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Honda J30A4 specs: 3.0L (182.9 ci) 6-cylinder, 86 x 86 mm (3.3858 x 3.3858 in) bore and stroke, 10:1 compression. Rated 240 hp, 2003–2005.
The Honda J30A4 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 6 cylinders displaces 30.5 ci (500 cc).
10:1 on aluminum heads is in the range that usually runs on pump premium; aluminum sheds heat faster than iron, which makes the same number a little more forgiving.
It is one of 30 engines in the J-series V6 family, sitting between the 152.6 ci and 223.6 ci members. 3 factory variants share these dimensions, rated at 240 hp across 2003–2005.
| Displacement | 182.9 ci / 3 L |
|---|---|
| Bore | 3.3858" |
| Stroke | 3.3858" |
| Cylinders | 6 |
| Configuration | V6 |
| Compression ratio | 10:1 |
| Bore/stroke ratio | 1 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | SOHC |
| Fuel type | gas |
| Advertised HP | 240 hp |
| Years | 2003–2005 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2003 | J30A4 net | 240 @ 6250 | 212 lb-ft @ 5000 | 10:1 |
| 2004 | J30A4 net | 240 @ 6250 | 212 lb-ft @ 5000 | 10:1 |
| 2005 | J30A4 net | 240 @ 6250 | 212 lb-ft @ 5000 | 10:1 |
Factory specification sheet.
| 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 |
| Static compression | 10:1 — in the range that usually runs on pump premium |
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 |
|---|---|---|
| 2003 | 240 hp | J30A4 |
| 2004 | 240 hp | J30A4 |
| 2005 | 240 hp | J30A4 |
1 factory vehicle, 2003–2007. Each year opens that model's engine table.