Inside The Belly Of The Beast
PHR goes inside GM's high tech performance build center to assemble an LS7
By Steven Rupp , courtesy of GM
Photography: Steven Rupp
True gearheads, who work for magazines, live for one thing, getting the inside scoop on the "next big product" to hit our hobby. So when GM sent out the invite to come wrench together a new engine the answer wasn't just yes, it was "hell yes!" And, it turned out this wasn't just any old motor from the General, but the most high-tech engine every produced by GM, the 500hp LS7.
It so happens that GM is understandably proud of their newest mill and of the talented people that are going to make it happen at their new, state-of-the-art 100,000-square-foot Performance Build Center in Wixom, Michigan. The program included flying out various magazine guys for a day of automotive nirvana. We would work with the GM master builders to assemble an LS7 engine. From start to finish we would build it in exactly the same way it will be done in full production. Having worked on a few LS1 engines I was very interested to see what was new with the LS7 and also how it compared to the recently released LS2 engine.
Here you can see the finishing touches being put on a new LS7. But, how does GM get to this stage? Well, follow along as we take go step-by-step through the LS7 build process at the GM Performance Build Center.
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The blocks that arrive from the suppliers are supposed to be clean, but GM powertrain washes down the motors just to make sure. Any contaminates are caught in a filter and used to monitor the supplier. After this initial washing, the blocks are placed in this pressure-wash booth, blasted spotless and then air-blown dried.
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After the wash process, the engine is assigned its unique bar code labels. This identification number will be referenced throughout the build process. Here you can see the build sheet that will follow the LS7 through the assembly stations.
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Engine assembly is divided into stations where the various parts are installed and tested. At each station the engine parts for the specific process and the tools for doing the particular job are pre-staged. Kitting trays are used to hold every part that is going to be used at that station. This ensures that a part is not missed. Every torquing operation has a bar code and a computer adjusts the electric torque wrenches based on the bar code for that specific operation. The computer also tracks how many bolts are torqued. This ensures consistent quality and also makes sure a bolt isn't skipped. At Station One the pistons are checked, caps are marked for position and caps are pulled. This is also where the bearings are installed.
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With camera in hand and a notepad of paper, I arrived that the GM Performance Build Center in snowy Wixom. The day started off with a bonus, a discussion about the other motor that will be hand assembled at the new plant, the supercharged Northstar. An entire article could be devoted to the massive amounts of technology in this new caddy motor, but let's just say that it is an amazing piece of engineering. We were then given a PowerPoint show about the history of GM engines and the success they have enjoyed in everything from drag racing to NASCAR. Tom Stephens, GM group vice president, GM Powertrain, briefly touched on the enormous power being made by the V-6 and four-cylinder Ecotec motors. We learned from GM Performance Parts that the LS7 would be available as a crate motor sometime this summer, but a price was not yet available. At least for the foreseeable future, the crate LS7 will carry the titanium rods. Also, since the oil system is integral to the design of the engine, the LS7 crate motor will be a dry sump motor. In essence, the engine will be exactly like the one they will be shoehorning into the new Z06.
As detailed in our April 2005 LS7 story, it is important to note that the LS7 is a completely different animal than the LS2. This is not like the relationship between the LS1 and LS6. To get the required performance GM took a "systems-wide" approach in building the LS7. Many of the parts vary greatly from its LS2 cousin. The dry-sump system is a work of art and should actually make retrofitting one into some old musclecar easier due to its slim profile. While the titanium rods are expensive, they are necessary to allow the motor to reliably push 7000rpm on a regular basis. The heads are massive and are not only equipped with titanium intake valves, but have been heavily ported out as well. The LS7 is basically a race-quality motor for the street and it is assemble in a very meticulous fashion. Each LS7 is hand assembled by one of the master assemblers at the plant who takes personal ownership of the motor from start to finish and, in a nice touch, has their nametag on the finished product. Sure the crate motor will not be low buck but considering the technology employed in it the value is certainly there.
Oh, and when I say an LS7 is "hand assembled" don't get the idea that this resembles the way average people would put an engine together. Every operation is data-logged though the use of computers and bar codes. Bolts are torqued using electric, computer-controlled torque wrenches while some parts are installed using hydraulic pressure. At the end of the build, the actual torque spec of every bolt on the engine can be looked up in the computer. We were told that during actual production, if a critical part of the motor is dropped, like a main cap, then the entire block is sent to scrap (I would bet they guard the dumpsters so don't get any ideas). This combination of craftsmanship, technology and strict quality controls will allow GM to turn out a very consistent and very reliable engine. It takes an expert at the Wixom plant four hours to assemble a LS7 engine and plant capacity is about 30 engines per a week. We noticed that there is ample room in the plant to add another assembly run in order to increase production to 45 engines every week. With that, lets start putting one together.
Station two is where the camshaft is installed. The plant uses many specialized tools to ensure the highest quality and consistent builds. For the cam a special guide is attached to the end of the cam to help guide it through the block. All parts are oiled using only Mobil1 oil. A nylon keeper is then attached to the back of the block to keep the cam in place and the cam retainer plate is installed on the front of the block. The block is then put on a rolling engine stand, rotated and the LS7 valley cover is installed. After the oil-galley plugs and lifters are installed the engine is rolled to the next station.
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Here is one of the electric computer controlled torque wrenches used throughout the build. Scanning a bar code for a particular operation sets the wrenches torque and the computer records what that bolt was actually torqued to. The tool took some getting used to, since there is no traditional clicking noise made. When the proper torque has been reached a green light comes on. If there is a problem a yellow or red light illuminates. |
Here you can see one of the bar code sheets. It tells the assembler what size socket is needed for any operation and scanning the corresponding bar code sets the torque wrench for that specific value.
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The forged crank is installed at station three. Cranks are not lifted by
hand but rather moved by an electric hoist specific for this operation. This not only prevents damaged parts from a dropped crank but also stops injuries to assemblers. The caps are now installed taking care to make sure they are put in right position and that they are facing the right way. This is also where the thrust bearing is set. The crank is spun to make sure it moves freely. |
Station four is where the LS7 gets its pistons. The cylinder is oiled and then the piston is inserted into a tapered sleeve. A slight rap from a nylon hammer sends the piston into its new home. This tapered sleeve made it extremely easy to install the pistons. Do this seven more times, install the rod caps and you are done. Well almost. After the eight pistons are installed a computer tracked torque wrench turns the crank and the resistance is measured. This makes sure nothing is binding up and that everything is moving freely. |
Here is a great shot of a typical kitting tray and tool tray. As you can see every tool needed for assembly is neatly arranged and each part needed for that particular station has a molded spot in the tray. When your tray is empty then all your parts have been installed. We should all be this organized. |
At Station five the LS7 gets its crank sprocket. In order to avoid damaging the thrust bearing by hitting the sprocket onto the crank, GM uses 2000-psi of hydraulic pressure to install the sprocket onto the crank. Next the motor gets the cam sprocket, timing chain and the nylon chain dampener. As we talked about in our April LS7 engine story the LS7 uses a specific duel impeller pump. It is actually two pumps in one and handles engine oiling and scavenging duties. The impeller notches have to be lined up, again they have a custom tool for this that you can see in the picture. |
Here you can see the fixture plate that is used to make sure the oil pump and front cover are both perfectly even with the bottom of the block. You can also see one of the many nylon bolt-order templates that are used throughout the build at different stations. After every operation an orange mark is made on either the part or on a specific location on the outside of the block. It's just one more way to double check that nothing is missed. Next up the dry-sump oil pan is installed. The pan is an engineering marvel and makes for a very low-profile package. Installing this in a g-Machine should not be very hard. However due to the way the pan is made there will beno notching of the pan possible. The LS7 also uses a new internal bypass oil filter (PN PF48). |
Those amazing CNC ported LS7 heads are installed at station six. The multi-layered Steel (MLS) head gasket is installed and the head put in place. At this time the most amazing tool I have ever seen is used. This thing torques down all 15 bolts in one single operation! If any of the bolts, for whatever reason, does not torque down to spec then a red or yellow light indicates its position. It literally took less than five minutes to install a cylinder head, you too can have this productivity in your garage. Just shell out a couple of hundred thousand bucks and your set. This is also where the engine identification bar code sticker is actually placed on the LS7. One is placed on the front and one on the back of the left cylinder head.
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At station seven the LS7 starts to get all its external parts. First the valve covers are installed along with the steam vent tube and blockoffs. Then the LS7 specific composite intake manifold, they call it an Integrated Air Fuel Module (IAFM), is installed. The intake comes from the supplier with the injectors, fuel rail and throttle body already installed. Next up the motor gets its coil packs, water pump, temperature sensor and plug. The LS7 is checked to make sure the friction washer is installed, remember that the balancer is not keyed, and then the harmonic balancer is pushed onto the crank using 3000-lbs of hydraulic pressure.
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Station eight has us installing the LS7 specific exhaust manifolds. It is also where we installed the block-mounted knock sensors and the colder running LS7 plugs. A temporary blue cap is put on the valve cover where you would normally put oil in a LS2 engine. Later, once the engine is filled with oil the first time at the run in center, the blue cap will replaced with a locking plug. After this, oil for the LS7 can only be added to the dry sumps oil tank. Each station has visual-aid sheets, like the one above, to be used for reference by the assembler. The sheet also gives information on what to check on each part and anything else needed to insure a proper build. |
At station nine the engine is finished off with the addition of the evaporator
solenoid. To make sure the engine is sealed up tight all the openings are sealed up and the engine is pressurized. Two-psi of air pressure is put in the oil and combustion areas while 20 psi is put into the water system.
This pressure must be held by the motor for given amount of time. If there is a leak it is tracked down and fixed. This ensures that the motor will
not have a leaky exhaust manifold or worse. Once it passes this test the plug wires, evaporator lines and the cam sensor are attached. Herce you see our assembled LS7 engine complete with the green lifting brakets.
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To show the pride of ownership that the master assemblers have, a "built by" plaque is attached to every LS7 produced. If you see this particular name on your motor you might want to visit your dealers service center as soon as possible. All the assemblers I met were true "car guys" that are very passionate about what they do. Many of them had pictures with them of the cool rides they work on at home.
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The last station is number 11. This is where the motor is ran for 30-40 seconds using natural gas and then a computer tells the operator where to place small weights on the flywheel and/or the harmonic balance. After this balancing operation the LS7 is sent over to Johnson and Murphy in Taylor, Michigan, where it is ran for 20 minutes. They run the LS7 for 10 minutes unloaded and 10 minutes loaded. It is here that horsepower, torque, oil pressure, fuel pressure and all functions are rechecked. This is done with the same ECM that will be in the car and is done to every single LS7 produced. |
Sure they are empty now but sometime in April they will start filling up with thousands of horsepower worth of LS7 motors. Most of these LS7 will be sent to Bowling Green, Kentucky. The rest will find their way to GM performance Parts where you will be able to buy one of these exotic engines for your very own g-Machine project. |
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06-16-2005, 01:50 AM
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