Pontiac 173ci specs: 3.50 x 3.00 in (88.9 x 76.2 mm) bore and stroke, shared by all 8 versions. Displacement, compression and factory ratings, plus rod ratio.
| Displacement | 173 ci |
|---|---|
| Cylinders | 6 |
| Bore | 3.500" |
| Stroke | 3.000" |
| Compression | 9.0–9.2:1 |
| Advertised power | 102–135 hp |
| Years | 1982–1989 |
| Cylinder head data | 3 of 8 engines |
| Engine | Displacement | Bore × Stroke | CR | HP |
|---|---|---|---|---|
| Pontiac 173ci (1986) · 135 hp | 173 ci | 3.5" × 3" | 9:1 | 135 |
| Pontiac 173ci (1988) · 135 hp | 173 ci | 3.5" × 3" | 9.2:1 | 135 |
| Pontiac 173ci (1989) · 130 hp | 173 ci | 3.5" × 3" | 9.1:1 | 130 |
| Pontiac 173ci (1989) · 135 hp | 173 ci | 3.5" × 3" | 9.14:1 | 135 |
| LC1 | 173 ci | 3.5" × 3" | — | 102–107 |
| LL1 | 173 ci | 3.5" × 3" | — | 125 |
| LB8 | 173 ci | 3.5" × 3" | — | 135 |
| LB6 | 173 ci | 3.5" × 3" | — | 130 |
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.