The new heads are unique,...
The new heads are unique, the valves have been reoriented so the center exhaust ports are no longer adjacent and the new ports give the fuel injectors a direct shot at the intake valves.
Like most contemporary engines, the LS1 uses roller lifters as well as investment cast roller rockers, but one of the most unique pieces is a manifold from composite material that allows for the curved runner configuration while being light and cost effective. Another new feature found on the manifold is the fly-by-wire throttle body. The LS1 was the first GM engine in cars to use a computer-controlled throttle (light-duty diesel trucks began using them in '95).
Of all the features of the LS1 that are out of the ordinary, the most obvious are the rocker cover-mounted coil assemblies. Each cylinder has its own coil and coil driver assembly with a short secondary wire connecting to each spark plug. The reasons given for moving the coils to the covers is that the shorter plug wires lost less energy so more is delivered to the plug, as well as reduced radio frequency interference with on-board computers. A less noticeable feature of the ignition system is the change in firing order; no longer using the familiar 1-8-4-3-6-5-7-2 sequence, new engines fire 1-8-7-2-6-5-4-3.
With all that is unique on the LS1, one of the pieces that almost escapes notice is the pan-but there's more to it than meets the eye. There have been a half-dozen or more cast-aluminum pans used on these engines: the Corvette, or batwing pan, is a two-piece and has two wings to the sides, and the Camaro and Firebird pans have a shallow rear sump. But no matter what the shape is, in all cases the pan becomes a part of the engine's structure when screwed in place and contributes to the block's rigidity. An unusual feature is these pans also provide a mount for the oil filter.
Crate Motor Offerings
Currently, General Motors Performance Parts offers a variety of LS engines-they include:
GMPP describes the 5.3L as having the same 327-cubic-inch displacement of the small-blocks from the '60s but in a new LS package. It's been equipped with a hotter than stock cam and Grafal-coated high-silicon pistons.
The first and most popular version of the series-the LS1 features a deep skirt, six-bolt main block, with structural oil pan, a high-lift camshaft actuating big 2.00/1.55-inch valves in symmetrical-port cylinder heads. Rated at 350 horsepower and 365 lb-ft of torque it comes with a GTO-style oil pan, electronic drive-by-wire throttle body, intake manifold, exhaust manifolds, fuel rail with injectors, balancer, and 14-inch automatic transmission flexplate.
Producing more than 400 horsepower, the LS6 has been equipped with hollow-stem valves, a more aggressive camshaft, improved intake and higher-rate valvesprings along with higher-compression pistons to raise horsepower to 405, and torque to 400 lb-ft. It comes with a CTS-V oil pan, large-volume composite intake manifold with single-bore throttle body, and high-performance long-style exhaust manifolds.
This 6.2-liter engine produces 430 horsepower and 424 lb-ft of torque thanks to revised cylinder heads featuring rectangle ports, 63cc combustion chambers, 2.16-inch intake valves, and 1.59-inch exhaust valves. The camshaft has 0.551-inches of lift on the intake side with less overlap (than the LS2) and 1.7:1 ratio rocker arms are used. The aluminum six-bolt main block features 4.06-inch bores and 3.62-inch stroke, a nodular iron crankshaft, powdered metal rods, and aluminum pistons with a compression ratio of 10.7:1.
An LS3 with an upgraded camshaft (PN 12617570) with 0.525-inch intake and exhaust valve lift. The duration is 219 degrees intake and 228 degrees exhaust (at 0.050-inch lift). Said to idle and cruise just like an LS3, this cam is good for 50 horsepower.
An upgraded LS3 that is equipped with an aggressive camshaft and GM Performance Part's exclusive carbureted intake manifold produces 515 horsepower. The hydraulic roller camshaft has 0.525-inch intake and exhaust valve lift with duration of 226 degrees on the intake and 236 on the exhaust.