Richard Holdener
July 1, 2006

IN PART 1 of our "Remember The Titans" series last month, we took a look at a few bolt-on performance components for the early ('96-'98) Cobra 4.6. As you know, the early DOHC mod motor differs from the late-model version by way of cylinder heads and intake manifold. The early versions featured dual-port heads and a matching intake, while the late-model Four-Valves were equipped with a single-port head.

The bolt-on performance parts applied to the high-mileage '96 Cobra 4.6 included a set of IMRC eliminator plates, a revised intake manifold, and a shot of nitrous. The test engine was already equipped with a set of headers, an Accufab throttle body, and a FAST engine management system. The motor was run sans accessories and with an electric water pump. Equipped as such, the 4.6 produced 339 hp at 6,100 rpm and 332 lb-ft of torque at 5,000 rpm.

Early 4.6 Cobra engines were not known for torque production, but the curve nevertheless managed to exceed 300 lb-ft from 3,500 rpm to 5,900 rpm. Certainly not huge power by any means, but these Cobra 281s more than held their own back in 1996, and with a little help, can be made to produce impressive power even a decade later.

With our nearly stock 4.6 ready for more improvements, we decided to step up to a set of cams next. Our cam choice was made with streetability in mind rather than maximum peak power. Were we looking to maximize power production in the top third of the rev range (where it is most useful on a dragstrip), our cam choice may well have been different, but we wanted to improve the power without sacrificing driveability and/or low-speed response.

Given the lack of torque production from the oversized intake ports (in both the head and manifold), the last thing we wanted was to further reduce torque production with excessive cam timing. We wanted a set of cam profiles that we would feel comfortable driving every day. That said, we were also hoping for some healthy power gains. Was the combination of additional power and streetability too much to ask for?

We hoped not, with proper cam selection and (every bit as important) proper cam timing. When it comes to 4.6 Four-Valve cams, dialing in the cam timing can make or break the power curve. Excessive advance or retard can literally throw away half of the power gains offered by the more aggressive cam profiles. Naturally, the installation and degreeing of four cams in the DOHC motor are a bit more involved than swapping the bumpstick in your typical pushrod 5.0, but the results are well worth the effort.

First up was the cam selection. In choosing a set of cam profiles (one set of intakes and one exhaust), we purposely went conservative. Rather than skip right to the bottom of the page in the catalog where all the wild grinds reside, we chose a set that not only promised impressive driveability, but also allowed us to install the cams without resorting to a valvespring change. Though such a change should be considered mandatory when changing cams on a motor with 100,000 miles, we decided to illustrate the potential power gains without the benefit of the spring upgrade. We knew the motor was not going to run (effectively) beyond 6,500 rpm (for our testing), so we felt confident performing the cam swap without the springs.

We will revisit the valvespring issue later in the series, and may even readjust the cams from their present position to illustrate the change in the power curve. For this round of testing, we chose a set of XE262AH cams from Comp Cams. The XE262AH (PN 106100) profiles combined 0.425 lift on both the intake and exhaust with a dual-pattern duration split of 226/222 degrees. The wide lobe separation of 114 degrees helped ensure both idle quality and driveability. According to the Comp catalog, the low lift and duration values did not require a valvespring upgrade (PN 26123).