The triumphant return of Ford’s fabled 5.0-liter engine, know affectionately as the “Coyote,” is widely considered nothing short of a modern day automotive engineering marvel. Perhaps one of the greatest attributes of the new engine design that’s carried the new 5.0L to ‘legend status’ after just a year on the market has been its all-new 4-valve, dual overhead cam design. With four outboard camshafts – two intake, two exhaust – and the first V8 application of cam torque actuated Twin Independent Variable Cam Timing (Ti-VCT), the Coyote exhibits sky-high RPM capabilities that will get any Mustang enthusiast salivating.

COMP Cams was the first camshaft manufacturer to exploit the impressive new valvetrain design of the Coyote by releasing the first full-production aftermarket cams designed specifically for the 5.0L Modular engine, StangTV, along with Brent White and company at Brenspeed, recently took a closer look at COMP’s new 5.0L pieces and put them to the test. In this tech article, we’ll chat with COMP’s Matt Patrick as we dig into the finer details of the Coyote lineup from COMP, discuss how they coincide with Ford’s Ti-VCT, and deliver the dyno numbers as we install COMP’s Stage II naturally aspirated camshaft kit in one of Brenspeed’s 2011 Mustangs.

COMP’s 5.0-Liter Lineup

Along with the rest of the Mustang community, we got our first glimpse of COMP’s new 5.0L Coyote camshafts at the SEMA Show in Las Vegas in November.  As COMP’s Gary Bruce explained to us at the time, these are a brand new design of cam castings – meaning they aren’t simply reground cores – with counterbalance weights built into the camshafts to cut down on vibrations and harmonics for a smoother-operating valvetrain. Combined with the award-winning (and required) new phaser limiter and phaser lock kits, the variable valve timing can be limited or locked down depending on the intended use of the vehicle, be it race or street duty.

COMP Cams' new XFI NSR camshafts were the first aftermarket cams designed from the ground-up, specifically for the new 5.0L Coyote engine. The phaser limiters (pictured) and phaser locks used in conjuction with these cams earned awards upon their unveiling at the 2010 SEMA Show.

Comprising COMP’s XFI NSR lineup of cams are six different kits for the 5.0L 4-valve Modular, with three stages being offered for both forced induction and naturally-aspirated engines with optimized profiles for each. The “NSR” in the product name signifies that aftermarket valve springs are not required, reducing the expense necessary to make a cam swap in your Mustang.

“A lot of the lessons that we learned with our 3-valve program were put into effect on these new camshafts for the 4-valve, and the biggest thing in our mind is releasing the ‘no springs required’ cams right off the bat,” explains Patrick. “In the past, we’ve gone full tilt and created a high-end design, changing the springs out, and cranking it up to make as much power as we can with a given spring package. But we learned with the 3-valve cams that springs are so difficult to install that what may have been a $1,000 job to have a cam installed became a $2,500 bill with the labor involved. We realized that it may be a good idea to manufacture a drop-in camshaft initially and see how they perform, and in the future, if there’s a demand for it, develop a higher lift, higher performing cam.”

Taking into account the wishes of their customers, COMP designed the XFI NSR cams as drop-in, upgrade camshafts that don't require aftermarket valve springs, making a cam swap quick and affordable.

These billet hydraulic roller cams unlock some great performance from the Coyote powerplant, with COMP Cams advertising between 30 and 40 horsepower gains on stock (or near stock) engines from the upper level Stage III cams. With the DOHC cam design, the 5.0 is capable of normally operating over 7,000 RPM and with BOSS 302 intakes installed, have even been known to border 8,000 RPM. The cams in the Coyote are larger than any other cam-in-block engine, and due to their large size, create dangerous harmonics. However, the XFI NSR, which are advertised with an operating range upwards of 7300 RPM, use the counterbalance design to ensure a valvetrain with long lift and long duration valve motion at high RPM.

“Our customers really desired drop-in cams with good power gains, but that didn’t require changing of the valve springs, and so that’s what we focused on this go-round,” says Patrick. “We have three stages of cams, ranging from a street/strip model to a big drag race type cam, which is still pretty streetable. We feel that this lineup provides our customers a nice option to choose from without costly or time-consuming spring changes.”

XFI NSR Cam Specs:

Naturally Aspirated Cams

  • PN 191060 – Stage I – 220 intake, 223 exhaust .492 intake and .453 exhaust lift and 126 degree lobe separation
  • PN 191100 – Stage II – 228 intake, 231 exhaust .492 intake and .453 exhaust lift and 126 degree lobe separation
  • PN 191160 – Stage III – 236 intake, 239 exhaust .492 intake and .453 exhaust lift and 126 degree lobe separation

Blower Cams

  • PN 191260 – Stage I – 220 intake, 227 exhaust .492 intake and .453 exhaust lift and 128 degree lobe separation
  • PN 191360 – Stage II – 228 intake, 235 exhaust .492 intake and .453 exhaust lift and 128 degree lobe separation
  • PN 191460 – Stage III – 236 intake, 243 exhaust .492 intake and .453 exhaust lift and 128 degree lobe separation

Ti-VCT And COMP’s Phaser Locks and Limiters

The Twin Independent Variable Cam Timing in the 5.0L Coyote engine allows the vehicle’s PCM to advance and retard intake and exhaust cam timing independently of one another, delivering improved fuel economy, power, and reduced emissions. By way of an internal hydraulic oiling system controlled by the PCM and operating on oil pressure, the camshaft gears can advance or retard both the intake and exhaust by as much as 50 degrees, depending on the driving situations.

COMP Cams' new phaser limiters install within the valley between the inner and outer phaser of the cam gear drive, limiting the Ti-VCT cam timing to 20 degrees of maximum advance or retard.

“With the shorter duration of the lower-lift factory camshafts, there’s a requirement from the OE perspective to have a wide range of camshaft sweep – normally 50-60 degrees,” explains Patrick. “At part-throttle cruising, they can retard the camshafts back significantly and that essentially throttles the engine without using the throttle blades, which creates some impressive fuel economy gains by reducing the pumping losses in the engines.” The larger XFI NSR camshaft adds duration, meaning the valves are open for a longer period of time. Thus, the maximum amount of timing must be limited or in some cases, even locked down to avoid piston-to-valve clearance issues.

The phaser limiters, which install within each of the four cam phasers, limit the cam timing window, thus reducing the chances of piston-to-valve clearance issues due to the higher lift of the new camshafts.

Continued Patrick, “The reality is that at wide open throttle, you really only need about 13-15 degrees of cam retard in peak RPM situations, and from a horsepower standpoint, we really don’t need anything more than 20 degrees of phaser movement.”

This is where COMP’s phaser limiters, which are placed within the camshaft phaser gears and physically limit their movement, come into play. And according to Patrick, by mechanically limiting the phasers to 20 degrees rather than 50 or 60, a much larger piston-to-valve clearance area is opened up to their engineers to get more aggressive ramp profiles, higher lift, and longer durations without fear of interference issues.

The question you may be wondering however – and you aren’t alone – is why a phaser limiter is necessary if the cam timing is ultimately controlled by the PCM? “The problem is that nothing is perfect, and it takes a few milliseconds for all of this to start working and moving. You can imagine during a drag race race launch at 7,000 RPM, when you dump the clutch, you have instantaneous drops in RPM. The computer may want to command a certain cam position, but unfortunately it may take a few split seconds for the phaser to actually move to that position. And it may only take those few engine rotations with the piston and valve occupying the same place to bend parts.” explains Patrick.

After physically limiting the maximum cam timing through the use of the phaser limiters, one must then plug those new values into the PCM, as Brenspeed has done here through the SCT Advantage III software. Outside of flash tuners like DiabloSport and SCT, full stand-alones like FAST's XFI can also electronically limit the cam timing.

Because the computer controls the position of the phaser and ultimately the cam timing, degreeing the cam isn’t necessary with the phaser limiters. If however, one were using the phaser lock for a drag racing-style setup, Patrick insists that you’d certainly want to degree the cams. “If you’re going to run the locked phasers, you really need to degree them and make sure they’re installed where you want them setup for your engine combination. Particularly on the 4-valve engines, there’s so much timing chain and other elements that the potential tolerance range of where the cams will actually install in the engine is much wider than a traditional V8 with a single cam in the center of the engine.”

Install And Dyno Testing With Brenspeed

Now that we’ve taken a closer look at the camshafts, it’s time to see what they’re made of as we hook up with Brent White and the crew at Brenspeed at their immaculate new facility in Northern Indiana for some laps on the dyno to see what kind of power gains we can achieve.

Our installation process begins by removing the intake and fuel rails, the radiator fan, and the engine's front cover so that we can gain access to all of the valvetrain components. From there, the entire tensioner and timing chain assembly is removed as one, allowing us to then remove the factory cams.

Before we can install our XFI NSR Stage 2 camshafts, we first have to remove the factory cams and gear drive assembly, and naturally, this begins with removal of the front cover. From there, the timing chains are removed and the camshafts will slide out as an assembly (cams, gear, and phaser) on each side. The phasers, timing chain, and both tensioners all slide off as a single component and can be reinstalled in the very same manner.

With the phaser removed from the camshafts, the front cap must be removed in order to install the phaser limiters. Within the phasers is a large vane on each side with a pin inside that locks into position when the vehicle is turned off. With the pin locked, the COMP Cams phaser limiters slide in and remain in place.

In order to install the phaser limiters or phaser locks, the front caps on each phaser have to removed once they're out of the engine.

The most critical element of the installation process is ensuring the timing marks are aligned on the phaser when sliding the new cams back into place. Once the camshafts are in, the entire phaser, timing chain, and tensioner assembly will slide back into place as one onto the cams. You can then bolt everything in place and reinstall the timing chain.

Finally, because you’re now limiting the cam timing to only 20 +/- degrees maximum, those parameters must also be programmed into the computer, keeping it from insisting upon a value of advance or retard that it can’t physically achieve. With his step complete, we’re ready to hit the dyno.

When installing the new camshafts, you want to make certain the notches in the phaser and gear are aligned. Thanks to the computer-controlled Ti-VCT, degreeing of the camshafts is a thing of the past. If however, you opt for the phaser locks, you'll need to break the degree wheel out and lock them down to your desired timing.

Brenspeed has been working closely with COMP Cams of late to hone in on the the sweet spot for various driving conditions and applications, and as such, White and company have “well over 100 dyno runs” on their 2011 GT with the XFI NSR cams.

Explains White, “When we’re trying to dial these cams in, we’ll made a lot of runs; maybe adjusting off the intake cam angles, trying to see where each angle makes the best power. Then we’ll do the same thing on the exhaust side, and once we go through all of the data, we’ll try to put all of those angles together in a certain RPM range. Because what you do at 7,000 isn’t what you’ll do at 1,000. Once we have ample amounts of data, we can wrap it all up with an ideal set of angles to produce the best low end torque but also the best peak horsepower.”

In order to put the COMP Cams Stage II XFI NSR camshafts to the test, we hooked up with Brent White and crew at the impressive Brenspeed facility in Indiana, where we flogged their 2011 Mustang GT test bed on both the dyno and the street.

On their Mustang testbed using a fully calibrated and dialed-in combination, Brenspeed found horsepower and torque gains of 28.2 horsepower and 21 ft-lbs at 7,000 RPM with the Stage II cams. Modifications to the car include headers and a catted H-pipe from Kooks, Magnaflow exhaust, and a JLT cold air intake. Prior to the cam installation, our Mustang test bed registered a maximum of 417 horsepower at 6,500 RPM and 388 ft-lbs at 4,400, with results of 438 peak horsepower at 6,700 and 387 ft-lbs at 5,400 with the new cams. As summarized by White, “The cams start picking up right around 5,000 RPM, and because these engines shift at about 7,300 I believe your RPM will fall back into the power band of the cams after each shift.”

Numbers Recapped

• Before – 421 hp, 388 ft-lbs
• After – 440 hp, 388 ft-lbs
• Peak Gain – 19 hp 0 ft-lbs
• Gain near red line – 28 hp 21 ft-lbs

Our dyno tests at Brenspeed revealed increased of nearly 30 horsepower and just over 20ft-lbs of torque with the addition of the Stage II XFI NSR camshafts, conmbined with some minor bolt-on modifications.

After two full days at Brenspeed learning more about the COMP Cams XFI NSR line of cams and beating up on the cammed-up 2011 Mustang GT, we must say that we’re mightily impressed with these new pieces, as much of the Mustang enthusiast market has already learned. Thanks to the design and implementation of this lineup as a drop-in aftermarket replacement, one can beef up their 2011-2012 GT with what for many is a DIY install, reaping the benefits of locked away horsepower and torque and the industry-renowned quality of COMP Cams at a cost that won’t break the bank.