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Corvette ZR1 High Tech LS9 - First Look: Building The ZR1's 638HP Engine

We Head Inside The Wixom Performance Build Center To See What's Involved In Assembling The New Supercharged Ls9.

By , Photography by Courtesy of GM,

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.

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.

Before being installed, the camshaft is given a liberal bath in Mobil 1 oil. also, notice the custom installation tools that keep the cam (211/230 @ .050 and .562/.558 lift) from nicking the cam bearings. Think they got this idea from corn on the cob?

Unlike the lS7, which has a cast crank, the lS9 wields a forged steel micro-alloy crankshaft. it's easy to identify since it has nine flywheel boltholes in the back compared to six on the lS7 crank. GM engineers believe more is better due to the increased output of the engine.

Here you can see one of the eight new oil squirters that arrive mounted in the block. These squirters keep chamber temperatures down and reduce drivetrain noise. This is the first time that General Motors has used oil squirters in a small-block application.

The build process relies heavily on computers, but the builders still use old school methods. One of these is marking all of their main caps with orange paint, even though they're stamped at the factory.

The use of exotic titanium in the engine rods will continue, but gM has moved to forged 9.1:1 compression pistons. The floating pin pistons are anodized on the top and the skirts are polymer coated. The engines are assembled by the builder at a series of 11 stations. at each station, the parts needed for that station are provided in kitting trays like this one. lS9 parts are placed in green bins and racks so they won't be confused with lS7 parts.

This tool is specific to the LS9 assembly and helps guide the rod into the engine. in addition to making sure no damage is done to the crank, its main job is to ensure the rod doesn't damage the oil squirter. Custom tools like this are located all along the line to guarantee high build quality.

Each station is laid out to accomplish a specific task. Only the tools and parts needed for that station are on hand. The task sheets are colorcoded green for lS9 and white for lS7 engines. Note the white template that shows the order in which the bolts need to be torqued. Most of the builders know the pattern by now, but they are there for reference. The white plastic tray on the left side of the workbench is where lS7 parts are "kitted."

The biggest difference between how you assemble an engine and how gM does it is in the use of specialized tools. This alignment tool makes sure the timing cover is dead center to the crank. The top plate ensures that the bottom of the cover is flush to the block. This is critical to ensure a leakfree seal to the oil pan.

Oil capacity was increased for the lS9 since the ZR1 Vette has an expanded performance envelope compared to the ZO6. The result is a 33 percent increase in oil capacity. This means you'll need 10.75 quarts of oil instead of the previous eight quarts when you do an oil change. The increased oil supply means the mill handles 30 percent more g's. The extra demands of the supercharger prompted gM to design a new LS oil filter with a thicker housing to resist bulging.

There are three of these screens throughout the build line and they are used as check stations. Skip a step, the face will be red and sad. fortunately ours was smiling, so we could move onto the next station.

Not all of the tools used are super high-tech widgets. This jig was designed by one of the builders and properly aligns all the rockers so they can be quickly installed. Neat idea.

At Station 8, the lS9 gets its water pump. for packaging reasons the blower belt also spins the water pump. To handle the extra strain, the pump's bearing was beefed up by gM's engineers.

With the Eaton gen Vi Twin Vortices Series (TVS) supercharger bolted in place, the intercooler can be installed. The new air-to-liquid tube-in-fin intercooler will help lower inlet temps by up to 140 degrees f. The larger displacement of the new gen Vi unit expands the range of the compressor's effectiveness, building power more quickly at lower rpm and sustaining it through higher rpm. The 2.3l displacement of the Eaton will provide maximum boost of 10.5 psi. according to gM, the lS9 doesn't suffer from heat soak.

Organization at Wixom extends to the parts as well as the tools. This system makes it easy for the builder to be sure he is supplied with every part needed for a station and to ensure that all of those parts end up on the engine. Note the new lS9 valve covers. They no longer have the ugly racks, and the coils bolt right to the cover for a cleaner look.

As we said, every torque operation is recorded by the computer and tied to that particular engine. in the event of a failure, this serial number could be input and a complete history of the engine would pop up. in case you're curious, this is the 12th retail-production lS9 ever made. if you're lucky enough to own a ZR1, you can go down to your garage and see if this is your engine in the story. Better yet, have your butler do it.

This gizmo lets the builder install a balancer without breaking a sweat. it uses hydraulic pressure to perfectly install the balancer with a mere push of a button. The next tool (not shown) is a dedicated torque wrench specifically for the balancer bolt.

Every builder takes his job seriously, especially since his name goes on the side of the blower. Of course gM has a tool to help the builder get his nameplate in just the right spot.

With the supercharger installed, the engine is sealed and pressure tested. air is forced into the oil and water passages and the computer makes sure there are no leaks. if the pressure isn't held, the builder has to figure out where the leak is occurring and fix it before the engine can move farther down the line.

Before the builder can torque down any bolt he must first scan the appropriate bar code for that set of bolts. This sets the electronic torque wrench to the proper setting and prevents errors, since the system won't let the builder scan the next fastener until the first ones have been scanned and torqued. all of these torque operations are stored and key the engine's serial number.

At station 10, the exhaust manifolds are installed. These are the same as those used on the lS7. fabricated from 18 separate parts, there's a specific left and right side. To make sure there's no mix-up, they're installed at separate stations-10a and 10B. The racks they're on are color-coded, yellow for the right side, and brown for the left. You can see the new integrated oil cooler mounted to the block.

The flywheel is put on using a two-pass system, and on the final pass each bolt is marked with paint to show it was finished. Notice the nine bolts used to secure it to the crank instead of the six found on an lS7 crank.

The last step for the builder is to weigh the engine. Since the lS9 doesn't have a dipstick, the oil is added by weight so it's important to know what it weighs dry. in our case it was a svelte 530 pounds

After the weight is recorded, the lS9 is tested. first it's run by natural gas so it can be externally balanced. Then it's hooked up to a dC motor and put through a cold test for 45 minutes.

Million-Dollar Baby
When we arrived at Wixom, it was only the second day that engines were being built for retail sale. The day before, six engines were started with the first one-serial number 01-destined for the first retail production ZR1 to be built. That car, which would be built a month later in Bowling green, kentucky, recently sold at Barrett-Jackson for $1 million. Proceeds from the sale will benefit the United Way for Southeast Michigan, so the crazy price is a good thing.

"This is an iconic moment in Corvette and small-block history, and very fitting as we get ready to embark on our company's next century," said Sam Winegarden, executive director, gasoline engine engineering for gM Powertrain. "The LS9 is the embodiment of GM's first 100 years of performance experience and technology, and there is immense pride among everyone involved with its development and manufacturing."

Shown from left are: dean guard, chief engineer, small-block engines; Jeff Stafford, assistant superintendent, PBC; Tom Morrissey, skilled engine builder and builder of million-dollar first ZR1 engine; Ron Meegan, assistant chief engineer, lS9 and lSa; and Mike Siegrist, design system engineer, small-block engines.

When the engines are done, they are double checked and sent offsite for a 20-minute hot test and dyno validation. it takes from 4.5 to 5 hours to build an lS9 at Wixom, which means they can churn out around 45 units a week. Between the nine engines in this picture there's 5,077 horsepower just waiting to find homes in GM vehicles.

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