If you saw "Ring My Bell" elsewhere in this issue in which we installed these same cams in an '03 Cobra 4.6 (run in normally aspirated trim with an '01 intake), the cams were installed using the factory sprockets and wound up at 117 degrees on the intake and 113/115 on the exhaust. Relative to the cams installed for this test, the '03 Cobra cams were retarded by 7 degrees on the intake and 1-3 degrees on the exhaust. On the later Cobra 4.6, the cams improved the peak power considerably, but actually lost power below 4,500 rpm.
Advancing the cams (per Mihovetz) on this early application resulted in the same impressive peak-to-peak power gains, but the most welcome part of the equation was that the XE262AH cams offered power gains from 3,000 rpm all the way to 6,500 rpm. The largest power gain came at 6,600 rpm where the Comp cams upped the power output by 42 hp. From 5,000 rpm to 6,600 rpm, the cams really came alive, but they offered improved power all the way down to 3,000 rpm. This improved low-speed power ensures driveability and adds some much-needed torque production.
While the cams offered a sizable jump in peak power and even upped the low-speed and midrange torque, we are still a long way from the potential of the 4.6.
As we continue our search for additional power from this '96 Cobra 4.6, we will have another intake manifold to test along with our first shot at forced induction. Kenne Bell has promised us a chance at one of its non-intercooled blower kits for this early Four-Valve mill, and we have a twin-turbo kit waiting in the wings. Of course, we will have to run a centrifugal supercharger, as well.
Before getting to the blower and turbos, we may retard the existing cam profiles in an effort to demonstrate what happens when the cams are installed incorrectly. We wish we had that data for you this month, but degreeing and adjusting the cams on this combination all but ate up the available dyno time. We will probably take the opportunity to change the valvesprings, since the 100,000-mile engine is probably in need of a new set of springs anyway. A huge thanks goes to Mihovetz for performing the cam work on this baby.
The cams were coated with...
The cams were coated with assembly lube to provide lubrication during startup.
The dial indicator was also...
The dial indicator was also used to check piston-to-valve clearance since advancing the intake cams will decrease the clearance.
This tool was used to compress...
This tool was used to compress the valve spring to facilitate removal and installation of the rocker arms.
After setting the new Comp...
After setting the new Comp cams at 110 degrees (intake) and 112 degrees (exhaust), the Four-Valve Cobra 4.6 pumped out 373 hp and 347 lb-ft of torque. Advancing the cams allowed the new Comp profiles to improve not only the peak power but also the power from 3,000 rpm all the way to 6,600 rpm.
The power curves illustrate that not only did the mild XE262AH cams provide impressive peak power gains, upping the output from 339 hp to 373 hp, but there were also impressive midrange power gains. The reason we improved the low-speed power so much on this test is that we went to the trouble of degreeing and adjusting the cams during the install. Mihovetz advanced the cams to 110 degrees on this early 4.6. Advancing the cams paid big dividends below the torque peak without sacrificing much, if any, power on top. The Comp cams improved the peak power from 339 hp and 332 lb-ft of torque to 373 hp and 347 lb-ft of torque. Better yet, the cams improved the power from 3,000 rpm to 6,500 rpm.