 1969 | — | — |
| 1969 | 230 hp | — |
| 1970 | — | — |
| 1970 | 210 hp | — |
| 1970 | 230 hp | — |
| 1971 | — | — |
| 1971 | 210 hp | — |
| 1971 | 230 hp | — |
| 1972 | — | — |
| 1972 | 150 hp | — |
| 1973 | — | — |
| 1973 | 150 hp | — |
| 1974 | 150 hp | — |
| 1975 | 145 hp | — |
| 1975 | 150 hp | — |
| 1976 | — | — |
| 1976 | 150 hp | — |
| 1977 | — | — |
| 1977 | 145 hp | — |
| 1977 | 150 hp | — |
| 1978 | — | — |
| 1978 | 150 hp | — |
| 1979 | — | — |
| 1979 | 150 hp | — |
| 1980 | — | — |
| 1980 | 135 hp | — |
| 1981 | — | — |
| 1988 | — | — |
| 1989 | — | — |
| 1990 | — | — |
| 1991 | — | — |
11 factory vehicles, 1960–1991. Each year opens that model's engine table.