5.3 vs 5.7 LS: what's the difference?

The 5.7 (LS1/LS6) was the Gen III car engine; the 5.3 (LM7 and relatives) was the truck engine. Both use the same 3.622 in stroke — the extra displacement comes from the bigger bore (3.898 in vs 3.78 in). Here's the most common of each:

	LM7	LS1
Family	Generation III	Generation III
Years	1999–2007	1997–2005
Displacement	5.3 L (325 ci)	5.7 L (346 ci)
Power	270–295 hp	295–382 hp
Torque	315–335 lb-ft	323–376 lb-ft
Bore × stroke	3.78 × 3.622 in	3.898 × 3.622 in
Compression	9.49:1	10.25:1
Block	iron	aluminum
AFM/DOD	no	no
VVT	no	no
Direct injection	no	no
VIN 8th digit	T	—

Key differences:

• Bore: LM7 3.78 in, LS1 3.898 in
• Block: LM7 iron, LS1 aluminum
• Compression: LM7 9.49:1, LS1 10.25:1

For a swap: our donor table lists 55 vehicle applications for Gen III/IV 5.3 engines versus 19 for the 5.7 LS1/LS6 — mostly full-size trucks and SUVs for the 5.3, cars for the 5.7. Compare every option in the donor finder.

Specs are GM ratings as published; power varied by year and vehicle. Confirm any engine by the RPO code on the glovebox/console sticker.