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Ford Mazda RF specs: 121.9 ci (2.0L) 4-cylinder, 3.386 x 3.386 in (86 x 86 mm) bore and stroke. Rod ratio and piston speed worked out.
The Ford Mazda RF is exactly square — 3.3858" bore and 3.3858" stroke are the same — which splits the difference between a high-revving layout and a torque layout. The 3.3858" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 30.5 ci (499 cc).
It is one of 5 engines in the Mazda-built Fours family, the largest at 121.9 ci.
| Displacement | 121.9 ci / 2 L |
|---|---|
| Bore | 3.3858" |
| Stroke | 3.3858" |
| Cylinders | 4 |
| Bore/stroke ratio | 1 |
| Fuel type | diesel |
|---|
| Bore/stroke character | 1.000 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,386 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.5 ci |
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