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Pontiac 145ci (2006) · 177 hp specs: 145 ci (2.4L) 4-cylinder, 3.465 x 3.858 in (88 x 98 mm) bore and stroke, 10.4:1 compression. Rated 177 hp, 2006. OHC.
The Pontiac 145ci (2006) · 177 hp is undersquare — the 3.858" stroke exceeds the 3.465" bore by 10.2% — a layout that trades peak RPM for leverage and torque low in the range. The 3.858" stroke puts mean piston speed at 4,000 ft/min around 6,200 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.467 is short — higher piston acceleration and more side-load, typical of stroker combinations and a reason to watch piston speed closely. Each of the 4 cylinders displaces 36.3 ci (594 cc).
10.4:1 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.
| Displacement | 145 ci / 2.4 L |
|---|---|
| Bore | 3.465" |
| Stroke | 3.858" |
| Cylinders | 4 |
| Configuration | I4 |
| Compression ratio | 10.4:1 |
| Rod length | 5.661" |
| Rod ratio | 1.467 |
| Bore/stroke ratio | 0.898 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHC |
| Fuel type | gas |
| Advertised HP | 177 hp |
| Years | 2006 |
| Bore/stroke character | 0.898 — undersquare — stroke exceeds bore, which favours low-end torque |
|---|---|
| Mean piston speed at 6,000 RPM | 3,858 ft/min — in the range typical of performance street engines |
| Rod ratio | 1.467 — short — more side loading and piston dwell at TDC, typical of stroker combinations |
| Displacement per cylinder | 36.3 ci |
| Static compression | 10.4:1 — in the range that usually runs on pump premium |
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