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Hyundai D4FA specs: 1.5L (91.5 ci) 4-cylinder, 75 x 84.5 mm (2.9528 x 3.3268 in) bore and stroke, 17.8:1 compression. Rated 110 hp. DOHC.
The Hyundai D4FA is undersquare — the 3.3268" stroke exceeds the 2.9528" bore by 11.2% — a layout that trades peak RPM for leverage and torque low in the range. The 3.3268" stroke does not reach 4,000 ft/min of mean piston speed until about 7,200 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 22.9 ci (375 cc).
At 17.8:1 this is a compression-ignition engine: the ratio is the heat source that lights the fuel, not a knock limit to be managed.
It is one of 2 engines in the U family, the smallest at 91.5 ci. Factory fitments include the Hyundai Getz, Hyundai Accent, Kia Rio.
| Displacement | 91.5 ci / 1.5 L |
|---|---|
| Bore | 2.9528" |
| Stroke | 3.3268" |
| Cylinders | 4 |
| Compression ratio | 17.8:1 |
| Bore/stroke ratio | 0.888 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | diesel |
| Advertised HP | 110 hp |
| Bore/stroke character | 0.888 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,327 ft/min — conservative for a street engine |
| Displacement per cylinder | 22.9 ci |
| Static compression | 17.8:1 — high enough that pump premium or better is normally required |
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