We all know that LS engines respond well to modifications, the very best being a cam swap. So why does the cam offer so much power in an LS application? The reason is that the LS engine family is already sporting all of the other variables required to make decent power. Even a lowly truck engine has sufficient displacement, compression, and flow from the induction system (heads and intake) to produce considerably more power. All that is missing is the right cam profile, which the factory did not supply for a number of reasons. Much to our dismay, the factory was not looking to maximize power production, but was instead interested in things like emissions, fuel mileage, and even longevity (to minimize warranty claims). The uncanny ability to make power is even more pronounced on the high-performance factory versions like the LS2, LS3 and LS7. These combinations offer the most potential since they offer the very best head flow of their respective port designs.
As effective as a cam swap is on your typical LS2 (for instance), that doesn’t mean the power stops there. Unlike the LS3 and LS7, the LS2 will respond very well (after the cam swap) to additional modifications like cylinder head porting and a revised intake design. Relative to other cathedral port heads, the 243 (LS2) heads flow very well, but not compared to the factory LS3 or LS7 heads. That these rectangle port heads flow so well means power gains are harder to come by with ported or aftermarket heads. The LS2 intake is no powerhouse, bettering only the factory (original) LS1 intake for power production. In the case of the LS3, the factory intake is tough to beat, but the LS7 will respond favorably to intake manifold mods. What all this means is that a cammed LS2 is just begging for additional head flow and an intake manifold upgrade, and those are two of the mods we performed on our aluminum 6.0L test engine.
Before getting to the mods, we ran the high-mileage, cammed-up LS2 on the dyno. The aluminum 6.0L was equipped for dyno use with 1 3/4-inch long-tube headers with 3-inch-diameter collector extensions and mufflers, a Meziere electric water pump, and a FAST manual throttle body. The LS2 featured the stock intake, heads, and long-block, but had been previously upgraded with a Comp 54-459-11 (0.617/0.624-inch lift split, 231/239-degree duration split, and 113-degree LSA) cam. The cam upgrade was teamed with a set of dual valvesprings from Brian Tooley Racing. Run on the dyno, the 6.0L was sporting factory injectors controlled by a Holley Dominator EFI system. Equipped as described, the cam-only LS2 produced 492 hp at 6,300 rpm and 459 lb-ft at 5,000. The mild LS offered a reasonably broad torque curve, but the power output was nothing to write home about. What this thing needed was the right set of mods!
Rather than just install new heads and an intake, we decided the tired short-block required some attention before we could lean on it with more power. After machining the block (bored 0.005 and minimal surface), the stock pistons and rods were ditched in favor of Bullet-series components from CP/Carrillo. Known for serious internal hardware, Carrillo supplied a set of 6.125-inch rods to work with the forged, flat-top CP pistons. The rods and pistons were slung on the factory crank after minor polishing and new Sealed Power race bearings. The short-block was finished up with the installation of the already powerful 459 Comp cam, standard-travel lifters, and a Schumann’s Pro Max oil pump. To enhance airflow, we shipped the factory LS2 (243) heads off to Total Engine Airflow for some Stage 2 porting. The porting increased the airflow numbers to 320 cfm (intake) and 260 cfm (exhaust), enough to easily support in excess of 600 hp. The porting also increased the chamber volume to 67 cc, when combined with a drop in the piston position (0.004 down compared to 0.008 up on the factory piston) and the valve reliefs, the new combo was sporting a significant drop in compression (nearly 1 full point). The additional head flow had some serious ground to make up for with the drop in compression (actually our fault for not calculating beforehand).
As effective as they were, the TEA heads were not going to get the job done alone, so we topped them with a new intake manifold. The last thing we wanted to do was strangle the ported heads with the stock LS2 intake manifold. Off came the stocker and on went a new Atomic AirForce intake from MSD along with a matching 105mm Holley throttle body. Completing the intake were Holley billet fuel rails and 47-pound injectors from Accel. Once again we relied on the Holley Dominator ECU for tuning, but included a set of 1 7/8-inch Hooker headers in our list of Mighty Mods. After multiple break-in cycles, the LS2 was once again run in anger. After tuning and a switch to Lucas synthetic oil, the Mighty Mod LS2 pumped out 560 hp at 6,700 rpm and 481 lb-ft of torque at 5,400 rpm. Power increased from 4,200 rpm up to 7,000 rpm, but we can’t help but wonder what this combination would be like with the missing compression. If every point is worth 3-4 percent, we might be looking at another 15-20 hp. For now, we will revel in the glory of nearly 70 extra hp!
01. Prior to making the modifications, we ran the LS2 equipped with a Comp 459 cam, manual throttle body, and long-tube headers. So equipped, the LS2 produced 492 hp and 459 lb-ft of torque. Pay no attention to the NOS plate nitrous kit, that was run for another test.
02. After initial testing, the LS2 aluminum block was treated to a slight overbore (0.005-inch) to make room for some new rotating components. CP/Carrillo supplied a set of Bullet-series forged rods for our build up. The 6.125-inch Carrillo rods were combined with a polished factory crankshaft.
03. For our testing, we retained the original Comp cam (PN 54-459-11) that offered a 0.617/0.624-inch lift split, a 231/239-degree duration split, and 113-degree LSA. The Comp cam was teamed with a new set of matching standard travel, hydraulic roller lifters.
04. A 40-percent increase in volume was supplied by this LSX Pro Max oil pump from Schumann’s Dynamic Performance.
05. The pump included a dedicated (high-flow) pump pickup that we installed with the factory windage tray.
06. The cylinder heads were secured using Fel-Pro MLS head gaskets (PN 1061) and ARP hardware (not shown).
07. The 243 heads were shipped off to Total Engine Airflow for CNC porting. The Stage 2 porting produced peak flow numbers of 320 cfm on the intake and 260 cfm on the exhaust. The CNC work also increased the chamber volume to 67 cc.
08. The heads also received a dual valvespring package that provide both pressure and coil bind clearance for wilder cam profiles.
09. Feeding the ported TEA heads was this MSD Atomic AirForce intake manifold. The Holley aluminum fuel rails were installed using short spacers to adjust for the injector height. To feed more fuel we also dropped in a set of Accel 47-pound injectors.
10. Obviously, the free-flowing heads and intake required a suitable throttle body. This 105mm Holley unit was the perfect match for the opening in the MSD intake.
11. Naturally, the new combination required optimized air/fuel and timing values, so we enlisted the aid of this Holley Dominator EFI system.
12. The Mighty Mod LS2 was equipped with a set of 1 7/8-inch long-tube Hooker headers with collector extensions. Note the Holley oxygen sensor used in the header to monitor the air/fuel ratio for the Dominator system.
13. After the break-in procedure, the modded LS2 produced 560 hp at 6,700 rpm and 481 lb-ft of torque at 5,400 rpm. Plans now are to restore the lost compression and port match the heads and Atomic intake to see how much more power we can coax out of it.
14. The LS2 was already sporting a healthy Comp cam when we first installed it on the dyno. When combined with the already impressive 243 LS3 heads, even the otherwise stock LS2 was sporting some impressive power. This mildly modified LS2 produced 492 hp at 6,300 rpm and 459 lb-ft of torque at 5,000 rpm. After performing the mods (forged short-block, TEA heads, and Atomic intake), the peak numbers jumped to 560 hp at 6,700 rpm and 481 lb-ft of torque at 5,400 rpm. The new combo was sporting reduced compression (nearly a full point) compared to the stock short-block (piston down 0.004, valve reliefs, and larger chambers on the TEA heads), but we plan to remedy that by having Brian Tooley Racing mill (and fine tune) the 243 heads, port match the intake, and then install a revised cam profile. We loved these mods, but can’t wait to see how much the next round of changes will offer.