Many consider the 5.7L LS1 as "the new 350 Chevy," but that title more accurately goes to the 5.3L Vortec truck motor. As the bread-and-butter small-block from '99 onwards, GM installs the 5.3L in the vast majority of its fullsize trucks and SUVs. Considering that GM has built way more trucks than cars in the last 10 years, the 5.3L is far more plentiful and cheaper than its 5.7-, 6.0-, 6.2-, and 7.0L big brothers. For roughly $500 at your local boneyard, complete 5.3L motors can be had for a fraction of the price of an LS1 or an LS6. Price alone, however, isn't what makes the 5.3L the biggest sleeper in the Gen III/IV camp. Its cylinder heads flow just as well in ported trim as 5.7L LS1 castings. In fact, in the early days of Gen III tweaking, before aftermarket heads became widely available, many enthusiasts preferred 5.3L heads to 5.7L LS1 heads due to the slight bump in compression that their smaller combustion chambers afforded. For those that see the 5.3L's smaller displacement as a drawback, it has sufficient cylinder wall thickness to easily accommodate the same 3.900-inch bore diameter as the 5.7L. The added durability of an iron block is tough to beat as well. From '99-07, GM built several versions of the Gen III Vortec 5300, of which the LM7 is the most common. The LM4 and L33 are aluminum-block variants of the LM7, while the L59 is a flex-fuel spinoff. GM began phasing in Gen IV 5.3Ls in '05 with the launch of the all-aluminum LH6, which replaced the LM4 in midsize SUVs. Then in '07, the iron-block, 320hp LY5 was introduced as an update to the stalwart LM7 for use in fullsize trucks and SUVs. Also that year, the LMG and LC9 were unveiled as flex-fuel versions of the LY5 and LH6, respectively. Finally, the LH8 is a slightly detuned 300hp 5.3L that powers the '09-and-up Chevy Colorado pickup.
||Cast iron or aluminum
||Iron or aluminum 15-degree cathedral port
||3.780 x 3.622
||285-320 hp and 325-340 lb-ft
|WHAT IT’S IN:
||'99+ mid/fullsize trucks and SUVs