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Chevrolet Z09 package specs: 122 ci (2.0L) 4-cylinder, 3.386 x 3.386 in (86 x 86 mm) bore and stroke. Rated 110 hp, 1975–1976. Used in the Chevrolet Vega.
The Chevrolet Z09 package is exactly square — 3.3858" bore and 3.3858" stroke are the same — which splits the difference between a high-revving layout and a torque layout. The 3.3858" 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 4 cylinders displaces 30.5 ci (500 cc).
It is one of 20 engines in the Ecotec family, sitting between the 61 ci and 150 ci members. 2 factory variants share these dimensions, rated at 110 hp across 1975–1976.
| Displacement | 122 ci / 2 L |
|---|---|
| Bore | 3.3858" |
| Stroke | 3.3858" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 1 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 110 hp |
| Years | 1975–1976 |
| Bore/stroke character | 1.000 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,386 ft/min — conservative for a street engine |
| Displacement per cylinder | 30.5 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 |
|---|---|---|
| 1975 | 110 hp | Z09 package |
| 1976 | 110 hp | Z09 package |