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Ford 46 4V Dohc Cobra specs: 281 ci (4.6L) 8-cylinder, 3.551 x 3.543 in (90.2 x 90 mm) bore and stroke, 9.85:1 compression. Rated 305 hp. DOHC.
The Ford 46 4V Dohc Cobra is close to square: 3.5512" bore against 3.5433" stroke, within 0.2%, which splits the difference between a high-revving layout and a torque layout. The 3.5433" stroke puts mean piston speed at 4,000 ft/min around 6,750 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 35.1 ci (576 cc).
9.85:1 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 16 engines in the Modular family, the smallest at 281 ci. Factory fitments include the Ford Mustang SVT Cobra, Ford Mustang Mach 1.
| Displacement | 281 ci / 4.6 L |
|---|---|
| Bore | 3.5512" |
| Stroke | 3.5433" |
| Cylinders | 8 |
| Compression ratio | 9.85:1 |
| Bore/stroke ratio | 1.002 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 305 hp |
| Bore/stroke character | 1.002 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,543 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 35.1 ci |
| Static compression | 9.85:1 — in the range that usually runs on pump premium |
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