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Hyundai G4FJ specs: 1.6L (97.6 ci) 4-cylinder, 77 x 85.4 mm (3.0315 x 3.3622 in) bore and stroke, 9.5:1 compression. Rated 201 hp. Rod ratio and piston speed.
The Hyundai G4FJ is undersquare — the 3.3622" stroke exceeds the 3.0315" bore by 9.8% — a layout that trades peak RPM for leverage and torque low in the range. The 3.3622" stroke does not reach 4,000 ft/min of mean piston speed until about 7,150 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 24.4 ci (400 cc).
9.5:1 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 2 engines in the Gamma family, the largest at 97.6 ci. Factory fitments include the Kia K3 GT, Hyundai Veloster, Hyundai Kona and 6 others.
| Displacement | 97.6 ci / 1.6 L |
|---|---|
| Bore | 3.0315" |
| Stroke | 3.3622" |
| Cylinders | 4 |
| Compression ratio | 9.5:1 |
| Bore/stroke ratio | 0.902 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 201 hp |
| Bore/stroke character | 0.902 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,362 ft/min — conservative for a street engine |
| Displacement per cylinder | 24.4 ci |
| Static compression | 9.5:1 — in the range that usually runs on pump premium |
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