The LS1 and LS6 are both 5.7-liter Gen III small-block V8s from GM. The LS1 powered the 1997-2004 C5 Corvette, rated at 345 hp and later 350 hp, as well as other GM performance cars. The LS6 was the high-output version built for the 2001-2004 Corvette Z06, rated at 385 hp in 2001 and 405 hp from 2002, thanks to higher-flowing cylinder heads, a more aggressive camshaft, higher compression and a block revised for better breathing.
LS1 vs LS6 at a glance
| LS1 | LS6 | |
|---|---|---|
| Displacement | 5.7 L (346 cu in) | 5.7 L (346 cu in) |
| Bore x stroke | 3.898 x 3.622 in | 3.898 x 3.622 in |
| Compression | About 10.1:1 | About 10.5:1 |
| C5 Corvette rating | 345 hp (1997-2000), 350 hp (2001-2004) | 385 hp (2001 Z06), 405 hp (2002-2004 Z06) |
| Used in | C5 Corvette, Camaro and Firebird, Pontiac GTO (2004) | C5 Corvette Z06, Cadillac CTS-V (2004-2005) |
What makes the LS6 different?
- Cylinder heads: higher-flowing heads with smaller combustion chambers, which also raise compression.
- Camshaft: more lift and duration for more power at high RPM, with stiffer valve springs to control it.
- Block: revised castings that let air move more freely between the cylinder bays, reducing pumping losses at high RPM.
- Intake: a higher-flowing intake manifold, which also became a popular upgrade for LS1 engines.
Because they share the same displacement, bore and stroke, many LS6 parts, especially the heads, cam and intake, were popular upgrades for LS1 owners.
Supercharging an LS1 or LS6
The C5 Corvette kits we carry are built for both engines and listed as LS1/LS6 kits, so the same kit family covers the base C5 and the Z06. Each listing states its head unit and ECS’s quoted gains. See LS1 supercharger kits and C5 Corvette supercharger kits, and read how much horsepower does a supercharger add? for what to expect. Every kit needs engine calibration and the fuel system to match.
How to tell an LS1 from an LS6
On a C5 Corvette the Z06 badge is the simplest clue, but engines get swapped, so check the RPO codes on the service parts label or the engine code in the VIN. Engine casting numbers on the heads and block confirm it. Both share the LS family’s 1-8-7-2-6-5-4-3 firing order.
LS1 and LS6 compared with later LS engines
Later Gen IV engines grew in displacement: the LS2 to 6.0 liters and the LS3 to 6.2 liters; see LS2 vs LS3. For truck LS engines and swaps, see LS vs Vortec, our LS swap guide and LS engines.
More guides: LS7 problems · LS3 vs LT1 · LS1 problems.
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