SCORE Journal - The Official Publication of SCORE Off-Road Racing
Issue link: http://read.uberflip.com/i/693984
ENGINE DYNO-STOCK POWER CURVES (4.8L, 5.3L, 6.0L, 6.2L ENGINES) Since all of our testing was run on the engine dyno (not the chassis dyno that delivers rear-wheel power), we though it would be a good idea to provide power numbers on popular stock LS applications for comparison. These power curves were generated by running the motors with no accessories (only an electric water pump), headers (not stock exhaust manifolds) feeding dyno mufflers and tuned to optimize power production using a stand- alone management system. The power curves offered by the four test motors (4.8L LR4, 5.3L LM7, 6.0L LQ4, 6.2L LS3) demonstrate the difference in displacement, cam timing and head flow of the various applications. Not surprisingly, the power curves increased with each hike in displacement, but note that the more aggressive cam timing (LQ4 vs LS3), improved head flow and increased compression ratio combined to greatly improve the power production of the 6.2L LS3 over the similar-sized 6.0L truck motor. worth. They dyno results show that once you have the right cam installed, the next step is improving the breathing and combustion with ported heads and the right intake manifold. UPGRADE CYLINDER HEADS AND INTAKE FOR MORE POWER GAINS While cam swaps are far and away the most popular upgrade on an LS V8 for good reason, the early cathedral-port motors will also respond well to cylinder-head upgrades. Power gains are harder to come by on the later rectangular-port motors (L92, LS3 and LS7) because the stock heads already flow enough to support over 650 hp. The dyno tests and the results in the graphs show the power gains offered by cathedral-port heads on the 6.0L stroker motor, and rectangular- port heads on the LS3. Testing on the LS3 clearly demonstrated that the combination must be plenty powerful before it can take full advantage of the extra airflow offered by ported LS3 heads. Once you have ported heads and the right cam, the final step is to install the proper intake manifold. Much like the cylinder heads, the cathedral-port combinations will respond much better to something like the Fast LSXR intake (see dyno graph) than the rectangular- port combinations (the stock LS3 intake is already very good). We have also supplied test data on single and dual- plane, carbureted intakes, and, like the previous generation small block, these intakes are basically rpm specific. Other things like displacement, forced induction and even the exhaust system all play a part in power production, but these basics should get you started on your way to understanding LS power production. 083 SCORE JOURNAL