E-Force Coyote Blower - Force Unleashed
Horse Sense: If you’re interested in a detailed understanding of the new Coyote blower’s background, inspect our Aug. ’09 story on the Three-Valve E-Force supercharger at www.mustang50magazine.com/techarticles/m5lp_0908_edelbrock_e_force_s197_supercharger/index.html. That story has much that pertains to the ’11 Mustang GT kit we’re introducing here.
As we’ve said before, from the instant we saw our first Coyote engine we’ve been excited by the thought of supercharging it. And sure enough, to date the blowers we’ve sampled on the ’11 Mustang GT have been successful, to say the least. Even better, we’re happy to be back reporting on another winning Coyote blower aimed at real-world Mustangs.
This time it’s aftermarket giant Edelbrock that has fitted its E-Force positive-displacement supercharger to the Coyote. In a few words it’s an excellent real-world combination. The performance is strong and the support what you’d expect from a large company such as Edelbrock. Certainly the Big E will take a front-row position in the ’11 Mustang GT owner’s list of supercharger options with its new offering.
To save you from thumbing to the back of the article, we saw 466 rwhp on Edelbrock’s chassis dyno in stock kit form—that’s at just 4.5 pounds of boost and breathing through the stock airbox and throttle body. On Edelbrock’s engine dyno the numbers were 575 hp with a 1/4-inch-smaller pulley, and 636 hp with the same smaller pulley and a less restrictive inlet. To put that in perspective, with about 3 pounds less boost, the Edelbrock Coyote makes the same power at its tires as an Edelbrock-assisted Three-Valve does at its flywheel. Another way of looking at it is the Coyote gains 120 hp at its tires with the stock Edelbrock kit. It’s enough to make you want to howl.
Rob Simons is Mr. Supercharger at the sprawling Edelbrock HQ, and after our coverage of the Edelbrock blowers for the Three-Valve S-197 Mustang, he figures the Coyote version is pretty easy to understand. That’s because the ’11 Mustang GT E-Force blower and the Three-Valve version differ only in the blower’s runner length, throttle body, front drive section, drivebelt and pulleys, and, naturally, the tuning.
On the other hand, the new blower’s basics are easy enough to understand even if you’ve never seen the Three-Valve variety. It all starts with the well-regarded TVS rotors supplied by original-equipment supplier Eaton. These twisted Roots-style rotors are designed for Eaton’s original equipment business and whittled out by sophisticated CNC machines, so they are durable, quiet-running units. In fact, they are the same rotors as used on Roush Mustangs and ZR-1 Corvettes.
Edelbrock makes everything else, casting its own supercharger housing, manifolds, runners and so on. The Edelbrock design places the supercharger low in the engine’s valley, blowing upward through an air-to-water charge cooler. The charge air then turns 180 degrees, dropping nearly straight down 15-inch-long runners and into the cylinder heads. This hides the blower under the intake manifold, so the supercharger is not immediately apparent visually with the view being dominated by the intake runners.
Those long intake runners are a focal point of the E-Force blower and aren’t there by accident. In short, the runner length aids breathing in the 2,500 to 5,500 rpm range by taking advantage of a pressure wave keyed by the intake valve opening (Edelbrock knows about such things). This is in the prime street rpm range, promoting respectable off-boost torque and fuel economy, a muscular midrange, and streetable top-end power.
Yes, these runners are also an airflow restriction at high rpm and boost levels, but we doubt the effect is of any practical concern at non-racing boost levels. In any case, the torquey long-runner design is well matched to Edelbrock’s target of street-friendly performance and slightly lowers the heavy supercharger to preserve handling.
Another long-runner characteristic is lower-than-expected boost, the E-Force/Coyote making a nominal 4.5 pounds compared to the E-Force/Three-Valve combination, which is more of a 6- to 8-pound operation. As Rob puts it, “With the longer runners, the manifold is ‘tuned’ for an rpm range of 2,500 to 5,500 rpm, so while in this operating range, the boost pressure will be much lower, for a given air flow rate … The traveling wave is helping to evacuate the plenum more effectively, thereby lowering the restriction, thereby lowering the boost pressure. At high rpm, that advantage goes away, and you see the boost begin to rise. It is a trade-off. We believe that the majority of driving is done in the 2,500- to 5,500-rpm range, so we chose to tune the runners for that range.” And that is why the E-Force makes happy power at just 4.5 pounds of boost.
As with all E-Force superchargers, this blower breathes from the front. This gives a short, direct air path and packages easily under the Mustang hood. Because the Coyote throttle body is already a generous 80mm, it is retained with this E-Force blower.
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