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Chevrolet LWQ specs: 170 ci (2.8L) 4-cylinder, 3.622 x 4.134 in (92 x 105 mm) bore and stroke, 16.5:1 compression. Rated 181 hp. Rod ratio and piston speed.
The Chevrolet Duramax (LWQ) is undersquare — the 4.1339" stroke exceeds the 3.622" bore by 12.4% — a layout that trades peak RPM for leverage and torque low in the range. The 4.1339" stroke puts mean piston speed at 4,000 ft/min around 5,800 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 42.5 ci (696 cc).
At 16.5:1 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 13 engines in the Duramax family, the smallest at 170 ci. Factory fitments include the Chevrolet Colorado, GMC Canyon.
| Displacement | 170 ci / 2.8 L |
|---|---|
| Bore | 3.622" |
| Stroke | 4.1339" |
| Cylinders | 4 |
| Compression ratio | 16.5:1 |
| Bore/stroke ratio | 0.876 |
| Block material | cast iron |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | diesel |
| Advertised HP | 181 hp |
| Bore/stroke character | 0.876 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,134 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 42.5 ci |
| Static compression | 16.5:1 — high enough that pump premium or better is normally required |
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