Just as Harry Hogge (Robert Duvall) said in Days of Thunder, "There's nothing stock about stock cars," there is also very little that is stock in the LS2s that Katech Performance builds for the GM Racing CTS-V race team that competes in the SCCA SPEED World Challenge [SPEED GT class]. Though the bore, stroke, and block are exactly as you would find in a production CTS-V, Katech goes to great lengths to ensure optimum performance and longevity throughout the grueling races the motor must endure. We were interested in getting an in-depth look at these "stock" motors to find out how they manage to be so powerful, yet reliable despite hours of sustained high rpm-and with permission from GM, Katech granted our wish.
Katech's Caleb Newman informed me that first each factory LS2 block undergoes thorough machining and inspection. One of the tricks of the trade, as they say, is the use of "hot honing" on the cylinders. Through heating the honing oil up to 212 degrees F while machining with a deck plate, the most realistic simulation of cylinder wall distortion is achieved. With the aluminum-block Gen III/IVs this has proven especially crucial given how "out-of-round" the cylinders become in race conditions with hot oil and coolant coursing through them. With the cylinders at their 4.005-inch max, the cam journals are CNC-bored, then honed to within spec for a set of low-friction needle bearings. Main clearance is checked (using the factory caps) and line-honed if necessary-though Katech usually finds the new blocks to be within spec. The lifter-guide orientation bosses, as well as any other unneeded bosses, are machined from the block, and provisions are made for custom oil squirters that Katech says are essential for piston life with the LS2. Rounding out the block prep work, the oil gallery is ball-honed, the dowels and the chain guide are installed, and the lifter bores are machined and new bushings are installed with a liquid-nitrogen process that, of course, must be honed prior to assembly.
Despite originally starting the CTS-V program with a completely different motor combination, Katech has perfected the rock-solid bottom end that can go up to 10 races before needing a refresher. Meticulous assembly has quite a bit to do with it. However, quality components are also accountable-such as top-dollar, Carrillo forged connecting rods; a Callies forged crankshaft; JE DLC-coated wristpins; Total Seal file fit rings; and custom Katech forged, hard anodized and Teflon-coated pistons. Given the SCCA limitations for bore, stroke, compression, camshaft, heads, intake, and throttle body diameter, Katech makes the most of the LS2 through pushing the tolerances, reducing friction, maximizing and minimizing weight, valvetrain dynamics, and reducing parasitic loss. For example, the crank spins more freely to the 7,400-rpm max with a custom dry-sump oiling system. The spec GM CNC-ported LS2 heads utilize PSI beehive springs, copper beryllium valve seats, and titanium valves and retainers. Special heavy-duty GM lifters (developed for this program and available through GMPP) are commanded by the spec cam, adding the durability required to last up to five races.
During each build Katech elects to have the SCCA inspect the motor at various stages and place its electronic seal (to prevent tampering), which avoids suspicion or having to tear apart the motor at the track after a race. Since every block lasts only 2,500 race miles, this process is repeated quite often at its facilities. And each build is completed with final assembly, including topping off the motor with stock rocker arms, intake manifold, and a custom front cover with an integrated aluminum motor plate. Then, with the stock water pump, ATI balancer, and oil scavenge pump all integrated into the serpentine belt system, the motor is run on Katech's dyno for break-in and power validation to ensure the health of the motor. Katech was tight-lipped about the LS2's power numbers, except to say that even with the 40 percent restrictor it makes over 500 hp. There is no telling how conservative this estimate is, but one thing is for sure: the CTS-Vs are certainly down on power since switching from the original destroked LS7-based motors used in years past that required even heavier restrictions. However, the use of the 40 percent restrictor still speaks volumes on the LS2's potential and how it stacks up to the V-10 Vipers and Porsche 911 GT3s. Team Remington CTS-V driver Andy Pilgrim certainly isn't complaining-at the time of publication he'd managed a podium spot at every race in the 2008 season, to say nothing of his previous success since the CTS-V's inception.
When we arrived at Katech the block had already been machined and washed. Next the rotating assembly is washed with soap and water to remove the mineral spirits, oil, dust, debris, or packing material... | 
...This makes the parts "assembly clean." Once dry, they are carried into the clean room where all of the engines are assembled. | 
The Total Seal rings have already been gapped, but before they are inserted into the ring grooves on the custom Katech pistons the clearance must be checked. If during operation the ring sticks to the back of the groove, it could prove disastrous. The rings need to move back and forth, but not butt against the groove. To verify sufficient clearance, the ring groove, land, and ring width are measured and compared. |