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Chevrolet 402ci (2023) · 430 hp specs: 402 ci (6.6L) 8-cylinder, 4.065 x 3.858 in (103.3 x 98 mm) bore and stroke, 14:1 compression. Rated 430 hp, 2023. OHV.
The Chevrolet 402ci (2023) · 430 hp is oversquare — the 4.065" bore exceeds the 3.858" stroke by 5.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.858" stroke puts mean piston speed at 4,000 ft/min around 6,200 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.588 is in the range most production engines fall in. Each of the 8 cylinders displaces 50.3 ci (823 cc).
14:1 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 8 engines in the Chevrolet 402ci family, all of them 402 ci — the differences between them are in compression, heads and rating, not displacement.
| Displacement | 402 ci / 6.6 L |
|---|---|
| Bore | 4.065" |
| Stroke | 3.858" |
| Cylinders | 8 |
| Configuration | V8 |
| Compression ratio | 14:1 |
| Rod length | 6.125" |
| Rod ratio | 1.588 |
| Bore/stroke ratio | 1.054 |
| Piston deck clearance | 0" |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 430 hp |
| Years | 2023 |
| Bore/stroke character | 1.054 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,858 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.588 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 50.3 ci |
| Static compression | 14:1 — high enough that pump premium or better is normally required |
| Intake valve diameter | 2.135" |
|---|---|
| Exhaust valve diameter | 1.595" |
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