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Chevrolet LY5 specs: 98 ci (1.6L) 4-cylinder, 3.11 x 3.209 in (79 x 81.5 mm) bore and stroke. Rated 60-63 hp, 1976–1978. Used in the Chevrolet Chevette. DOHC.
The Chevrolet Ecotec (LY5) is close to square: 3.1102" bore against 3.2087" stroke, within 3.1%, which splits the difference between a high-revving layout and a torque layout. The 3.2087" stroke does not reach 4,000 ft/min of mean piston speed until about 7,500 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 4 cylinders displaces 24.5 ci (401 cc).
It is one of 20 engines in the Ecotec family, sitting between the 61 ci and 150 ci members. 3 factory variants share these dimensions, rated from 60 to 63 hp across 1976–1978.
| Displacement | 98 ci / 1.6 L |
|---|---|
| Bore | 3.1102" |
| Stroke | 3.2087" |
| Cylinders | 4 |
| Configuration | I4 |
| Bore/stroke ratio | 0.969 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Advertised HP | 60–63 hp |
| Years | 1976–1978 |
| Bore/stroke character | 0.969 — square — bore and stroke are within 5%, a balanced compromise |
|---|---|
| Mean piston speed at 6,000 RPM | 3,209 ft/min — conservative for a street engine |
| Displacement per cylinder | 24.5 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 |
|---|---|---|
| 1976 | 60 hp | LY5 |
| 1977 | 63 hp | LY5 |
| 1978 | 63 hp | LY5 |