Ever-better cars from Chevrolet can be a two-lane road for Corvette fans–the thumping power, sharper handling and sophisticated design is wonderful straight off the showroom floor, but it makes improving the stock package that much more difficult. Chevy picked all the low-hanging performance fruit years ago, so there are few bolt-on performance mods worth the effort.
There is, however, one very significant bit of hot rodding left in the motivated enthusiast’s toolbox: supercharging. Unlike most engine mods that toy with an engine’s power curve–give a little here to gain some over there–a positive displacement supercharger yields a fundamental power gain all the way across the tach. Packing more air and fuel into the cylinders is where the rubber meets the road in power building, and that’s exactly what a supercharger does.
Noteworthy to proud new C7 owners, Edelbrock has developed their blower to fit the newest Corvette. Available in manual and automatic transmission trim, the new Edelbrock kits are built around their usual, durable rotor pack and, following Edelbrock practice, they’re totally complete. Thorough engineering has made the kits a simple, nearly pure bolt-on, plug-and-play installation, with everything fitting beneath the stock hood.
In fact, the Edelbrock blower looks and drives as if it came from Chevrolet. The underhood presentation is OEM, with minimal “Edelbrock” signage to announce the blower packaged low in the engine’s valley; it’s even styled to mimic the stock engine cover. All hoses are accurately molded, electrical connections are proper plug-in connectors, and overall it gives the impression that the installation could have come from Bowling Green.
The factory feel continues on the road. After sampling the Edelbrock blower on a black Lingenfelter C7 with a manual transmission, along with Edelbrock’s own red C7 automatic, we can report the power is immediate, generous, and rather addicting. Triple digit speeds are an off-hand achievement involving a single gear change, so budgeting some track time to fully explore the newfound thrust is the right way to get acquainted with the 624 flywheel-horsepower this kit produces on 91-octane pump gas.
Furthermore, there’s no gear whine or wind whistle, so off-boost, your new ‘vette drives just like your new ‘vette should. Mat the loudpedal and the blower gives a satisfying whoosh and a distant shriek that put some extra fun into the proceedings—as if any more was needed—but there’s no screaming siren.
Photos by Tom Wilson, courtesy of Edelbrock Corporation.
Engineering The Edelbrock–C7 Combination
Interestingly, much of Edelbrock’s 2014 Corvette kit was jump-started from their Chevy Silverado 6.2-liter V8 truck kit that was started a bit before Chevy debuted the new Corvette.
As always, Edelbrock engineers began with the Twin-Vortices System (TVS) rotor pack. This specialized, high-precision assembly is sourced from the Eaton Corporation, who also supplies the same rotors in various displacements to Mercedes Benz, Jaguar, and other car makers. Edelbrock then engineers and manufacturers the rest of the blower, manifolding, and installation kit, starting with the supercharger case the rotors run in.
A distinguishing feature of Edelbrock superchargers is the drive shaft that runs through the nose of the case. This is for ease of packaging, and allows for a shorter, more direct air path from the air filter through the throttle body and into the supercharger. As expected, this layout was fitted to the 6.2-liter Silverado engine, then carried over to the Corvette’s LT1.
Another given with Edelbrock superchargers is the blower fits in the valley of vee engines and discharges upwards. The warmed charge air leaves the blower and the first thing it runs into is the top of the blower case, where it disperses to either side, turns downward, and then passes through one of two charge cooler (intercooler) cores.
After shedding some heat to the cooler cores the air continues downward through very short intake runners and into the cylinder head intake ports. This packaging is very space efficient, especially vertically, even if it doesn’t visually highlight the supercharger when you open the hood.
The short intake runners are there only for packaging and offer no intake tuning in the traditional naturally-aspirated sense. This might sound like a lack of torque when off-boost, but with variable cam timing and 6.2 liters of displacement, you don’t feel deprived! And obviously there are oceans of torque when on-boost, so lack of oomph is never an issue.
What had Edelbrock engineers chewing their pencils was if the blower and manifolding would fit under the very low Corvette hood. Knowing they would eventually be tasked with fitting their blower to the upcoming Corvette, when laying out the Silverado kit, the engineers had sunk the supercharger as close as they dared to the high-pressure fuel pump in the engine valley and let the rest fall where it would. But not until the new Corvette went public could Edelbrock know if they had gotten it low enough for the new Stingray.
They got their first look at the C7 ‘vette during Chevy presentations associated with the Pebble Beach Concours and historic car races at Monterey in August of 2013. The Edelbrock engineers made a special trip to the big show just to measure a C7 display chassis shown there in hopes a bit of tape measuring would reassure them their supercharger was low enough. Much to their relief, it was.
It’s both ironic and illustrative that the engineers reverted to tape measures to check their work, as the C7 kit was designed solely from CAD files. That is, Chevrolet supplied Edelbrock with digitized files of the stock LS/LT engines, plus the Silverado and C7 engine compartments, allowing Edelbrock to plug the data into their computers in Torrance, California, then confidently fit the supercharger to the engine using their own blower’s digital form.
This was the first time Edelbrock had designed a complete blower kit electronically, without benefit of a car or prototype blower parts. The entire kit was created digitally, including the belt drive, manifolding and other accessories.
The only trick was Chevrolet’s C7 CAD files didn’t arrive at Edelbrock until after the 2013 SEMA show last November. Thus, the initial reliance on the truck kit, and the very preliminary, proof-of-concept nature of the blown 2014 ‘vette Edelbrock showed at SEMA
That effort required a one-off rapid-prototype aluminum blower housing/intake manifold assembly that could withstand a bit of dyno duty. It was printed by an outside contractor while several composite rapid prototype blower cases and small parts were printed in-house by Edelbrock during kit development. But that was it for prototype parts; the rest was all done digitally.
Chad Magana, Senior Design Engineer, and Jon-Eric Gonzales, Design Engineer at Edelbrock, worked out the details of the 2014 Corvette kit in conjunction with the firm’s quality control and manufacturing engineers. Magana was mainly responsible for the rotor housing, intake runners and nose case while Gonzales concentrated on the belt drive, side covers and inlet tube.
As always, a few details required most of the creative thinking on the 2014 kit, according to Gonzales. One of those was the coolant crossover tube. As part of an ongoing goal at Edelbrock to reduce the complexity of each successive blower installation, the four inlet and outlet charge cooling coolant tubes as seen on the SEMA prototype were reduced to two tubes—a lighter, neater, less costly solution.
Something of a surprise was the belt drive. While a longer serpentine belt to drive both the stock engine accessories and the supercharger was the first choice, it turned out a belt of sufficient strength and correct length was not available, so a dedicated 10-rib blower drive was developed. The self-cleaning, 10-rib Goodyear Gatorback is admittedly overkill, but as supercharging specialist Rob Simons, Vice President of Research and Development at Edelbrock, points out the premium belt will easily last 100,000 miles. Call it a lifetime.
An advantage to a 10-rib belt is that it requires less belt tension for reduced drive loss. Another is that it puts less strain on the harmonic damper because the belt tends to stay in contact with the damper, rather than lifting and snapping into engagement as a narrower belt might do during sudden rpm changes. Such an incident could eventually cause a casualty of the rubber isolator between the damper’s inner and outer rings—never a pretty thing. Thus, a moderate force Dayco belt tensioner was selected; it mounts using existing bolts so no drilling or tapping was required. Furthermore, all stock engine accessories remained as-is in their stock locations.
Edelbrock had damper specialist BHJ develop an SFI-approved crankshaft damper for this kit. It used a separate pulley for the blower drive so the damper need not be disturbed during any future pulley changes.
And there are plenty of pulley options. Edelbrock offers blower pulleys ranging from 4.125-inch (low boost) down to 2.75-inch (high boost) in .250-inch increments. Additionally, for the C7 Corvette kit there are large (8.750-inch) and small (7.327-inch) crankshaft pulleys. The kit comes with the small crank pulley, which is the same diameter as the stock Chevy pulley but is 10-rib to work with the wide belt, along with the 3.500-inch blower pulley to arrive at just a hair under 6 pounds of boost. Varying from this voids the Edelbrock warranty, but if that’s not a worry, there are plenty of boost-making pulley options.
Another improvement is an all-around larger capacity charge cooling system. It’s something Edelbrock has been wanting to do for a while, and it starts with larger charge cooler cores compared to the C6 kit. There are two of these cores flanking the supercharger and cooling the post-blower intake air. Mainly, the new cores are larger on this kit than previously, so they are more efficient, absorbing more heat from the intake air while offering only a minor increase in air resistance.
At the other end of the charge cooling system is the LTR, or Low Temperature Radiator. That’s the heat exchanger mounted low, behind the Corvette’s grille to dissipate the charge air heat to the atmosphere. To match the greater heat absorption of the larger charge cooler cores, the LTR is also slightly larger on this kit than on the C6.
Circulating the coolant is a higher capacity pump. Edelbrock points out they have been using the industry standard 5 gpm Bosch pump, but the new pump is brushless, pulse-width modulated, and moves about 40 percent more coolant. Finally, the charge coolant tank is about three times larger.
Because Chevy is engineering the basic 2014 ‘vette to support future power increases with large fuel lines, high-capacity fuel injectors, and a healthy 60 psi pump in the fuel tank, Edelbrock needed to do little to supply adequate fuel to their supercharger. The only hardware change in the fuel system is substituting a hard fuel pipe extension for the flexible fuel hose atop the engine where the fuel supply catches up to the high pressure fuel pump. This is a simple packaging and installation consideration.
Ultimately, the power limit in the fuel system is Chevy’s high-pressure direct injection fuel pump. It lives between the cylinder banks in the bottom of the vee and is driven by a large lobe on the camshaft. It jacks the fuel pressure to a minimum of 1300 psi at idle and 2175 psi at maximum power. So, even if you could, increasing the fuel pressure a few pounds isn’t going to support more power—more fuel volume is the need.
Edelbrock dyno testing confirmed the stock pump starts lagging at around 630 lb-ft of torque, and to give their warranty a little margin they’re holding the engine to 600 lb-ft of torque with the standard blower pulley. This is a happy bump up from Edelbrock’s 2005-2012 Corvette blower kits with the optional upgrade package. Those delivered 599 hp and required an expensive aftermarket fuel pump that’s tricky enough to install–so much so that Edelbrock calls it a pro job.
Edelbrock is loosely contemplating a 1,000 hp version of the C7 kit, and should they decide to build such a thing, it will require a greater capacity direct-injection high-pressure fuel pump, not to mention a tougher shortblock. But then, speed costs money, so you have to decide how fast you want to go.
Electronically, Edelbrock supplies an SCT Performance XCT X4 color-screen programmer to plug into the C7’s OBD port. Of course a pre-programmed tune is included for instant gratification once the blower is bolted on; and there’s no reasonable need for any other tuning. Unless, of course, you further modify your ‘vette, and then the X4 can handle that, too. The pre-programmed tune is for 91-octane fuel, and by the time you read this the kit should be 50-state legal (with a CARB E.O. number).
Also worth noting, the manual and automatic supercharger kits are identical from a hardware standpoint, differing only electronically. Edelbrock is also supporting the dry-sumped Z51 option, and it differs from the wet sump manual/automatic trans versions only by way of a different harmonic balancer.
That leaves the price of all this fun. Retail is pegged at $7,495 by Edelbrock. Unlike the C6 kit, installation can by done at home, or pencil in a little less than $1,000 for a pro install. As for where to buy these kits, Edelbrock’s distribution is excellent so anywhere from AutoZone to JEGS and seemingly everywhere in between can order them.
To veteran observers, Edelbrock’s newest supercharger kit is amazing in its sophistication and completeness. Cars have become more complicated and efficient—and by extension more difficult to tune—yet here is an aftermarket giant significantly raising the OEM performance bar. Edelbrock’s complete integration of CAD design and growing embracement of rapid prototyping complement their earlier investments in high-volume CNC machining and a foundry.
The result is a Corvette supercharger that elevates the base car to nearly ZO6 power with ease, style, and a warranty. In other words, for the new Corvette owner looking for supercar power devoid of any hassle in his daily driver, Edelbrock has an answer.