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Mazda Renesis 13B MSP specs: 1.308L (79.8 ci) 2-cylinder, 105 x 80 mm (4.1339 x 3.1496 in) bore and stroke, 10:1 compression. Rated 232 hp. Rotary.
The Mazda Renesis 13B MSP is oversquare — the 4.1339" bore exceeds the 3.1496" stroke by 31.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.1496" stroke does not reach 4,000 ft/min of mean piston speed until about 7,600 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 2 cylinders displaces 39.9 ci (654 cc).
10:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 14 engines in the Rotary family, sitting between the 59.9 ci and 119.7 ci members. Factory fitments include the Mazda RX-8.
| Displacement | 79.8 ci / 1.308 L |
|---|---|
| Bore | 4.1339" |
| Stroke | 3.1496" |
| Cylinders | 2 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1.313 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | Rotary |
| Fuel type | gas |
| Advertised HP | 232 hp |
| Bore/stroke character | 1.313 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,150 ft/min — conservative for a street engine |
| Displacement per cylinder | 39.9 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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