Bore, stroke, displacement and compression for all 4 Plymouth K-Engine engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 135–153 ci |
|---|---|
| Cylinders | 4 |
| Bore | 3.445" |
| Stroke | 3.622–4.095" |
| Compression | 7.8–9.0:1 |
| Advertised power | 84–150 hp |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| 25 K I4 | 153 ci | 3.4449" × 4.0945" | 9:1 | 100 |
| 25 K Turbo | 153 ci | 3.4449" × 4.0945" | 7.8:1 | 150 |
| 2.2L | 135 ci | 3.4449" × 3.622" | 8.5:1 | 84 |
| Turbo I | 135 ci | 3.4449" × 3.622" | 8.1:1 | 142–146 |
Every engine here shares a 3.4449" bore; displacement varies by stroke alone, which is the signature of a family built on one block with different cranks.
2 of 4 are undersquare — stroke larger than bore, favouring torque low in the range.
Each engine page carries rod ratio, mean piston speed, bore/stroke character and cylinder head specs where published, and links into the calculators with its dimensions already filled in.