Infiniti KR specs: 84 x 90.1 mm (3.3071 x 3.5472 in) bore and stroke, shared by all 4 versions. Displacement, compression and factory ratings, plus rod ratio.
| Displacement | 91.5–122 ci |
|---|---|
| Cylinders | 3, 4 |
| Bore | 3.307" |
| Stroke | 3.547" |
| Compression | 8.0–14.0:1 |
| Advertised power | 201–268 hp |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| KR20DDET | 122 ci | 3.3071" × 3.5472" | 14:1 | 268 |
| KR20DDET | 121.9 ci | 3.3071" × 3.5472" | 8:1 | 268 |
| KR20DDET | 121 ci | 3.3071" × 3.5472" | 14:1 | 268 |
| KR15DDT | 91.5 ci | 3.3071" × 3.5472" | 8:1 | 201 |
Compression spans 8:1 to 14:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.
All 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.