It's no secret that the new Gen III small-block is the hot engine in the performance aftermarket. Everyone has been stuffing cams and manifolds into 5.7Ls and some have even experimented with those expensive Gen III-based 427ci engines. We're planning to do our own 5.7L LS1 dyno engine buildup, but because this is Car Craft, we thought we'd start off a little differently.
Last month, we ran a story on how all the 4.8, 5.3, 5.7, and 6.0L engines offer tremendous interchangeability ("The New Generation," pg. 72, Sept. '04). Of these four, the 5.3L (325ci) truck powerplant is by far the most prolific, used predominantly in midsized pickups since 1999. That means it won't be long before this iron block, aluminum-headed small-block is filling the wrecking yards. We decided that this little engine deserved a little attention-along with a couple of camshafts, some ported cylinder heads, and an intake or two all under the careful attention of the guys at Lingenfelter Performance Engineering (LPE).
After Rob "Dyno Bob" Vanderhart bolted the stock SSR 5.3L engine on the dyno at Lingenfelter's, we began by baselining the engine completely stock including iron exhaust manifolds and the equivalent of a full exhaust system.
It should be common knowledge that our friend John Lingenfelter passed away in December of 2003. But his performance legacy continues to thrive in the Decatur, Indiana, business that he began over 30 years ago. General Manager Tom Cress and Project Director Jason Haines are just two of the many people still very much involved in cranking out powerful LPE street and race engines. Since LPE has such a distinguished performance record with these Gen III engines, we asked them if they'd be interested in aerobicizing a 5.3L. Cress immediately suggested that we step it up and do the all-aluminum 5.3L that's in the current Chevy SSR truck. LPE offers these brand-new engines for a decent price and it sounded like an outstanding idea. The plan for this month would be to test headers and a couple of camshafts to see how much power we could make. Next month, we'll add a set of LPE CNC-ported heads, and one of Comp Cams' LSXtreme intakes to see where those mods take this little 5.3. But that will have to wait until next issue.
Power Add-Ons
The production 5.3L SSR engine is a virtual clone of the iron block version except for its aluminum block, yet GM rates the SSR 5.3 at a healthier 300 hp and 330 lb-ft of torque using the SAE production car correction factor that employs a higher inlet air temperature (and other changes) that explains why the SAE corrected numbers are always lower. LPE's Rob "Dyno Bob" Vanderhart bolted the bone-stock 5.3L SSR engine to the dyno along with a complete accessory drive on the front of the engine as well as the equivalent of a muffled exhaust system connected to the stock iron exhaust manifolds. The LPE baseline in this configuration used the traditional and more lenient aftermarket correction factor and generated 313 hp and 345 lb-ft of torque, which is right in line with the factory specs assuming a 5 percent differential between the two correction factors. There may even be the advantage of a few extra ponies with an iron block compared to the aluminum version.
Exhaust work and headers are always a good place to start, so Dyno Bob bolted on a set of Hooker 131/44-inch dyno headers. Since the motor is only 325 ci, these are a little bigger than would probably be best on the street, but they were the best headers available at the time of the test because most of LPE's work is with larger and more muscular LS1s. Even with the slightly larger headers and street exhaust, the header swap was worth reasonable power throughout the entire curve.