Cylinder Heads
Ford’s Ti-VCT Coyote has a new cylinder head design that makes the engine less bulky while providing extraordinary high-RPM breathing. The Ti-VCT’s intake ports are free from restrictive tendencies, outflowing even some of the most legendary racing cylinder heads in the industry. Intake flow numbers are in excess of 300 cfm. Because the Coyote’s top end was designed more as a package than just individual heads, cams, and induction, it produces numbers never seen before in a factory Mustang engine. These heads flow very well without specialized port work, which leaves the door wide open for even more power if you decide to do port work.
The Coyote head is clearly different from the 4.6L/5.4L 4V and is not interchangeable. In front are provisions for the chain tensioner and Ti-VCT feature, which are oil-pressure controlled. As you can see, the cam journals are generously lubricated and the oil galleys are easily accessed. It also has a water jacket freeze plug.
With the left-hand cylinder head in place, identified with an “L,” it’s challenging to see where the head ends and the block begins. The Coyote is a well-thought-out package, where block and head become one. The objective was to come up with a lighter, smaller cylinder head to get unnecessary weight out of the Mustang while conceiving a more swappable engine that can fit more applications. This is how you design and produce a factory high-performance engine.
This is the right-hand (passenger) head, with an “R” (for “right”) and the Ford casting number. At least four cylinder-head castings are available at press time: 2011–2014 standard head, 2012–2013 BOSS 302, 2015–2016 CMCV, and the GT350 head.
Closer inspection shows the great advances of the Coyote’s valvetrain system. The valve angle has been modified for improved flow, and valvesprings and retainers are smaller and lighter. In fact, you may opt for lightweight springs and titanium retainers for even greater freedom. The oil drainback is greatly improved.
The Coyote’s 57-cc four-valve hemispherical chambers demonstrate how different these heads are from previous Modular castings. Four valves per cylinder were surely a given with a performance engine such as this. However, in order to move the intake ports away from the crankshaft centerline and decrease cylinder head width, the valve angle and distance between valves were revised significantly. This revised geometry allows for more valve lift without the risk of valve to piston contact. The intake valves are 1.460 inches in size; exhaust valves are 1.220 inches. The spark plug firing tip is in the middle of the chamber.
Ford’s Ti-VCT design team, specifically Todd Brewer and John Reigger, understood it would have to spend a lot of time to come up with a cylinder head that could do everything. First, they had to perform basic hotrodding tricks to achieve greater flow; then, these seasoned engineers had to jump into areas that they had never ventured into before. Although the Coyote cylinder head appears to be a derivative of the GT500 head, it isn’t. A lot was learned from the GT500 head, yet none of it was carried over.
Engineers had to focus on aspects of port design that had never been considered, such as the distance between the four valves, valve angle, valveseat revisions, and more. Valve angle had to change to improve valve to piston clearances and air flow. Thanks to advanced computer technology, engineers were able to come up with a new cylinder head quickly. It took extensive development work for six months at seven days a week to create a new, more innovative head.
When Team Coyote was finished with basic cylinder head casting development, it had to go back and look at cam profile along with valvetrain size and weight. Think of high-revving motorcycle engines; this is what Ford was faced with in developing the Coyote. Rocker arms and valvesprings had to be much smaller to improve both efficiency and performance. There had to be less reciprocating weight to enable these high revs. Put the 4.6L/5.4L and 5.0L rocker arms side by side and you see the difference in size. The 5.0L engine does it with less mass and weight. In addition, it enabled Ford to reduce cylinder head size and width, which reduced overall engine width.
The Coyote’s valvetrain system is the most complex cam and valvetrain package ever installed in a Mustang, and it is designed to optimize all driving conditions. This task went to Kevin Shinners and Adam Christian, engineers who developed the camshafts and valvetrain. “Ti-VCT” means “Twin Independent Variable Cam Timing,” which in turn means that the intake and exhaust cams work independent of each other based on driving demands. Each camshaft is indexed or phased around its centerline by oil pressure. Oil pressure is metered electronically via solenoids and phasers to control cam indexing as required.
The Coyote’s valvetrain has been made smaller for reduced weight and size. These are two of the Coyote’s four composite camshafts. The intake valve lift is .472 inch; exhaust valve lift is .432 inch. The greatest lift these cylinder heads tolerate in stock form is .512 inch, which is more than enough for the average street and strip car. The intake duration is 260 degrees, and the exhaust duration is 263 degrees.
Each camshaft reluctor works hand in hand with a cam sensor tied to the PCM (Powertrain Control Module). Pulses from each reluctor tip signal the PCM, which helps calculate engine speed, injector pulse width, spark timing, and more, which makes the Coyote the most precision-controlled Ford engine ever.
Ti-VCT enables the Coyote to deliver an incredibly wide power band across RPM ranges while giving you the bonus of high-end horsepower, which was not previously easy to achieve. What makes the Coyote’s Ti-VCT different from the rest of the Ford line is cam torque actuation, which uses valvespring energy to advance and retard timing more quickly depending on engine RPM and driving demands. Instead of a complex electronically controlled shuttle valve and oiling system routing, the Coyote’s Ti-VCT is a simple on/off solenoid; cam torque does the rest.
Ti-VCT can advance/retard valve timing by as much as 50 degrees, and do it in .2 second. This approach offers you modest valve timing on the way to work and more aggressive valve timing when it’s time to get the heat on. For the environmentally conscious, the Coyote doesn’t need EGR (exhaust gas recirculation) because valve overlap is increased in certain types of driving, especially deceleration, which reduces hydrocarbon emissions.
At the front of each cam is this journal, which carries the Ti-VCT articulating cam sprocket, or phaser, which advances valve timing as necessary based on driving conditions and demands. Oil pressure is routed through the number-1 cam journal and each solenoid. Four solenoids are present: one for each camshaft. Each solenoid controls oil flow to each cam timing phaser, which moves each camshaft around its axis.
