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Chevrolet 302ci specs: 302 ci (4.9L) 8-cylinder, 4.00 x 3.00 in (101.6 x 76.2 mm) bore and stroke, 12.5:1 compression. Rated 350-360 hp, 2018–2023. OHV.
The Chevrolet 302ci is oversquare — the 4" bore exceeds the 3" stroke by 33.3% — a layout that favors airflow and RPM over leverage at the crank. The 3" stroke does not reach 4,000 ft/min of mean piston speed until about 8,000 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 2.187 is long by production standards — less side-load on the cylinder wall and gentler piston acceleration around TDC, the geometry that tolerates high RPM. Each of the 8 cylinders displaces 37.8 ci (619 cc).
12.5:1 on iron heads is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.
It is one of 2 engines in the Chevrolet 302ci family, all of them 302 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated from 350 to 360 hp across 2018–2023.
| Displacement | 302 ci / 4.9 L |
|---|---|
| Bore | 4" |
| Stroke | 3" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 12.5:1 |
| Rod length | 6.56" |
| Rod ratio | 2.187 |
| Bore/stroke ratio | 1.333 |
| Piston deck clearance | 0.01" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 350–360 hp |
| Years | 2018–2023 |
| Bore/stroke character | 1.333 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,000 ft/min — conservative for a street engine |
| Rod ratio | 2.187 — long — less side loading on the cylinder wall, favours high RPM |
| Displacement per cylinder | 37.8 ci |
| Static compression | 12.5:1 — high enough that pump premium or better is normally required |
| Intake valve diameter | 2.135" |
|---|---|
| Exhaust valve diameter | 1.595" |
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 |
|---|---|---|
| 2018 | 360 hp | — |
| 2019 | 360 hp | — |
| 2022 | 350 hp | — |
| 2023 | 350 hp | — |