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Pontiac 207ci specs: 207 ci (3.4L) 6-cylinder, 3.62 x 3.31 in (91.9 x 84.1 mm) bore and stroke, 10:1 compression. Rated 170-210 hp, 1995–1999.
The Pontiac 207ci is oversquare — the 3.62" bore exceeds the 3.31" stroke by 9.4% — a layout that favors airflow and RPM over leverage at the crank. The 3.31" stroke does not reach 4,000 ft/min of mean piston speed until about 7,250 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. A rod ratio of 1.722 is in the range most production engines fall in. Each of the 6 cylinders displaces 34.5 ci (565 cc).
10:1 on iron heads is in the range that usually runs on pump premium; iron holds heat, so treat it as the less forgiving side of that range.
It is one of 4 engines in the Pontiac 207ci family, the largest at 207 ci. 2 factory variants share these dimensions, rated from 170 to 210 hp across 1995–1999.
| Displacement | 207 ci / 3.4 L |
|---|---|
| Bore | 3.62" |
| Stroke | 3.31" |
| Cylinders | 6 |
| Configuration | I6 |
| Compression ratio | 10:1 |
| Rod length | 5.7" |
| Rod ratio | 1.722 |
| Bore/stroke ratio | 1.094 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 170–210 hp |
| Years | 1995–1999 |
| Bore/stroke character | 1.094 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,310 ft/min — conservative for a street engine |
| Rod ratio | 1.722 — moderate — the range most production V8s fall in |
| Displacement per cylinder | 34.5 ci |
| Static compression | 10:1 — 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 |
|---|---|---|
| 1995 | 210 hp | — |
| 1999 | 170 hp | — |