As previously mentioned, the industry has tended to use the designation “LS” to refer to any Gen III or Gen IV motor. From this grew the tendency to use the term LSX where X was intended to be a “variable” (like in algebra) to mean any number. Thus, the term LSX could refer to any motor who’s RPO started with the letters LS. In other words: LS1, LS2, LS3, LS4, LS6, LS7, or LS9 could all be referred to as being an “LSX”. Alternatively, the whole group could be collectively referred to as the “LSX motors”.
The only problem with this method is that there is an actual engine, or more accurately an engine block, whose actual real name is “LSX”.
Introduced in 2006, the LSX is a special cast-iron racing block based on the aluminum Gen IV LS7 engine block. Designed in conjunction with NHRA legend Warren “The Professor” Johnson, it offers displacements ranging from 364 cubic inches to 511 cubic inches. Capable of withstanding up to 2500 bhp, it is available from GM Performance Parts and has the following specs:
http://www.pirate4x4.com/tech/billavista/LSPrimer/images/Parts/LSX%20Tall%20Deck%20Block%20X09SP_PA034_resize.jpg
Photo © GM Corp. LSX Tall Deck Block
3.990' finished siamese cylinder bores (ready to be honed to your specifications) 9.70 semi-finished standard deck height (ready to be decked to your specifications) Max 4.50 recommended stroke (some additional machining required) Capable of 364 to 500+ cid (some machining may be required) Orange powder coat finish Accepts all Gen III & IV LS heads, cranks, cams, etc. Approximate finished weight : 250 lbs.