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Chevrolet LS9 specs: 350 ci (5.7L) 8-cylinder, 4.001 x 3.484 in (101.6 x 88.5 mm) bore and stroke. Rated 155-255 hp, 1969–1986.
The Chevrolet 350ci (LS9) is oversquare — the 4.001" bore exceeds the 3.484" stroke by 14.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.484" 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. A rod ratio of 1.636 is in the range most production engines fall in. Each of the 8 cylinders displaces 43.8 ci (717 cc).
It is one of 34 engines in the Chevrolet 350ci family, all of them 350 ci — the differences between them are in compression, heads and rating, not displacement. 20 factory variants share these dimensions, rated from 155 to 255 hp across 1969–1986.
| Displacement | 350 ci / 5.7 L |
|---|---|
| Bore | 4.001" |
| Stroke | 3.484" |
| Cylinders | 8 |
| Configuration | V8 |
| Rod length | 5.7" |
| Rod ratio | 1.636 |
| Bore/stroke ratio | 1.148 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 155–255 hp |
| Years | 1969–1986 |
| Bore/stroke character | 1.148 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,484 ft/min — conservative for a street engine |
| Rod ratio | 1.636 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 43.8 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 |
|---|---|---|
| 1969 | 255 hp | LS9 |
| 1970 | 255 hp | LS9 |
| 1971 | 250 hp | LS9 |
| 1973 | 155 hp | LS9 |
| 1975 | 160 hp | LS9 |
| 1976 | 165 hp | LS9 |
| 1977 | 165 hp | LS9 |
| 1978 | — | LS9 |
| 1978 | 165 hp | LS9 |
| 1979 | — | LS9 |
| 1979 | 165 hp | LS9 |
| 1980 | 170 hp | LS9 |
| 1980 | 175 hp | LS9 |
| 1981 | — | LS9 |
| 1982 | 160 hp | LS9 |
| 1982 | 165 hp | LS9 |
| 1983 | 165 hp | LS9 |
| 1984 | 165 hp | LS9 |
| 1985 | 165 hp | LS9 |
| 1986 | 165 hp | LS9 |