The 8.1-liter Vortec V8 from General Motors, also known as the 8100 Vortec, is presumably the last big block V8 engine from the automaker. With 8100 Vortec production ranging from its introduction for the 2001 model year until its departure after 2007, you may wonder what the difference is between a Vortec and the popular LS engine design from the same period. GM's LS engines were designed for high-end Chevrolet Corvettes. Vortec engines, used primarily in GM pickups and SUVs, share enough LS design features that some experts use the LS moniker to cover Vortec engines as well.

The 8.1-liter Vortec shares the same 4.25-inch diameter cylinder bore as the venerable 454 cubic-inch big block. However, its longer crankshaft stroke, 4.37 inches compared to the 454's 4.00-inch value, increased the 8100's displacement to 496 cubic-inches. The longer crankshaft stroke required modifications to the Gen-VI big block, including increasing the deck height, using longer connecting rods, and extending the four-bolt main treatment to all five main bearing caps.

GM engineers used lessons taken from LS intake and exhaust manifold designs and applied them to the 8100 Vortec. Gone are the old 7.4-liter engine's mix of short and long intake ports and Siamese exhaust ports, replaced instead with nearly symmetrical, equal length intake runners and evenly spaced exhaust ports. The result is up to 340 horsepower and 455 lb-ft of torque, depending on the vehicle and trim it's found in.