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Plymouth G specs: 170 ci (2.8L) 6-cylinder, 3.402 x 3.126 in (86.4 x 79.4 mm) bore and stroke, 8.2:1 compression. Rated 101 hp. Rod ratio and piston speed.
The Plymouth Slant-6 (G) is oversquare — the 3.4016" bore exceeds the 3.126" stroke by 8.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.126" stroke does not reach 4,000 ft/min of mean piston speed until about 7,700 RPM, so piston speed is not what limits this engine's revs — valvetrain and breathing are. Each of the 6 cylinders displaces 28.3 ci (464 cc).
8.2:1 on iron heads is low by modern standards and generally happy on regular pump fuel.
It is one of 13 engines in the Slant-6 family, the smallest at 170 ci. 2 factory variants share these dimensions, rated at 101 hp. Factory fitments include the Plymouth Valiant, Plymouth Barracuda, Valiant and 1 other.
| Displacement | 170 ci / 2.8 L |
|---|---|
| Bore | 3.4016" |
| Stroke | 3.126" |
| Cylinders | 6 |
| Compression ratio | 8.2:1 |
| Bore/stroke ratio | 1.088 |
| Block material | cast iron |
|---|---|
| Head material | cast iron |
| Valvetrain | OHV |
| Fuel type | gas |
| Advertised HP | 101 hp |
| Bore/stroke character | 1.088 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves |
|---|---|
| Mean piston speed at 6,000 RPM | 3,126 ft/min — conservative for a street engine |
| Displacement per cylinder | 28.3 ci |
| Static compression | 8.2:1 — low by modern standards, generally happy on regular pump fuel |
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 |
|---|---|---|
| — | 101 hp | G |
| — | 101 hp | G-Engine, G |