Words And Photos: Richard Holdener

For some reason, Mustang enthusiasts tend to avoid cam swaps on Ford Modular motors. They seem to think that the overhead cam design is too complex to work on, but that couldn’t be farther from the truth. This is especially true of the two-valve (2V) variety. Anyone who has ever successfully performed a cam swap on a conventional Ford (big or small block) can easily perform the same operation on the Mod motor. All you have to do is line up the marks on the chain and timing gears-just like any Ford. Given this revelation, the question becomes less of whether you can and more of whether you should. After all, replacing the cam(s) on any motor is considerably more difficult than say your average throttle body upgrade, so the question now becomes, is it worth all the trouble? If the power gains on this supercharged two-valve are any indication, the answer is a resounding yes!

Having tested multiple cam upgrades on normally aspirated 4.6L Mod motors, we decided to add a little spice to this test by swapping cams on a supercharged two-valve motor. To keep things interesting, the 4.6L 2V motor remained mostly stock. By mostly, we mean all the critical elements, including displacement, compression and head flow. The 4.6L 2V test mule was supplied by Sean Hyland and featured forged internals including an 8-bolt, Cobra crank, forged rods and forged JE pistons. The forged slugs were designed to reproduce the factory 9.3:1 compression ratio when combined with the stock PI combustion chambers. The major alteration to the otherwise stock mod motor was a supercharger upgrade from Ford Racing. Wanting to demonstrate the effect of the cam swap under boost, we chose to top the test motor with a power producer right out of the Ford Racing catalog. The non-intercooled system was designed for low-boost, street applications, which made it perfect for our mild cam test.

To prepare for the dyno test, the 4.6L was configured with a set of Kooks 1 5/8-inch, long-tube headers, a crank case full of Lucas 5W-30 oil and FAST 36-pound injectors. Since tuning was critical on this supercharged cam test, we relied on a FAST XFI management system to dial in the air/fuel and ignition timing. The blower was equipped with a 3.4-inch blower pulley that produced a maximum boost pressure of 9.1 psi at our self-imposed rpm limit of 6,200 rpm, though it can be noted that peak power came at just 5,900-6,000 rpm. Run with the stock 1999-up, Power-Improved (PI) cams, the supercharged 4.6L produced 407 hp at 5,900 rpm and 417 lb-ft of torque at 4,000 rpm. This represented a significant jump from the 298 hp produced normally aspirated. Thanks to the combination of long(ish) intake runners and immediate boost, torque production exceeded 400 lb-ft from 3,100 rpm to 5,000 rpm. The boost curve offered by the Ford Racing blower started at 5.4 psi at 2,500 rpm and rose to a peak of 9.1 psi at 6,200 rpm. Though the power had peaked at 5,900 rpm, boost continued to climb with engine speed, a sure indication of the presence of a restriction.

After confirming the baseline power numbers with the stock cams, off came the damper, front cover and valve covers to prepare for the cam swap. Obviously cam swaps are much easier on the engine dyno, but Mustang enthusiasts seem less afraid of the time spent unbolting the covers than properly lining up the cams. Removing the spark plugs allowed us to rotate the motor to position number 1 cylinder at TDC. After doing so, we removed the rockers and cam tensioners to allow for removal of the timing chains. Before removal of the rockers, we hit the cam sprocket bolts with an impact gun to facilitate swapping them over to the new cams. Our stock cams were positively located by key ways in the sprockets, but some modular cam/sprocket combinations were not so equipped. You have a couple of options here, you can replace the non-keyed factory sprockets with factory keyed versions or replace them with adjustable sprockets from COMP Cams. It is also possible to simply line up the key way in the new cams with the slot in the non-keyed factory sprocket and tighten the hell out of the cam retaining bolt, but know that it is difficult to tighten the bolt without altering the relationship between the sprocket and cam.

With daily street driving in mind, we chose the mildest of the available shelf cams from the COMP Cams catalog. Designed for the later PI heads, the XE262AH cams offered .550 lift, a 226/230 duration split and 113 lsa. The cams were installed and bolted in place using the factory cam towers. After the cams were in place, we lined up the chains and sprockets and installed the chain tensioners. The cam and crank sprockets (still at TDC) had marks as did the timing chains. All we had to do was line up the marks on each and it was done. Before installing the rockers, we compressed each lifter in a vice to drain the oil and relieve the pressure. This allowed us to compress the lifters during rocker installation. After the last rocker was in place, on went the covers (don’t forget the crank trigger) and damper. Equipped with the new COMP Cams, the boosted 4.6L produced 436 hp and 428 lb-ft of torque. With the new cams, power increased from 3,300 rpm to 6,200 rpm, with significant gains above 5,000 rpm. As icing on the cake, the cam swap also dropped boost pressure by 2 psi, from 9.1 psi to 7.1 psi, making these COMP Cams a Mega modification for your 4.6L Ford.

The graph tells the story, as swapping out the wimpy stock PI cams for even the mildest grinds from the COMP Cams catalog resulted in some serious power gains. The 4.6L test motor was essentially a stock PI motor that had been augmented with forged internals from Sean Hyland Motorsports. Despite the extra strength of the reciprocating assembly, the displacement, compression and cylinder heads all remained stock. The only upgrade was the addition of the Ford Racing supercharger system. Run with a 3.4-inch blower pulley, the supercharged 2V motor produced 407 hp at 5,900 rpm and 417 lb-ft of torque at 4,000 rpm. After installation of the COMP XE262AH cams, the peak numbers jumped to 436 hp at 6,000 rpm and 428 lb-ft at 4,100 rpm.

The extra 30 hp was obviously a welcome increase, but check out the effect the cam swap had on the boost curve. Since the Ford Racing supercharger lacked any type of intercooling (a perfect application for a Snow Boost-Cooler kit), keeping boost down was a major priority to help suppress detonation (boost and charge temp go hand in hand). The cam swap not only netted the additional 30 hp but also dropped peak boost pressure by 2 psi (from 9.1 psi to 7.1 psi).

Sources

COMP Cams
compcams.com

FAST
fuelairspark.com

Ford Racing
fordracingparts.com

Lucas Oil
lucasoil.com

Sean Hyland Motorsports
seanhylandmotorsports.com