LS3
The LS3 replaced the LS2 in the Corvette in 2008. It added more Displacement and rectangle port heads for more Horsepower and Torque . The LS3 was available in GM performance cars until 2017.
L99
The L99 was an adapted version of the LS3. It was ONLY available in the 2010-15 Camaro SS with an automatic transmission. It used different pistons, crankshaft, camshaft, and valves. It also added Active Fuel Management (AFM) and Variable Valve Timing (VVT). This scaled back the power a little bit. But, it was more compatible with the auto trans.
For specific details about these engines, please follow the links below:
Benefits
These engines are built for performance. They have a 4.065 in. bore diameter for more displacement. They also use rectangle port heads that flow more air. With the right combination of parts, the stock heads can support over 600 hp. The block can handle up to 1,000 hp with upgraded internals.
Like all Gen. 4 blocks, they have the internal oil passages for AFM, even if it wasn't used.
What's the difference?
The easiest way to tell the difference is to check the 8th digit of the VIN code.
- Follow this link to Identify an LS Engine by VIN.
The difference between the engines is the heads and the special technology used on each one.
- Follow this link to Identify AFM.
- Follow this link to Identify VVT.
| RPO Code | AFM | VVT | Cylinder Head Casting Number |
| LS3 | No | No | 821 |
| L99 | Yes | Yes | 823 |
Special Notes
- The LS3 used lighter, hollow-stem intake valves.
- The L99 used pistons w/ valve reliefs for added clearance with the VVT system.
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- This resulted in a slightly lower compression ratio.
- A special dry sump version of the LS3 was used in the 2010-13 Corvette Grand Sport Coupe only.
- The dry sump LS3 used:
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- A longer, forged steel crankshaft to accommodate the oil pump,
- A shallow oil pan,
- A 10.5 qt, remote oil tank, and
- A 3-bolt camshaft.