Chevrolet 350ci 12.26:1 Specs: 4.001 x 3.484 in, 247-250 hp

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Chevrolet 350ci specs: 350 ci (5.7L) 8-cylinder, 4.001 x 3.484 in (101.6 x 88.5 mm) bore and stroke, 12.26:1 compression. Rated 247-250 hp, 1990–1992. OHV.

The Chevrolet 350ci is oversquare — the 4.001" bore exceeds the 3.484" stroke by 14.8% — a layout that favors airflow and RPM over leverage at the crank. The 3.484" stroke puts mean piston speed at 4,000 ft/min around 6,900 RPM, which is where a production bottom end is generally considered at its limit. A rod ratio of 1.636 is in the range most production engines fall in. Each of the 8 cylinders displaces 43.8 ci (717 cc).

12.26:1 on iron heads is high for a production gasoline engine; running a ratio like that on pump fuel depends on chamber design and fuel delivery rather than the number alone.

It is one of 34 engines in the Chevrolet 350ci family, all of them 350 ci — the differences between them are in compression, heads and rating, not displacement. 4 factory variants share these dimensions, rated from 247 to 250 hp across 1990–1992.

Dimensions

Displacement350 ci / 5.7 L
Bore4.001"
Stroke3.484"
Cylinders8
ConfigurationV8
Compression ratio12.26:1
Rod length5.7"
Rod ratio1.636
Bore/stroke ratio1.148

Construction

Block materialcast iron
Head materialcast iron
ValvetrainOHV
Fuel typegas
Advertised HP247–250 hp
Years1990–1992

What these numbers mean

Bore/stroke character1.148 — oversquare — bore exceeds stroke, which favours higher RPM and larger valves
Mean piston speed at 6,000 RPM3,484 ft/min — conservative for a street engine
Rod ratio1.636 — moderate — the range most production V8s fall in
Displacement per cylinder43.8 ci
Static compression12.26:1 — high enough that pump premium or better is normally required

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Variants sharing these dimensions (4)

These records share identical bore, stroke, displacement and compression. They differ by model year and factory power rating.

YearAdvertised HPCode
1990247 hp—
1991247 hp—
1991250 hp—
1992250 hp—

Similar engines

← All Chevrolet 350ci engines