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Jeep 6-230 specs: 230 ci (3.7L) 6-cylinder, 3.339 x 4.374 in (84.8 x 111.1 mm) bore and stroke, 8.5:1 compression. Rated 140 hp. Rod ratio and piston speed.
The Jeep 6-230 is undersquare — the 4.374" stroke exceeds the 3.3386" bore by 23.7% — a layout that trades peak RPM for leverage and torque low in the range. With a 4.374" stroke, mean piston speed reaches 4,000 ft/min at only 5,500 RPM — the practical ceiling for a production bottom end — which is why a stroke this long makes its power low and runs out of safe revs early. Each of the 6 cylinders displaces 38.3 ci (628 cc).
8.5:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 4 engines in the Tornado family, all of them 230 ci — the differences between them are in compression, heads and rating, not displacement. Factory fitments include the Wagoneer, Gladiator, M715.
| Displacement | 230 ci / 3.7 L |
|---|---|
| Bore | 3.3386" |
| Stroke | 4.374" |
| Cylinders | 6 |
| Compression ratio | 8.5:1 |
| Bore/stroke ratio | 0.763 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 140 hp |
| Bore/stroke character | 0.763 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,374 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 38.3 ci |
| Static compression | 8.5:1 — low by modern standards, generally happy on regular pump fuel |
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