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Toyota 4GR-FSE specs: 2.5L (152.5 ci) 6-cylinder, 83 x 77 mm (3.2677 x 3.0315 in) bore and stroke, 12:1 compression. Rated 204 hp. Rod ratio and piston speed.
The Toyota 4GR-FSE is oversquare — the 3.2677" bore exceeds the 3.0315" stroke by 7.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.0315" stroke does not reach 4,000 ft/min of mean piston speed until about 7,900 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 25.4 ci (417 cc).
12:1 on aluminum heads is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.
It is one of 11 engines in the GR V6 family, the smallest at 152.5 ci. Factory fitments include the Lexus IS 250, Lexus GS 250, Toyota Crown.
| Displacement | 152.5 ci / 2.5 L |
|---|---|
| Bore | 3.2677" |
| Stroke | 3.0315" |
| Cylinders | 6 |
| Compression ratio | 12:1 |
| Bore/stroke ratio | 1.078 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 204 hp |
| Bore/stroke character | 1.078 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,032 ft/min — conservative for a street engine |
| Displacement per cylinder | 25.4 ci |
| Static compression | 12:1 — high enough that pump premium or better is normally required |
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