How much horsepower does a stock 5.3 make?
It depends on the version: GM ratings range from about 270 hp (1999 LM7) to 355+ hp (Gen V L83). Common Gen III/IV 5.3s:
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- LM7 (1999–2007, iron): 270–295 hp, 315–335 lb-ft
- L59 (flex-fuel, iron): 285–295 hp
- L33 (aluminum "HO"): 310 hp, 335 lb-ft
- LH6 (aluminum, AFM): 300–315 hp
- LY5 / LMG (iron, AFM): 315–320 hp, 335–340 lb-ft
- LC9 (aluminum, AFM): 315–320 hp
Speedway Motors summarizes a typical stock 5.3 as about 320 hp / 340 lb-ft. A cam swap alone took their junkyard LM7 to about 430 hp.