Chevrolet LY5 / LC9 specs: 325 ci (5.3L) 8-cylinder, 3.78 x 3.622 in (96 x 92 mm) bore and stroke. Rated 320 hp, 2009. Used in the Chevrolet Avalanche. OHV.
The Chevrolet LY5 / LC9 is close to square: 3.7799" bore against 3.622" stroke, within 4.4%, which splits the difference between a high-revving layout and a torque layout. The 3.622" stroke puts mean piston speed at 4,000 ft/min around 6,650 RPM, which is where a production bottom end is generally considered at its limit. Each of the 8 cylinders displaces 40.6 ci (666 cc).
It is one of 61 engines in the LS family, sitting between the 293 ci and 454 ci members.
Dimensions
Displacement
325 ci / 5.3 L
Bore
3.7799"
Stroke
3.622"
Cylinders
8
Configuration
V8
Compression ratio
9.6–9.95:1 (published figures vary)
Bore/stroke ratio
1.044
Construction
Block material
aluminum
Head material
aluminum
Valvetrain
OHV
Fuel type
gas
Firing order
1-8-7-2-6-5-4-3
Advertised HP
320 hp
Years
2009
What these numbers mean
Bore/stroke character
1.044 — square — bore and stroke are within 5%, a balanced compromise
Mean piston speed at 6,000 RPM
3,622 ft/min — in the range typical of performance street engines
Displacement per cylinder
40.6 ci
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