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Toyota F specs: 3.9L (236.7 ci) 6-cylinder, 90 x 101.6 mm (3.5433 x 4.0000 in) bore and stroke. OHV. Rod ratio and piston speed worked out.
The Toyota F-series (F) is undersquare — the 4" stroke exceeds the 3.5433" bore by 11.4% — a layout that trades peak RPM for leverage and torque low in the range. The 4" stroke puts mean piston speed at 4,000 ft/min around 6,000 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 39.4 ci (646 cc).
It is one of 11 engines in the F-series family, the smallest at 236.7 ci.
| Displacement | 236.7 ci / 3.9 L |
|---|---|
| Bore | 3.5433" |
| Stroke | 4" |
| Cylinders | 6 |
| Bore/stroke ratio | 0.886 |
| Valvetrain | OHV |
|---|---|
| Fuel type | gas |
| Bore/stroke character | 0.886 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,000 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 39.4 ci |
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