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GMC L65 specs: 395 ci (6.5L) 8-cylinder, 4.06 x 3.82 in (103.1 x 97 mm) bore and stroke, 21.5:1 compression. Rated 195 hp, 1997–2000.
The GMC 395ci (L65) is oversquare — the 4.06" bore exceeds the 3.82" stroke by 6.3% — a layout that favors airflow and RPM over leverage at the crank. The 3.82" stroke puts mean piston speed at 4,000 ft/min around 6,300 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 49.4 ci (809 cc).
At 21.5:1 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 4 engines in the GMC 395ci family, all of them 395 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated at 195 hp across 1997–2000.
| Displacement | 395 ci / 6.5 L |
|---|---|
| Bore | 4.06" |
| Stroke | 3.82" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 21.5:1 |
| Bore/stroke ratio | 1.063 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | diesel |
| Firing order | 1-8-7-2-6-5-4-3 |
| Advertised HP | 195 hp |
| Years | 1997–2000 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 1999 | L65 net | 195 @ 3400 | 430 lb-ft @ 1800 | — |
Factory specification sheet.
| Bore/stroke character | 1.063 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,820 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 49.4 ci |
| Static compression | 21.5:1 — high enough that pump premium or better is normally required |
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 |
|---|---|---|
| 1997 | — | L65 |
| 1999 | — | L65 |
| 1999 | 195 hp | L65 |
| 2000 | 195 hp | L65 |
4 factory vehicles, 1994–2002. Each year opens that model's engine table.