5.0 Mustang & Super Fords
2011 Ford Mustang GT 5.0 Coyote Engine
For The First Time Ever, The Mustang Gets Its Own V-8-And We Get The Inside Story On Its Birth
Casual enthusiasts will glance at the Coyote intake manifold and think, "Yep, another composite intake." And they might also notice the engine cover is a "picture frame" design, so the intake runners can be seen.
As you might think, there's a bit more to it than that. The Coyote spy shots running loose over the Internet last year showed an aluminum intake manifold, but that was simply an expedient. Early on it was fast and cheap to tool up a handful of aluminum Coyote intakes, but there will never be a production aluminum intake, as all the advantages are with composite. The plastic intakes weigh less, are less expensive in large volumes, and offer dead smooth interior passages compared to aluminum's pebbly runs and casting flash hurdles. Composite does not conduct heat well at all-think of it as an isolator-so a composite intake runs cooler than an aluminum one. Plastic can also be molded in colors, as is the top portion of the Coyote intake.
Mechanically, the Coyote intake is a single-plane. The engineers call it a single-scroll because it is curled up like a snail shell (you didn't think we'd call it a ram's horn, did you?) to fit deep inside the Coyote's valley. The team worked a bit to get the intake plenum far down in the valley to reduce engine height, while simultaneously packaging runners slightly longer and with more gentle turns than those on a Three-Valve 4.6. A major packaging help was routing the coolant crossflow through the block rather than in a separate casting across the valley as with previous modular's.
Tuning on the 430mm-long (16.9-inch) intake tract (from runner entry to the intake valve) is for a 6,500-rpm power peak, the Morse equations putting the second resonance at that point.
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As for that wonderfully centralized front throttle body location, "For years those of us working on Mustangs wanted that center entry throttle. [It was] a major victory," said Mike Harrison. The center entry requires less direction changes for the airflow, resulting in more even airflow distribution. It also gives "half order" resonant frequencies for a more sporting induction sound.
Like the rest of the induction tract, designing the intake manifold relied heavily on Ford's 1D3D CFD software.
An area where the Coyote breaks from the modular pack is its pulse-separated, tubular headers. While hardly the first tubular Ford headers, these intelligently tuned manifolds represent a deep commitment to making power. Doggedly designed, protected from both axe-wielding finance men and dent-prone assembly plants, then nurtured by patient calibration engineers, these headers visibly represent the willing-to-bleed-for-it dedication the Coyote team had toward making power.
Technically, Coyote headers are a short Tri-Y design complicated by the Coyote firing order differing from other Blue Oval V-8s and the need to package the catalytic converters close to the engine. We'll let Adam Christian, the team member who designed these headers, as well as the prototype builder who welded up the prototypes in his home garage, tell the Coyote exhaust manifold story as he told it to us.
Adam started by showing us some test results of the current Mustang GT header. "Here's a comparison of a standard cast manifold like on the Three-Valve 4.6 today, which is a nice design. It was hard to beat those manifolds, actually."
"Headers only give you torque, right? That's in general. And while we wanted torque, we needed to sell the manifolds on power. We had already beat our torque target, so advertised power [was the goal]," Adam explained. "When I left racing [Ford Racing], I told the guy, 'I'm going back to production and I'm taking two things with me: headers and valve lofting.' And at least we got one of them into [the Coyote]. We almost loft-it's really close! We basically go to zero force over the nose, but it doesn't actually come unglued."