The current LS-series small-block certainly had big shoes to fill, after all, the small-block Chevy had been around for some time and garnered more than its fair share of awards and racing success. Compared to the General's original small-block, the modern LS engine offers the veritable trifecta of performance. The LS motors are simultaneously lighter, more powerful, and more fuel efficient than their predecessors (all very important for truck owners). Offered in a variety of different displacement and power outputs, ranging from as low as 270 hp for the 4.8L up to 638 hp for the supercharged LS9 ZRI motor, performance enthusiasts have plenty to choose from. Like the previous generation of small-blocks, the LS family has its bread-and-butter motor in the form of the 5.3L (LM7). Rated at a low of 285 hp and 325 lb-ft of torque, the 5.3L combined an iron block with efficient aluminum heads and a static compression ratio of 9.5:1. The 5.3L powers literally millions of Chevy and GMC trucks, and it is this abundance that makes them so popular as a swap candidate. Luckily for 5.3L truck owners, the LS responds every bit as well as the original small-block to performance modifications. This means a more powerful truck engine is just a few simple bolt-ons away.
If there is a better way to illustrate just how responsive the LS enigne's are to performance upgrades than to stick one on the engine dyno and start tossing parts at it, we can't think of it. Given the sheer numbers and availability, the natural choice for our test motor was the LM7 5.3L, though the mods can be applied to nearly any of the LS combinations from the 4.8L up to the new 6.2L LS3/L92 variants. Rather than repeat project Novakane's bolt-on story with the engine in the truck and the heads still bolted in place, we decided to dig a tad deeper. How deep you ask? Well, we teamed up with Summit Racing for a full complement of go-fast parts that should send our 5.3L into the 450+ horsepower range. Part 1 will cover upgrading the stock 5.3L with a set of performance heads, new cam, and high-flow intake manifold, while part 2 follows up with a stroker short-block and a supercharger. More than just upgrades, we went looking for the very thing truck owners need most-namely torque. Sure, high-rpm horsepower looks good and has won more than its fair share of bench races, but torque is what actually makes the truck world go round. There is obviously a limit to absolute torque production, but our modifications were designed to simultaneously enhance torque and horsepower, while maintaining drivability. Obviously your mileage will suffer if you are "Leadfoot Larry", but the changes should have minimal effect under steady-state cruise conditions.
The first order of business was to secure a dyno-ready 5.3L test engine. This was accomplished by making a few calls to local wrecking yards. We secured a complete 5.3L pullout engine minus harness and transmission for the paltry sum of $450. Imagine, a complete engine ready to produce nearly 300 hp for just $450! These are good times to be an LS owner. Though guaranteed by the wrecking yard to run, we took the liberty of treating our 5.3L test mule to a quickie rebuild. No performance pieces were used, the engine was simply taken to L&R Automotive and freshened up by honing the cylinders and replacing the stock rings and bearings. Truth be told, the motor could have run as is, but we decided the rebuild was justified since it would be seeing more than its fair share of dyno time. The bores were lightly honed, but care was taken to allow use of the standard bore size pistons (we reused the originals). The 5.3L was run with a FAST XFI management system, set of long-tube headers and Meziere electric water pump (with no other accessories). The stock oil pan was filed with Lucas 5W-30 synthetic oil after running the motor through a proper break-in period. Run on the dyno in this configuration, the injected 5.3L truck engine produced 348 hp and 376 ft-lb of torque. Torque production exceeded 350 lb-ft from 3,200 rpm to 5,300 rpm, with the little 5.3L thumping out more than 340 lb-ft way down at 2,500 rpm.
Prior to running the LM7, we filled the stock pan with Lucas 5W-30 oil. Conventional oil w
The FAST XFI management system allowed us to dial in the timing and fuel curves to safely
All testing was run with a set of 1 3/4-inch QTP headers feeding 18-inch collector extensi