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GMC LY7 specs: 217 ci (3.6L) 6-cylinder, 3.701 x 3.37 in (94 x 85.6 mm) bore and stroke. Rated 275 hp, 2007–2008. Used in the Cadillac CTS and GMC Acadia.
The GMC 217ci (LY7) is oversquare — the 3.7008" bore exceeds the 3.3701" stroke by 9.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.3701" stroke does not reach 4,000 ft/min of mean piston speed until about 7,100 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 36.2 ci (593 cc).
It is one of 3 engines in the GMC 217ci family, all of them 217 ci — the differences between them are in compression, heads and rating, not displacement. 2 factory variants share these dimensions, rated at 275 hp across 2007–2008.
| Displacement | 217 ci / 3.6 L |
|---|---|
| Bore | 3.7008" |
| Stroke | 3.3701" |
| Cylinders | 6 |
| Configuration | V6 |
| Bore/stroke ratio | 1.098 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 275 hp |
| Years | 2007–2008 |
| Bore/stroke character | 1.098 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,370 ft/min — conservative for a street engine |
| Displacement per cylinder | 36.2 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 |
|---|---|---|
| 2007 | 275 hp | LY7 |
| 2008 | 275 hp | LY7 |
6 factory vehicles, 2004–2012. Each year opens that model's engine table.