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Mercedes-Benz M113 E43 specs: 4.3L (262.4 ci) 8-cylinder, 89.9 x 84 mm (3.5394 x 3.3071 in) bore and stroke, 10:1 compression. Rated 275 hp. SOHC.
The Mercedes-Benz M113 E43 is oversquare — the 3.5394" bore exceeds the 3.3071" stroke by 7.0% — a layout that favors airflow and RPM over leverage at the crank. The 3.3071" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 8 cylinders displaces 32.8 ci (537 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 4 engines in the M113 family, the smallest at 262.4 ci. Factory fitments include the Mercedes-Benz C43 AMG, Mercedes-Benz E430, Mercedes-Benz CLK430 and 2 others.
| Displacement | 262.4 ci / 4.3 L |
|---|---|
| Bore | 3.5394" |
| Stroke | 3.3071" |
| Cylinders | 8 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1.07 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 275 hp |
| Bore/stroke character | 1.070 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,307 ft/min — conservative for a street engine |
| Displacement per cylinder | 32.8 ci |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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