Oldsmobile 371 Specs: 4.00 x 3.70 in, 277 hp

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Oldsmobile 371 specs: 371 ci (6.1L) 8-cylinder, 4.00 x 3.70 in (101.6 x 94 mm) bore and stroke, 9.25:1 compression. Rated 277 hp. Rod ratio and piston speed.

The Oldsmobile Rocket (371) is oversquare — the 4" bore exceeds the 3.7" stroke by 8.1% — a layout that favors airflow and RPM over leverage at the crank. The 3.7" stroke puts mean piston speed at 4,000 ft/min around 6,500 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 46.4 ci (760 cc).

9.25:1 on iron heads is low by modern standards and generally happy on regular pump fuel.

It is one of 15 engines in the Rocket family, sitting between the 260 ci and 455 ci members. Factory fitments include the Oldsmobile 88, Oldsmobile 98, Oldsmobile Super 88.

Dimensions

Displacement371 ci / 6.1 L
Bore4"
Stroke3.7"
Cylinders8
Compression ratio9.25:1
Bore/stroke ratio1.081

Construction

Block materialcast iron
Head materialcast iron
ValvetrainOHV
Fuel typegas
Advertised HP277 hp

What these numbers mean

Bore/stroke character1.081 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM3,700 ft/min — in the range typical of performance street engines
Displacement per cylinder46.4 ci
Static compression9.25:1 — low by modern standards, generally happy on regular pump fuel

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