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Porsche M48.50 specs: 4.5L (275 ci) 8-cylinder, 93 x 83 mm (3.6614 x 3.2677 in) bore and stroke, 9.5:1 compression. Rated 450 hp, 2003–2006.
The Porsche M48.50 is oversquare — the 3.6614" bore exceeds the 3.2677" stroke by 12.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.2677" stroke does not reach 4,000 ft/min of mean piston speed until about 7,350 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 34.4 ci (563 cc).
9.5:1 is in the range that usually runs on pump premium.
It is one of 2 engines in the Porsche 275ci family, all of them 275 ci — the differences between them are in compression, heads and rating, not displacement. 5 factory variants share these dimensions, rated at 450 hp across 2003–2006.
| Displacement | 275 ci / 4.5 L |
|---|---|
| Bore | 3.6614" |
| Stroke | 3.2677" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 9.5:1 * |
| Bore/stroke ratio | 1.12 |
* Compression ratio from a single source; not yet cross-verified.
| Fuel type | gas |
|---|---|
| Advertised HP | 450 hp |
| Years | 2003–2006 |
| Bore/stroke character | 1.120 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,268 ft/min — conservative for a street engine |
| Displacement per cylinder | 34.4 ci |
| Static compression | 9.5:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| 2003 | 450 hp | M48.50 |
| 2004 | 450 hp | M48.50 |
| 2005 | 450 hp | M48.50 |
| 2006 | — | M48.50 |
| 2006 | 450 hp | M48.50 |
1 factory vehicle, 2003–2006. Each year opens that model's engine table.