Bore, stroke, displacement and compression for all 4 Pontiac OHC-6 engines, compared side by side. Plus rod ratio and head specs where published.
| Displacement | 230–250 ci |
|---|---|
| Cylinders | 6 |
| Bore | 3.874" |
| Stroke | 3.252–3.531" |
| Compression | 9.0–10.5:1 |
| Advertised power | 160–215 hp |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Pontiac OHC-6 · 3.874" × 3.531" · 9:1 | 250 ci | 3.874" × 3.5315" | 9:1 | 165–175 |
| 250 Ohc6 Sprint | 250 ci | 3.874" × 3.5315" | 10.5:1 | 215 |
| Pontiac OHC-6 · 3.874" × 3.252" · 9:1 | 230 ci | 3.874" × 3.252" | 9:1 | 160–165 |
| OHC 6 Sprint | 230 ci | 3.874" × 3.252" | 10.5:1 | 207 |
Every engine here shares a 3.874" bore; displacement varies by stroke alone, which is the signature of a family built on one block with different cranks.
Compression spans 9:1 to 10.5:1, so fuel requirements differ meaningfully between members — worth checking before assuming parts interchange.
All are oversquare — bore larger than stroke, which favours revs over low-end torque.
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.