How much are cams worth on a supercharged version of the 4.6L Ford?

Words and Photos: Richard Holdener

Before beginning the build up of any motor, you have to ask the all-important question. Is this motor really a player? Case in point, the 4.6L two-valve Modular Ford. There were tons of them made, certainly more than the more exotic four-valve Cobra stuff, but the 2V guys get little, if any, respect. Taken in perspective, the two-valve replaced the original 5.0L Ford, literally a legend. Down on displacement, power, and the rpm potential promised by the overhead cam design, the Modular Ford fought an uphill battle. As if two-valve owners didn’t have enough to worry about back in the day, things are even worse now. Forget about the 300-hp three- and four-valve mod motors; Ford went and introduced the 5.0L Coyote, upping the power ante by more than 100 hp. Naturally, Chevy and Dodge followed suit, and now the original two-valve is surrounded by 400-, 500- and even 600-hp giants. Once again, this begs the question: How do 1996-2004 SOHC two-valve Mustang owners compete? The answer (as always) is boost!

To illustrate just how well a boosted two-valve can be, we set up a test using a Vortech supercharger. While boost can be used to help solve your power woes, there is boost, and then there is BOOST (that’s right, all caps)! You see, fellow Ford fanatics, adding boost to just any combination will not result in the desired power output. Sure, boost applied to even a stock motor will increase the performance, but apply that same boost to a modified motor and you have the makings of some serious power. That is where things like cam timing come into play. How much can the right cam be worth on a supercharged mod motor, you ask? The answer might surprise you, as this test indicated some profuse power gains on an already healthy motor.

Working with cylinder head flow and the intake manifold, cam timing is one of the big three components that determine not just the peak power, but the overall shape of the curve. Match the components and you have a winning combination. Miss on just one of them and watch the power needle plummet.

Looking to find out how beneficial cam timing is on a supercharged application, we obviously needed three things: a test motor, some cams, and some boost. The test motor was easy enough, as we had a 4.6L two-valve test mule on hand already built and ready to rock and roll. The PI motor was build for boost, with a short-block that consisted of a forged Cobra crank, Speedmaster rods, and Ross Racing pistons. Also present was a set of Total Seal rings, while the short-block was topped with a set of ported PI heads from Total Engine Airflow. The finishing touches on the mod motor included ARP head studs and Fel Pro MLS head gaskets, along with a PI intake and Accufab 75mm throttle body.

The two-valve was first run on the engine dyno with a FAST XFI management system, 36-lb. injectors and Hooker long-tube headers. Run with the stock PI cams in normally aspirated trim, the two-valve produced 361 hp and 358 lb-ft of torque, but we were most interested in what the thing made under boost.

After running the motor in normally aspirated trim to ensure we had a healthy candidate for the cam test, it was time to add boost. For this test, boost came from a Vortech supercharger kit designed for the two-valve Mustang application. We did take the liberty of upgrading the supercharger to the more powerful T-trim (for future use), but even the V2 or V3 Si superchargers were more than adequate at the power levels run on this test. In addition to the T-trim, the Vortech Tuner system included an air-to-water intercooler and all the necessary hoses, clamps, and fittings to mount the components. Because the Vortech kit was designed to utilize the accessories, we had to improvise a drive system on the dyno, but managed to create a system that provided a repeatable boost curve with no belt slippage. The blower kit was configured with a 3.33-inch blower pulley that (when combined with the stock crank pulley) produced a peak boost pressure of 12.6 psi. Run with the stock PI cams, the supercharged 4.6L produced 551 hp and 505 lb-ft of torque. Now, it was time to perform our cam swap.

With the motor still warm from the previous runs, off came the damper, front cover, and valve covers. Out came the stock cams and in went a set of COMP XE274H sticks. For this test, we ran a pair of non-PI cams that offered .500 lift (intake and exhaust), a 236/240-degree duration split, and 114-degree lsa. Plenty powerful even for a normally aspirated combination, we were anxious to see how well they performed on our blower motor. We made sure to degree the cams after installation, to ensure the cam timing was identical side to side. Installation of the cams was made easier by bleeding the lifters down in a vice (the rockers snapped in place after installing the cams).

Vortech 4.6 Cam Test-Stock vs Comp XE274H
As is evident by the graphs, replacing the stock cams with the COMP XE274H units offered substantial power gains on this supercharged application. No slouch even with the stock cams, the supercharged 4.6L produced 551 hp and 505 lb-ft of torque. After installation of the COMP cams, the power jumped to 655 hp and 556 lb-ft of torque. An LS owner usually has little to fear from a 2V Mustang, unless they happen to be sporting over 650 hp from a combination like this.

After dialing in the air fuel and timing curves once again, we were rewarded with a substantial improvement in power. The peak numbers jumped from 551 hp and 505 lb-ft to 655 hp and 556 lb-ft of torque. The cam swap was worth more than 100 hp on this supercharged two-valve motor. Though it might be slightly more involved than a traditional V8, the results of adding a pair of boosted bump sticks were well worth the effort!

Sources: ARP, Arp-bolts.com; COMP Cams, compcams.com; FAST, fuelairspark.com; Holley/Hooker/NOS, holley.com; Speedmaster, Speedmaster79.com; Vortech Superchargers, vortechsuperchargers.com