GMPP LS3 vs. TSP Cam and TEA L92 Heads
As important as the huge jump in peak power (from 485 to 574 hp) is the significant improvement in torque production (from 476 to 520 lb-ft) throughout the rev range. These gains are even more impressive when you consider that the TEA heads came equipped with slightly larger combustion chambers than did the stock LS3 units (70cc vs. 68cc), dropping the static compression by nearly 0.2 points.
GMPP LS3 vs. TSP Cam and Dr. J's 81cc ProComp Heads
Despite dropping the compression ratio from 10.7:1 to 9.4:1, the ported ProComp heads and Texas Speed cam improved the output of the LS3 crate motor from 485 hp and 476 lb-ft of torque to 538 hp and 495 lb-ft. Knowing that every point of compression drops power output by 4 percent, we can calculate that with the stock chamber size, these heads would produce in the neighborhood of 565-570 hp. A full test of the standard-chamber heads will be completed soon, but for now it's clear that these large-chamber offerings combine plenty of flow with a drop in compression that makes them ideal for forced induction.
We took a set of large-chamber L92 heads from ProComp and had Dr. J's "tune them up" so we could run them on our LS3 (see graph). Thus modified, the ported ProComp heads offer impressive flow numbers, enough to support more than 700 hp in normally aspirated trim. Combine that with the drop in compression, and you have some seriously powerful blower heads. ProComp also offers LS3 heads in standard chamber sizes for the NA crowd, and Dr. J's can tune them for big-time power production.
If you're considering a supercharger or turbo for your LS3, here's an interesting option to explore: ProComp Electronics now offers dedicated LS3 head castings in as-cast and CNC-ported form. What makes them so attractive for forced-induction applications is that they're available with combustion chambers measuring 80-81 cc's, compared with just 68-70 cc's for the production LS3/L92 heads. The larger chambers drop the compression ratio by 1.3 points, bringing it down to a more boost-friendly 9.4:1.