2003 Ford Mustang Cobra Xtreme Team Four Valve Cams - Mods For Mods Part 3

Just in case you haven't been following our Mods for 4-V Mods series, we started out by installing the Ford Racing '03 Cobra crate motor on the engine dyno and tuning, exhausting, and boosting our way to over 500 hp.

Combining 23 degrees of total timing and an air/fuel ratio of 11.8:1, the supercharged four-valve belted out 488 hp and 455 lb-ft of torque. Adding a throttle body and long-tube headers upped the power peak to 508. It was here we installed blower and crank pulleys. The additional boost pressure (from 8.7 psi to over 14 psi) eventually netted us 539 hp and 569 lb-ft of torque.

Part 2 of our series saw us replacing the Eaton supercharger with an intake manifold from a normally aspirated '01 Cobra in an effort to demonstrate the power added by the supercharger. We then installed a Kenne Bell twin-screw blower that upped our power peak to 682 hp and eventually over 700 with increased boost pressure. We finished off Part 2 by testing a Bassani cat-back exhaust.

With our Mod for 4-V Mods series now in full swing, we decided it was time for our '03 Cobra mill to join Team Xtreme. In our case, Team Xtreme meant the installation of a set of new four-valve cams available from Comp Cams. Like its selections for the two-valve Modulars, Comp offers a wide variety of different cam profiles to meet the needs of four-valve Cobra enthusiasts.

Naturally, not all four-valve 4.6s will respond to the same cam profile, so Comp whipped up no less than 10 combinations ranging from mild replacement cams to maximum effort race cams. It even offers cam combos for supercharged and nitrous applications. The new Comp four-valve Modular motor cam choices are broken down into three series, the Xtreme RPM, the Xtreme XE-R, and the XE-R Supercharged and Nitrous grinds. All of the Xtreme RPM cams featured .425 lift, with duration figures ranging from 218 degrees (at .050) to 234 degrees. The remainder of the Comp offerings featured a split lift of .475 intake and .450 exhaust. The Xtreme XE-R series shared 114-degree lobe separation angle, while the supercharged and nitrous cams all featured slightly wider 116-degree lobe separation angles.

When choosing a grind for our supercharged '03 motor, our first choice would be running something under the heading XE-R Supercharged and Nitrous cams. Unfortunately, these required a valve spring upgrade (PN 26123) which was not available to meet our dyno schedule. Rather than give up and reschedule the test for next month, we decided to do the next best thing and proceed forward with the cam test by choosing four-valve cams that did not require a spring upgrade. Basically, this meant something from the Xtreme RPM category that featured only .425 lift.

The low lift figures allowed us to retain the stock Ford valve springs without fear of coil bind. After looking over the four Xtreme RPM offerings, we chose the XE262AH-14 cams (PN 106100). According to the supplied literature (and catalog), the XE262AH cams were designed to provide great street performance with significant horsepower and torque gains without computer modifications. Basically, the XE262AH cams seemed to be a perfect performance plug-and-play proposition. For our F.A.S.T. engine management, the plug-and-play feature wasn't as important, but it sure would be for the vast majority of Cobra owners. The dual-pattern XE262AH cams offered 226 degrees of intake duration, 222 degrees of exhaust duration, and a 114-degree lobe separation angle to go along with the .425 lift (both intake and exhaust).

Those eagle-eyed readers who have checked out the spec box may have noticed that the supercharged cams were dual-pattern as well, but the difference between the Xtreme RPM and XE-R Supercharged cams was that the supercharged versions featured more exhaust duration. Our XE262AH cams offered four degrees more intake duration (226 degrees vs. 222 degrees), but the comparable supercharged cam featured a 2-degree split (224 degrees vs. 222 degrees) skewed in favor of the exhaust. In a future issue we will be experimenting with these different cam profiles by running a back-to-back test, but for now, we just concentrated on getting the XE262AH NA cams installed properly. A huge thanks goes out to Accufab's John Mihovitz for providing the necessary tools for performing the cam surgery on our four-valve engine.

While the main components are very similar to the two-valve GT engine, the four-valve also featured a secondary drive assembly from the exhaust cam to the intake. This secondary chain drive naturally required a second pair of cam sprockets and a dedicated chain tensioner. The cam swap also required removal and compression of all 32 of the hydraulic lifters. In the end, it was not terribly difficult, just time-consuming.