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Pontiac 455 specs: 455 ci (7.5L) 8-cylinder, 4.189 x 4.063 in (106.4 x 103.2 mm) bore and stroke, 8:1 compression. Rated 325 hp. Rod ratio and piston speed.
The Pontiac V8 (455) is close to square: 4.189" bore against 4.063" stroke, within 3.1%, which splits the difference between a high-revving layout and a torque layout. The 4.063" stroke puts mean piston speed at 4,000 ft/min around 5,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 56.9 ci (932 cc).
8:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 13 engines in the Pontiac V8 family, the largest at 455 ci. Factory fitments include the Pontiac Firebird Trans Am, Pontiac GTO, Pontiac Grand Ville.
| Displacement | 455 ci / 7.5 L |
|---|---|
| Bore | 4.189" |
| Stroke | 4.063" |
| Cylinders | 8 |
| Compression ratio | 8:1 |
| Bore/stroke ratio | 1.031 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 325 hp |
| Bore/stroke character | 1.031 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 4,063 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 56.9 ci |
| Static compression | 8:1 — low by modern standards, generally happy on regular pump fuel |
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