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Chevrolet Duramax 7800 specs: 476 ci (7.8L) 6-cylinder, 4.528 x 4.921 in (115 x 125 mm) bore and stroke. Built 2003–2009.
The Chevrolet Duramax 7800 is undersquare — the 4.9213" stroke exceeds the 4.5276" bore by 8.0% — a layout that trades peak RPM for leverage and torque low in the range. With a 4.9213" stroke, mean piston speed reaches 4,000 ft/min at only 4,900 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 79.3 ci (1,300 cc).
7 factory variants share these dimensions across 2003–2009.
| Displacement | 476 ci / 7.8 L |
|---|---|
| Bore | 4.5276" |
| Stroke | 4.9213" |
| Cylinders | 6 |
| Configuration | I6 |
| Bore/stroke ratio | 0.92 |
| Fuel type | diesel |
|---|---|
| Years | 2003–2009 |
| Bore/stroke character | 0.920 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 4,921 ft/min — above the 4,500 ft/min mark where most production bottom ends are considered at their limit |
| Displacement per cylinder | 79.3 ci |
Each link opens the calculator with this engine's specs already filled in.
These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.
| Year | Advertised HP | Code |
|---|---|---|
| 2003 | — | Duramax 7800 |
| 2004 | — | Duramax 7800 |
| 2005 | — | Duramax 7800 |
| 2006 | — | Duramax 7800 |
| 2007 | — | Duramax 7800 |
| 2008 | — | Duramax 7800 |
| 2009 | — | Duramax 7800 |
1 factory vehicle, 2003–2009. Each year opens that model's engine table.