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Lexus A25A-FKS specs: 2.5L (152 ci) 4-cylinder, 87.5 x 103.4 mm (3.4449 x 4.0709 in) bore and stroke, 13:1 compression. Rated 203 hp. DOHC.
The Lexus A25A-FKS is undersquare — the 4.0709" stroke exceeds the 3.4449" bore by 15.4% — a layout that trades peak RPM for leverage and torque low in the range. The 4.0709" stroke puts mean piston speed at 4,000 ft/min around 5,900 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 38.0 ci (623 cc).
13:1 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 15 engines in the Dynamic Force family, sitting between the 121.9 ci and 210 ci members. Factory fitments include the Lexus ES 250, Lexus RX 350, Lexus IS 300 and 6 others.
| Displacement | 152 ci / 2.5 L |
|---|---|
| Bore | 3.4449" |
| Stroke | 4.0709" |
| Cylinders | 4 |
| Compression ratio | 13:1 |
| Bore/stroke ratio | 0.846 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 203 hp |
| Bore/stroke character | 0.846 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,071 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 38.0 ci |
| Static compression | 13:1 — high enough that pump premium or better is normally required |
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