At the GM Performance Build Center in Wixom, Michigan, you won't find anybody piecing together hybrid engines, diesel mills, or powerplants fueled by used cooking grease. They're not tasked with making tree huggers happy, although the engines they turn out are surprisingly Mother Earth friendly. Their sole job is to produce the general's most powerful and extreme engines-mechanical works of art that are as powerful as they are reliable. in short, they're in the horsepower business.
Most GM plants are staffed by hundreds of people and dozens of robots, but the Wixom plant is different. it's an almost intimate affair. With only 38 employees-25 of them master builders-the Performance Build Center (PBC) combines the efficiency of technology with oldschool race engine building principals. The result is engines that put out big power and, at the same time, have commuter car reliability.
The Eaton Twin Vortices Series...
The Eaton Twin Vortices Series (TVS) gen Vi supercharger is all about pumping out power while staying as compact as possible. inside the supercharger is a new, four-lobe rotor arrangement that tops 15,000 rpm, helping sustain airflow at high engine rpm. also, the intermeshing design of the lobes helps quiet the supercharger, even at high rpm. in fact, the new gen Vi four-lobe blower design provides up to 10 dBa less case-radiated noise than the gen V blower.
Opened in '03, the PBCs first mission was to hand-assemble the 427ci lS7 for the new C6 ZO6. later, it was also given the task of meticu- lously assembling the blown lSa engine in the V-series Caddies. But now they have a new beast lurking under their roof-the supercharged lS9. Conceived after the introduction of the 505hp lS7, the lS9 was designed to be the pinnacle of GM pushrod technology.
Engineers were given three rules: The lS9 had to make huge power; the engine had to be as reliable as any other GM production engine; and it had to fit in a C6 Corvette. Meeting any two of these goals was pretty easy, they said, but accomplishing all three required a huge amount of engineering and innovation. The result is a mechanical masterpiece that is to V-8 engines what Jessica alba is to the female form-jaw dropping.
It's not so much that the engine churns out 638 horsepower and 604 lb-ft of torque. it's that it does it so smoothly and effortlessly. The lS9 is a supercharged engine that doesn't suffer the typical fate of heat soak because the blower isn't pushed near its capacity. it idles smoother than a less-powerful lS7, and it's nearly impossible to hear the blower spinning under the hood. Sure, you could go crazy hot rodding an lS7 and make the same power, but it would be nowhere as civilized as an lS9. Then again, the lS9 is only civilized in terms of items like idle quality. When it comes to putting down power, it's the proverbial barbarian at the gate.
GM decided from the get-go that this engine had to be hand-built like the lS7, but gM doesn't hand-build something like you and i would. With its resources, it's about as high-tech a procedure as it gets while still under human control. When we got the invite to go inside Wixom to help build one of the first-production engines, we nearly pulled a tendon in our rush to book a flight. After all, history was about to be made and we had no intention of missing out.
The new lS9 exceeds the lS7 in every area except one- displacement. The main reason for the drop in displacement was strength. GM's plan for the lS9 included a supercharger and the 427ci block wasn't strong enough to reliably hold up to the intended boost. instead, a beefed-up 6.2-liter lS3 block is used. Starting in '09, all 6.2l blocks, including truck blocks, will feature this 20 percent increase in bulkhead strength. The 319-T5 aluminum block, with forged steel bearing caps, is deck-plated bored and honed. By sharing the casting across the lS3 line, costs will be kept down. after the blocks arrive they are inspected and re-cleaned on site.