lsx

"LS engine" is the colloquial name given to the 3rd and 4th generation small-block V-8 gasoline engine used in General Motors' vehicles. The name evolved from the need to differentiate the Gen 3/Gen 4 small blocks from the original Gen 1/Gen 2 small blocks released in 1954, which are commonly referred to as "Small Block Chevrolets". The "LS" name originates from the engine RPO code of the first Gen 3 small block, the LS1, introduced in the 1997 Corvette. The term "LS engine" is used to describe any Gen 3 or Gen 4 Small Block Chevrolet, including those that do not specifically include "LS" as part of their RPO code. Sometimes referred to as an "LSx", with the lower case "x" standing in for one of the many RPO code variations of the motor, the term can cause confusion since GM now sells an aftermarket LS cylinder block named "LSX" with a capital "X". The original RPO code "LS1" is still sometimes used, if not confusingly, to describe the entire Gen 3/Gen 4 engine family.
LS engines were a clean sheet modular design. Most components interchange between these Gen 3 and Gen 4 motors. LS motors share no interchangeable parts except connecting rod bearings with the Gen 1/2 Small Block Chevrolet engines. Likewise, while GM engineers clearly took design inspiration from the LS motor when creating their 5th Generation "LT" Small Block in 2014, it was predominantly a new design. There is almost no parts interchange between the LS and LT families.
All cars sold with LS motors were equipped with aluminum blocks while most trucks received cast iron blocks. LS engines enjoy several notable improvements over previous generations of small blocks. The lower section of the block incorporates deep side skirts along with 4-bolt cross-bolted main bearing caps and a structural cast aluminum oil pan. Nearly all LS motors were manufactured with high airflow aluminum cylinder heads, even in truck applications. The design uses long runner intake manifolds to enhance airflow within the engines operating range. These dry intake manifolds omit the coolant passages of earlier generations to minimize heat uptake in the air charge. They are made from a light weight yet durable nylon polymer. A large improvement was made to the ignition system by forgoing the camshaft driven distributor of the early small blocks in favor of valve cover mounted ignition coils, one for each cylinder. LS ignition timing is handled by the ECU thanks to camshaft and crankshaft position sensors.
GM engineered the LS as a pushrod motor which was a controversial choice at the time. It was seen as an old school low tech decision that could not compete with the more high tech dual over head cam strategy (DOHC) that Ford had adopted. GM had their reasons though and it turned out to be an unprecedented success. The choice kept the cost of the engines low, allowing them to be installed in a large variety of vehicles. The cam in block strategy kept the external size of the motor down relative to DOHC design, while still allowing 7.0L (427ci) displacements in stock form. Combined with the airflow potential of well engineered cylinder heads and intake manifolds, this added displacement allowed higher outputs in a smaller external package relative to a DOHC configuration. The combination of a small package size, low cost and availability has earned LS motors a cult like following among engine swap hobbyists where slogans like "LS Swap the World" are often echoed. This popularity has spurred a tremendous level of support from the automotive aftermarket industry and has been a cultural phenomenon as social media has exploded with LS content from sources like Sloppy Mechanics and Richard Holdener. Grass roots racers are now chasing stock bottom end "SBE" records pushing factory hardware to in-excess of 1500 hp and running 7 second 1/4 miles at 170+ even with 4.8L, the smallest of the factory LS displacements.
Much of the credit for this engine family must go to Ed Koerner, GM's Powertrain vice president of engineering operations at the time. He was a V-8 design veteran and former National Hot Rod Association (NHRA) record holder in drag racing. Koerner had been the Chief Engineer for all the existing GM small-block V-8 engines and was put in charge of the "all-new" Gen III LS1 V-8 development project, which would share no parts with previous engines. Design team members included Alan Hayman, Jim Mazzola, Ron Sperry, Bill Compton, Brian Kaminski, Jon Lewis, Stan Turek, Don Weiderhold, and Dave Wandel.

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