Oldsmobile 303ci 7.5:1 Specs
Oldsmobile Oldsmobile 303ci · 3.75" × 3.438" · 7.5:1 engine specs: 303 ci (5L), 8-cylinder, 3.75" bore x 3.438" stroke, 7.5:1 compression.
Dimensions
| Displacement | 303 ci / 5 L |
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| Bore | 3.75" |
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| Stroke | 3.438" |
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| Cylinders | 8 |
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| Compression ratio | 7.5:1 |
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| Rod length | 6.625" |
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| Rod ratio | 1.927 |
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| Bore/stroke ratio | 1.091 |
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Construction
| Induction | 1-2 |
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| Advertised HP | 145–160 hp |
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| Years | 1952 |
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What these numbers mean
| Bore/stroke character | 1.091 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
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| Mean piston speed at 6,000 RPM | 3,438 ft/min — conservative for a street engine |
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| Rod ratio | 1.927 — long — less side loading on the cylinder wall, favours high RPM |
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| Displacement per cylinder | 37.9 ci |
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| Static compression | 7.5:1 — low by modern standards, generally happy on regular pump fuel |
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Cylinder head
| Chamber volume | 95.48 cc |
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| Rocker ratio | 1.8:1 |
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| Lifter type | hydraulic |
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Variants sharing these dimensions (2)
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
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| 1952 | 145 hp | — |
| 1952 | 160 hp | — |
Similar engines
Source: NHRA blueprints — nhra.net blueprints
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