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Lexus 1LR-GSE specs: 4.8L (292.9 ci) 10-cylinder, 88 x 79 mm (3.4646 x 3.1102 in) bore and stroke, 12:1 compression. Rated 552 hp. Rod ratio and piston speed.
The Lexus 1LR-GSE is oversquare — the 3.4646" bore exceeds the 3.1102" stroke by 11.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.1102" stroke does not reach 4,000 ft/min of mean piston speed until about 7,700 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 10 cylinders displaces 29.3 ci (480 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 2 engines in the LR family, the smallest at 292.9 ci. Factory fitments include the Lexus LFA.
| Displacement | 292.9 ci / 4.8 L |
|---|---|
| Bore | 3.4646" |
| Stroke | 3.1102" |
| Cylinders | 10 |
| Compression ratio | 12:1 |
| Bore/stroke ratio | 1.114 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 552 hp |
| Bore/stroke character | 1.114 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,110 ft/min — conservative for a street engine |
| Displacement per cylinder | 29.3 ci |
| Static compression | 12:1 — high enough that pump premium or better is normally required |
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