Oldsmobile L31 / W-32 Specs: 4.126 x 4.25 in, 365 hp

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Oldsmobile L31 / W-32 specs: 455 ci (7.5L) 8-cylinder, 4.126 x 4.25 in (104.8 x 108 mm) bore and stroke. Rated 365 hp, 1970. Used in the Oldsmobile Cutlass.

The Oldsmobile L31 / W-32 is close to square: 4.126" bore against 4.25" stroke, within 2.9%, which splits the difference between a high-revving layout and a torque layout. The 4.25" stroke puts mean piston speed at 4,000 ft/min around 5,650 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.585 is in the range most production engines fall in. Each of the 8 cylinders displaces 56.9 ci (932 cc).

It is one of 9 engines in the Oldsmobile 455ci family, all of them 455 ci — the differences between them are in compression, heads and rating, not displacement.

Dimensions

Displacement455 ci / 7.5 L
Bore4.126"
Stroke4.25"
Cylinders8
ConfigurationV8
Rod length6.735"
Rod ratio1.585
Bore/stroke ratio0.971

Construction

Block materialcast iron
Head materialcast iron
ValvetrainOHV
Fuel typegas
Advertised HP365 hp
Years1970

What these numbers mean

Bore/stroke character0.971 — square — bore and stroke are within 5%, a balanced compromise
Mean piston speed at 6,000 RPM4,250 ft/min — in the range typical of performance street engines
Rod ratio1.585 — moderate — the range most production V8s fall in
Displacement per cylinder56.9 ci

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