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Mazda MZR 2.3 specs: 2.261L (138 ci) 4-cylinder, 87.5 x 94 mm (3.4449 x 3.7008 in) bore and stroke, 9.7:1 compression. Rated 160 hp, 2004–2009.
The Mazda MZR 2.3 is undersquare — the 3.7008" stroke exceeds the 3.4449" bore by 6.9% — a layout that trades peak RPM for leverage and torque low in the range. The 3.7008" stroke puts mean piston speed at 4,000 ft/min around 6,500 RPM, which is where a production bottom end is generally considered at its limit. Each of the 4 cylinders displaces 34.5 ci (565 cc).
9.7:1 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 14 engines in the MZR family, sitting between the 122 ci and 152 ci members. 6 factory variants share these dimensions, rated at 160 hp across 2004–2009.
| Displacement | 138 ci / 2.261 L |
|---|---|
| Bore | 3.4449" |
| Stroke | 3.7008" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 9.7:1 |
| Bore/stroke ratio | 0.931 |
| Block material | aluminum |
|---|---|
| Head material | aluminum |
| Valvetrain | DOHC |
| Fuel type | gas |
| Redline | 6,500 rpm (factory limit) |
| Advertised HP | 160 hp |
| Years | 2004–2009 |
| Year | Version | HP @ rpm | Torque @ rpm | Comp. |
|---|---|---|---|---|
| 2004 | MZR 2.3 net | 160 @ 6500 | 150 lb-ft @ 4500 | 9.7:1 |
| 2005 | MZR 2.3 net | 160 @ 6500 | 150 lb-ft @ 4500 | 9.7:1 |
| 2006 | MZR 2.3 net | 160 @ 6500 | 150 lb-ft @ 4500 | 9.7:1 |
Factory specification sheet.
| Bore/stroke character | 0.931 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,701 ft/min — in the range typical of performance street engines |
| Displacement per cylinder | 34.5 ci |
| Static compression | 9.7:1 — 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 |
|---|---|---|
| 2004 | 160 hp | MZR 2.3 |
| 2005 | 160 hp | MZR 2.3 |
| 2006 | 160 hp | MZR 2.3 |
| 2007 | — | MZR 2.3 |
| 2008 | — | MZR 2.3 |
| 2009 | — | MZR 2.3 |
1 factory vehicle, 2004–2009. Each year opens that model's engine table.