Third Generation GM small block V8

The LS1 engine is the latest evolution of the small-block V-8 engine Chevrolet introduced in 1955. Although touted by GM as an evolutionary development, it is more realistic to call the LS series engine a clean sheet design, sharing only bore spacing dimensions with the original small block.

  Although called a 350 by GM, actual displacement is 346 cubic inches.  In the Corvette, in stock configuration, this engine produced a factory-rated 345 HP, virtually 1 HP per cubic inch.  With emphasis on servicibility, most of the gastkets used are re-usable, and an engine can be completely disassembled in just a few minutes.  The fireing order of the cylinders is different from the traditional small blocks, with some enthusiasts complaining, and others saying that it provides a more exotic, European sound.
  Already several variants have been produced, the initial LS1, the LS6 with a different cam and intake manifold and changes within the aluminum block to minimize pumping losses, and a larger LS7.  This engine appears to be poised to be the bread and butter engine for GM performance for the foreseeable future.