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Oldsmobile LT6 specs: 262 ci (4.3L) 6-cylinder, 3.80 x 3.86 in (96.5 x 98 mm) bore and stroke, 21.6:1 compression. Rated 85 hp. Rod ratio and piston speed.
The Oldsmobile Diesel (LT6) is close to square: 3.8" bore against 3.86" stroke, within 1.6%, which splits the difference between a high-revving layout and a torque layout. The 3.86" stroke puts mean piston speed at 4,000 ft/min around 6,200 RPM, which is where a production bottom end is generally considered at its limit. Each of the 6 cylinders displaces 43.7 ci (716 cc).
At 21.6:1 this is a compression-ignition engine: the ratio is the heat source that lights the fuel, not a knock limit to be managed.
It is one of 5 engines in the Diesel family, the largest at 262 ci. Factory fitments include the Oldsmobile Cutlass Ciera, Oldsmobile Delta 88, Cutlass Ciera and 1 other.
| Displacement | 262 ci / 4.3 L |
|---|---|
| Bore | 3.8" |
| Stroke | 3.86" |
| Cylinders | 6 |
| Compression ratio | 21.6:1 |
| Bore/stroke ratio | 0.984 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | diesel |
| Advertised HP | 85 hp |
| Bore/stroke character | 0.984 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,860 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 43.7 ci |
| Static compression | 21.6:1 — high enough that pump premium or better is normally required |
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