Domestic and exotic: The former refers to homegrown fare, but also implies the docility of a family pet. The exotic suggests foreign origins, along with alluring connotations of things that are strikingly and excitingly out of the ordinary. But you know what? GM's spectacular new LS9, the 638hp heart of the upcoming ZR1 Corvette supercar, is a stunning amalgam of both. It's certainly domestic-though you can throw out that whole docile thing-built with an exact mix of handbuilt attention and technological precision at GM's Performance Build Center in Wixom, Michigan. And as for exotica, calling this engine striking and exciting hardly does the thing justice. It is, after all, simply the most powerful production engine GM has ever created. This is our ultimate inside look at this impressive creation: We explored its conception and design and even participated in the meticulous assembly process for one of the very first examples.
In talking about how the LS9 came to be, it's important to remember that nothing happens in a vacuum. It's impossible to separate the development of the ZR1 from the development of the tremendously powerful engine under its hood. In fact, talk of the LS9 started hard on the heels of the introduction of the LS7, then the pinnacle of GM small-block development. What, 505 hp in the hot-handling Z06 wasn't enough? It never is, as Dean Guard, small-block chief engineer and program manager, pointed out. "You don't have to be a fan of Corvette to know more is always better," he observed. "Corvette customers always demand progress, so there's always something on the drawing board."
In this case, what was cooking on the engineers' slates was the "Blue Devil," a prototype vehicle that embodied GM's desire to build an ultra-Corvette that was every bit the equal of Europe's wildest supercars. The key to making it happen was the synergy between the Corvette team and the powertrain team. The challenge to the Corvette team was to make a definitive automotive statement. And for Guard and his colleagues, "Frankly, the challenge to the powertrain team was to deliver ultimate performance." But it couldn't have happened without the ZR1 Corvette. Said Guard: "After all, you can't do something like this and put it on a shelf, right?"
So, on to the heart of the matter: the 638hp, 604-lb-ft LS9. For convenience's sake we'll start at the top, with the prominently displayed Eaton R2300 supercharger running at 10.5 psi of boost through a liquid-to-air intercooler setup. Why a supercharger, we asked? "With the LS7 at 505 hp, that's about all there is," Guard confessed. "With drivability and non-trivial emissions and diagnostic concerns, we had to enter the charged arena." And though Corvette has a turbocharged history with the Callaway Corvettes of yore, it wasn't to be this time. "Supercharging is preferable to turbocharging," Guard explained. "There's better packaging, and it better handles the thermal and emissions challenges." Then there's the availability of the sixth-generation supercharging technology from Eaton. Guard called it simply "the best charging tech available."
Besides the fact that the typical supercharger whine is nonexistent, the powerband is tremendous. GM Powertrain's numbers show the engine as making 320 lb-ft of torque-at only 1,000 rpm. The peak of 604 lb-ft happens at about 4,000 rpm. Most impressively, according to GM, the LS9 is producing 90 percent of peak torque from 2,600 to 6,000. Can you say massive acceleration, anytime? According to Ron Meegan, assistant chief engineer, "The sixth-generation design of the supercharger expands the 'sweet zone' of the compressor's effectiveness, broadening it to help make power lower in the rpm band." This is, of course, done without sacrificing the tremendous high-rpm power the LS9 produces.
What We Did
Got the real story behind GM's most potent engine ever, and helped build one of the first production examples
638 hp and 604 lb-ft backed by a five-year, 100,000-mile warranty
$103,300 for a LS9-powered ZR1 Corvette
Giant leap forward that it is, an amazing 76 percent of LS9 parts are already existing GM
The Performance Build Center in Wixom, Michigan, specializes in producing low-volume engin
Each engine build is accomplished by proceeding though multiple stations, and the parts ne
On the other hand, the LS9's evolution included a softer touch, specifically when it came to the camshaft, which is less aggressive than the LS7's. "According to Uncle Sam," observed Guard, "it's gotta be a refined beast, not just a beast." And this man knows that of which he speaks, since he's been working above and beyond the call of duty by field testing (ie, daily driving) one of the preproduction ZR1s. Of course, one of the most compelling things is that we're talking about 638 hp in a 3,350-pound vehicle. On the other hand, "It's equally impressive around town," Guard reported. "The availability of torque it's there when you want it." We suspect that's a massive understatement.
We asked Guard if the LS9 is able to handle more than the 10.5 psi boost it runs from the factory; he agreed that it was a reasonable theory that some ZR1 owners will be tempted to underdrive the pulley and run more boost. "We didn't probe that," he admitted. "There would probably be some risk there." But that statement belies the mission behind this powerplant: Go get as much power as possible while remaining emissions legal. The team looked at every last part in pursuit of this goal, and Guard concluded that, "We know what we have, and it's very robust." The journey through GM's extensive race track and dyno validation protocols happened-and this is a word engineers seem to appreciate-uneventfully. "We didn't hold anything back, and got where we needed to be," summed up Guard.
Now for the not-so good news, at least for those of you who want to lay hands on GM's ultimate small-block apart from its ber-Vette platform. The Wixom Performance Build Center exists to build engines like this with no-compromise, meticulous attention, and the 25 builders there can produce 45 LS9s per week. It sounds like a lot, but there's already a waiting list for the ZR1, and dealers have more than enough customers to fill their allocation. "I don't think we'll have any trouble getting rid of them," quipped Guard. Given the ZR1's performance numbers-0-60 mph in 3.4 seconds, 0-100 mph in 7 seconds, and the quarter in a smokin' 11.3 at 131 mph-we don't have any doubt of that.
Here's the inside scoop on the most exotic domestic engine going.
The build process relies a lot on computers, but the builders still use old-school methods
At this point, the cam has been installed in the block. The LS9 cam is actually less aggre
GM goes to great measures to make the assembly safer and more ergonomic for the builders a
This device is specific to the LS9 assembly process, and is used to guide the rod into the
...The reciprocating assembly is strong and lightweight, consisting of titanium rods, alon
The LS9 also features this new integrated oil cooler to help deal with the supercharged en
Each station is configured to carry out a specific task, and only the tools needed for tha
As you might expect, GM has a number of specialized tools for assembling engines. There's
One critical issue, of course, was increased stress placed on the top end; the LS9 has to
The cylinder head bolt size was increased from 11 mm to 12 mm, a step that was needed "jus
The head bolt torque operation is of course carefully monitored. If any bolt reads outside
Showing a further refinement upon the LS7 platform, the LS9 uses rails beneath the rockers
Even in this high-tech facility, lots of good, old-fashioned marking paint is used through
Force-feeding duties on the LS9 are performed by a sixth-generation-design R2300 supercarg
The LS9 employs a center-feed fuel line system to ensure even fuel flow between cylinders
With the blower installed and torqued down, the charge air cooler is then installed. The L
The GM Performance Build Center's motto is "One Builder for One Engine," so you can be cer
Once the supercharger assembly is installed, the engine is sealed and pressure-tested. Air
The LS9 uses the same exhaust manifolds as the LS7. These pieces are trick, fabricated fro
The LS9's flywheel is put on using a two-pass system-each is marked with paint on the fina
Speaking of greater clamping strength, the LS9's dual 260mm disc clutch spreads the engine
The last step in the assembly is weighing the engine. Because the LS9 doesn't have a dipst
Each assembled engine is first run on natural gas so it can be externally balanced. After
|LS9 SPECS |
|Displacement ||376 ci |
|Bore and stroke ||4.06 x 3.62 inches |
|Block material ||Cast aluminum |
|Head material ||A356-T6 rotacast aluminum |
|Valvetrain ||Overhead valve, 2.16-inch titanium intake, and 1.59 inch hollow-stem, sodium-filled exhaust |
|Fuel delivery ||SFI (sequential fuel injection) |
|Compression ratio ||9.1:1 |
|Horsepower ||638 @ 6,500 rpm |
|Torque ||604 lb-ft @ 3,800 rpm |
|Fuel ||Premium required |
|Exhaust manifolds ||Stainless steel |
|Crankshaft ||Forged steel |
|Type ||Hydraulic roller |
|Lift ||0.562/0.558-inch intake/exhaust |
|Duration at 0.050 ||211/230 degrees intake/exhaust |
|Supercharger ||Eaton R2300 four-lobe Roots-style displacing 2.3 liters |
|Boost ||10.5 psi maximum |