Camshaft Shootout: Best Cams for the 4.6/5.4 Ford V8

One of the most misunderstood performance components on any motor has to be the camshaft or camshafts. The difficulty is only compounded when you add things like forced induction to the mix. From an anatomical standpoint, camshafts can be likened to the brain, as the cam profile determines how effectively (when and where) breathing takes place. Camshafts are one of the major determining components of the effective operating range of the motor. Of course, the cam timing must be combined with the proper intake manifold, head flow, and primary header tube length for optimum operation over a given RPM range. Stock or ultra-mild aftermarket cams will provide a dead smooth idle, while more radical grinds can transform that mild-mannered motor into one radical ride. The radical route usually includes ill-tempered, cantankerous behavior until the motor comes on the cam, but such is the price for all that high-RPM heaven.

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Many mod-motor enthusiasts at least understand the basics of cam timing. They realize that so-called “Saturday-Night Special” grinds are much wilder and potentially more powerful than the production cam profiles. The problem arises when deciding to choose between these two extremes, especially for a daily driver. The temptation is certainly to go big on the cam profile; after all, isn’t bigger always better? The problem with going big is twofold. The first problem is that the cam profile must be selected not just for bragging rights at the drive-in (or coffee house), but rather to work with your existing components. Adding the right cams to your otherwise stock motor can result in impressive power gains. Adding wild cams to your otherwise stock motor will likely hurt your power throughout the rev range and can even decrease peak power since the cams were designed to run effectively at 8,000 rpm and the rest of your stock components (intake runner length, head, and exhaust flow) sign off at 6,500 rpm. As a general rule, the closer to stock the rest of your engine is, the milder the cam profiles should be. This means leave those weekend warrior cams to the drag racers and stick with mild but effective profiles that will offer power gains not just at high RPM, but also throughout the rev range. After all, what good is it to add 25 hp at the power peak only to lose 35 ft-lbs down at 3,000 rpm? Think for a moment about where (what RPM) you spend most of your time driving and choose a cam accordingly!

 

 

 

 

While naturally aspirated cam choices are difficult enough, just look at any book on the subject of forced induction and skip to the section on camshafts. The recommendation will probably be to run stock cams, or at least to stay away from the dreaded duration or overlap that can cause all that precious boost to escape out past the exhaust valve. While blowers (and turbos) work fine on stock motors equipped with stock cam profiles, like their naturally aspirated counterparts, they respond very well to more aggressive cam timing. In fact, for most street applications, the camshaft chosen for a mild naturally aspirated motor will work equally well with a supercharger. Sure, you can tailor the specific cam timing for supercharged use, but the gains (compared to a naturally aspirated performance cam) will be minimal at most mild boost and power levels run on the street. This is actually good news for enthusiasts, as choosing the right cams for a blower motor is actually as easy as selecting them for a naturally aspirated motor – in many cases you can go with the very same cams. The manufacturers list applications for their cams and many have included profiles for forced induction motors, but the NA cams work well too. How do I know that NA cams work well on forced induction applications? Just check out the results of Tests 5 and 8.
Many mod-motor owners have steered clear of cam swaps, fearing the overhead cam configuration. Know that swapping cams in a 4.6L 2-valve or 4-valve motor is a bit more involved than performing the same task on a 5.0L V-8, but like anything else, once you’ve done it once or twice, you’ll wonder why you avoided all that extra power for so long. As is usually the case, stock cam profiles leave something to be desired in terms of maximizing power. It is possible to add performance cams to your 4.6L (2-valve or 4-valve) and gain power across the rev range, though the wilder (more powerful) profiles will usually cost some low-speed power in trade for the significant gains in midrange and top end. modular motors respond well to aggressive cam timing, though the 2-valve motors are ultimately head flow limited, so ultra-wild cam profiles will be less beneficial than on the free-flowing 4-valve motors. This chapter illustrates the gains offered on naturally aspirated and supercharged 2-valve and 4-valve combinations, but know that similar power gains are available on turbocharged mod motors as well. Don’t fear the cam swap on a mod motor, just take things slow and have the factory manual handy as a reference. In a day or so your motor will be up and running with a nasty new attitude.

The one thing missing in the modular world (a deficiency cured by the author after this testing) was the availability of adjustable cam sprockets. While cam swaps certainly offer power gains, they can be maximized only after degreeing the cams. In the case of modular motors, the cams on the right bank of cylinders are not always in alignment with the cams on the left bank. On 4-valve motors, we’ve measured differences in intake cam timing of 9 degrees (one cam was 9 degrees retarded relative to the other). Naturally, one setting is going to produce more power than the other, but the real concern is that the two banks of cylinders produce different relative power outputs. This unbalanced power production is not desirable, but the only way to cure it is to degree and adjust (synchronize) the cam timing side to side. Power production can be further enhanced by advancing or retarding the cams (in unison), to find optimum power. Additional gains will likely come at the expense of power elsewhere, as advancing the cams (especially the intake) will likely improve low-speed power while retarding them will have the opposite effect. This will change somewhat after adding a blower or turbo, but it will be nice to be able to optimize the power output with adjustable cam sprockets.

 

Test 1: Early 2-Valve GT: Comp Cams XE274H Camshafts

After spending some time tuning the base fuel and timing tables, we eventually coaxed this non-PI 4.6L engine to 260 hp and 341 ft-lbs of torque. We managed to match the flywheel rating of the new, more powerful PI GT motors, but before you get all in an uproar about happy dynos and exaggerated power numbers, remember that this reading was taken with long-tube headers, no MAF or air inlet system other than a 3-inch tube and cone filter, and no accessories. The idea was not to exceed the 260 hp offered by the late-model GT motor, but rather to establish a baseline to improve upon.

After I was confident about the repeatability of the baseline power numbers, I decided to start swapping some hard parts. First on the list for the early 4.6L was a set of performance cams. Wanting more than 5 to 10 extra horsepower, I decided to go big in terms of cam profiles and selected the largest Xtreme Energy grinds available for the early 4.6L GT motor. The dual-pattern XE274H cams offered a 236/240-degrees duration split, along with .500 inches of lift for both the intake and exhaust. A wide 114-degree lobe separation angle helped tame the cam somewhat, but the duration ensured that these cams lived up to the description of “Hot Street Cams” given in the Comp Cams catalog. Comp Cams also recommended steeper rear-end gears, a higher stall speed (if automatic equipped), and computer upgrades (otherwise known as getting a chip or tune). Our F.A.S.T. programmable ECU obviously fell under the last category, so we felt confident that we could provide any fuel or timing changes that were needed. The new cam profiles required a valvespring upgrade, so Comp Cams supplied a set of 26113-16 springs to provide sufficient seat and open pressure (along with the necessary coil-bind clearance) to ensure proper valve control.

Though designed to operate effectively from 2,000 rpm to 6,000 rpm, we found out in testing that the stock non-PI GT intake manifold kept peak power well below 6,000 rpm. Still, I had high hopes for the cam upgrade. After installing the springs and XE274H cams, the peak power jumped from 260 to 301 hp. The early GT was now making at least as much as (and possibly more than) a later PI GT motor. The peak torque was up as well, by 5 ft-lbs. Not surprisingly, the motor lost a bit of power below 3,400 rpm, but beyond that it was all power. With an effective power band of 3,500 to 5,500 rpm, these cams would do nothing but improve acceleration. With as much as 50 extra horsepower available thanks to the cam swap, the extra acceleration would be significant. In fact, I’d have to say that the wimpy stock intake and heads were now holding back this early GT motor from making serious power.

 

 

 

 

Test 2: PI 2-Valve GT: Six Sets of Comp Cams Xtreme Energy Camshafts

If you learn anything from this chapter on performance camshafts it should be that wilder cam timing does indeed improve power. In reality, the question isn’t so much whether performance cams will add power, but more of which cam is the right one for your application. The intended application should dictate the cam choice, but the chosen cam may also reflect your personality. Do you have the crust trimmed from your bread while you’re watching the cooking channel? Then a stock cam with its (pre-prison) Martha Stewart smooth idle is probably for you. If, on the other hand, your tastes tend more toward Tater Tots and beer while fast-forwarding to the Seth Enslo jump on Crusty Demons of Dirt, then drop right to the bottom of the cam page where the big ones are. Like you, the idle is a little rough around the edges, but things start to kick ass when you come up on the cam. Crusty Demons notwithstanding, the intended use is actually the most important factor when choosing a cam. Obviously, the cams chosen for a drag-race motor would differ from those optimized for street use or even a road-race application.

Also consider the existing engine combination, as the cam profile must work in conjunction with the intake manifold, cylinder heads, and exhaust system to produce maximum power in a given RPM range. It makes no sense to install cams designed to make peak power at 7,500 rpm when the rest of the components sign off at 6,000 rpm. In all likelihood, most people won’t be building dedicated (single-purpose) motors and will instead have existing stock or mildly modified motors that they deem in need of performance cams. Given that the vast majority of modular motors are of the 4.6L 2-valve variety, this test was designed to help you select the proper cam for your combination. It’s impossible to run every cam in every conceivable combination, but I was able to test every one of the six different Comp Xtreme Energy (both PI and non-PI) sets of cams against the stock cams in a modified 4.6L 2-valve motor.
Though all of the Comp Xtreme Energy cams offered power gains over stock, they did so differently, and in every case, the power gains were accompanied by losses in power somewhere in the rev range (usually down low). The milder cam profiles (like the 262H and 262AH) traded very little torque down low (15 to 18 ft-lbs) for the power gains achieved above 4,500 rpm (48 to 58 hp). The larger profiles (like the 278AH) dropped 35 ft-lbs down low, but offered as much as 77 hp at 6,500 rpm. As indicated earlier, the choice is ultimately up to the vehicle owner. Just be sure that you are honest about the intended use, and don’t be tricked by the big power numbers out at 6,500 rpm. Your street motor will spend a lot more time driving around from 2,500 rpm to 4,500 rpm than at wide open throttle at 6,500 rpm. Also realize that this DSS-built test motor featured CNC-ported heads from TEA, a PI intake with Accufab 75-mm throttle body and inlet elbow, and a set of Hooker headers. The power probably wouldn’t be as great on a milder combination. Be sure to check out all of the following graphs, as this test involved six different sets of Comp cams, as well as the stock PI cams.

 

 

 

 

 

 

 

 

Test 3: Ford Racing Supercharged PI 2-Valve GT: Comp Cams XE262H Camshafts

The Sean Hyland Motorsport (SHM) 4.6L test motor was one of the more desirable (1999-’04) Power-Improved (PI) engines. It featured a forged reciprocating assembly (stock compression) topped off with bone-stock PI heads, cams, and composite intake manifold. The SHM motor was topped off with a Ford Racing supercharger assembly consisting of an M90 roots-style supercharger and dedicated aluminum intake casting. The supercharger intake features long intake runners designed to optimize power (and torque) production up to 6,000 rpm. The supercharger would provide the additional airflow in the form of boost pressure, but the intake runner length is critical (in both NA and blown applications) for maximizing torque. Combining the immediate boost response of a positive displacement blower with optimized runner length makes for one impressive power curve. In addition to the blower, the motor was also equipped with a 70-mm Ford Racing throttle body, a smaller blower pulley to increase the boost pressure, and 36-pound injectors run by a F.A.S.T. engine management system. The SHM 4.6L was also equipped with a set of Kooks 1⅝-inch stainless steel headers, an electric water pump, and an MSD coil pack.
To illustrate the gains possible with a cam change on a supercharged application, I swapped out the stock PI cams for a set of Xtreme Energy 262H cams (actually designed for the non-PI heads). The main difference in the PI and non-PI cams is the lift value. The PI heads are set up to accept higher (.550 inch) lift cams than the non-PI (.500 inch) versions. The non-PI cams can be run in the PI heads with no trouble, but the reverse is not true without ensuring adequate retainer-to-seal and coil bind (valvespring) clearance. The XE262H cams offered .500 lift (both intake and exhaust) but a dual-pattern duration split. The intake featured 224 degrees of duration and 232 degrees of exhaust duration (@ .050). The wide 114-degree lobe separation angle ensured a broad curve and a relatively smooth idle given the durations specs. The Xtreme Energy cams worked fine with the stock valvesprings, though Comp does offer a valvespring upgrade for both the 2-valve and 4-valve modular motors.

 

 

 

 

Test 4: Vortech Supercharged Early 2-Valve GT: Comp Cams XE274H Camshafts

This supercharged cam comparison was actually a retest (of sorts) on the Comp 4.6L 2-valve cams used in Test 1. The idea was to demonstrate whether the XE274H cams originally designed for a naturally aspirated combination would work well on a supercharged motor. Due to a snafu with the stock Mustang PI cams (one was lost), I was forced to compare the XE274H cams to a set of 4.6L truck cams that I got at the last minute from Accufab’s John Mihovitz (at midnight no less – thanks John).

As with most of the testing run on the engine dyno, this modified 4.6L motor was tuned using the F.A.S.T. engine management system. In no way does that make the results less than applicable for street motors running the factory computer. Custom programming is readily available for the factory ECU and should be considered when installing any type of forced induction, whether modified or stock. I shudder to think of installing a supercharger or turbo on any motor and immediately taking it out on the street and stomping on the throttle. Detonation will kill even the strongest forged pistons, where proper tuning will allow you to run trouble-free for years. The F.A.S.T. system allowed us to run any size injector and run without the mass-air meter. Since we were primarily concerned with wide-open throttle tuning (and minor associated transition throttle), the F.A.S.T. system was definitely the way to go. Tom Habryzk from Westech had each combination up and running in no time. The procedure with the F.A.S.T. system was to load the motor at 3,000 rpm to check air/fuel. If the motor was lean at any throttle position, fuel was added via the fuel tables. The total timing was kept at a safe 18 degrees during tuning. This procedure was repeated at 3,500 rpm, 4,000 rpm, and then 4,500 rpm until we reached the maximum engine speed. Only after establishing a safe fuel curve did we load the motor and run a sweep test through the rev range.

 

 

 

 

Test 5: Naturally Aspirated ’03 4-Valve: Cobra Cams vs. Comp Cams XE262AH Camshafts

This test compares the stock ’03 Cobra cams and a set of Comp XE262AH cams. Though originally equipped with an Eaton supercharger, the low-compression ’03 Cobra crate motor was equipped with a 2001 Cobra intake manifold (and no supercharger). This cam setup was also tested with the Eaton and Kenne Bell superchargers, so be sure to check out Tests 7 and 8. To illustrate the gains offered in naturally aspirated trim, the motor was equipped with the F.A.S.T. management system, a Meziere electric water pump, and Flow-Tech long-tube headers (no mufflers). The motor was tuned for a 13.0:1 air/fuel ratio and 28 degrees of timing. The low-compression 4-valve motor produced 369 hp at 6,000 rpm and 377 ft-lbs of torque at 4,900 rpm. Equipped with the stock cams, the power curve pulled strong up to 5,000 rpm where it flattened out until 6,500 rpm. Despite the low compression, the torque output exceeded 350 ft-lbs from 3,600 to 5,400 rpm. Though this was pretty decent considering the low compression, I knew there was much more power to be had with the right set of performance cams. With the baseline tests out of the way, we tore into the Cobra motor to perform the cam(s) swap.

 

 

 

 

Test 6: 4-Valve Cobra: Degreeing Comp XE262AH Camshafts

 

 

 

Test 7: Eaton Supercharged ’03 4-Valve Cobra: Comp Cams XE262AH Camshafts

Like their selections for the 2-valve mod motors, Comp Cams offers a wide variety of different cam profiles. Not all 4-valve 4.6L motors (or their owners) 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; they even offer cam combos for supercharged and nitrous applications. The new Comp 4-valve modular 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 feature .425 inches of lift with duration figures ranging from 218 degrees to 234 degrees (@ .050). The remainder of the Comp offerings features a split lift of .475 inches (intake) and .450 inches (exhaust). The Xtreme XE-R series share 114-degree lobe separation angle, while the supercharged and nitrous cams feature slightly wider 116-degree lobe separation angles.

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This Tech Tip is From the Full Book, BUILDING 4.6/5.4L FORD HORSEPOWER ON THE DYNO. For a comprehensive guide on this entire subject you can visit this link:

LEARN MORE ABOUT THIS BOOK HERE

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Our first choice of cams for our supercharged ’03-’04 Cobra motor is one of the XE-R Supercharged and Nitrous grinds. Unfortunately, these cams required a valvespring upgrade that was not available to meet our dyno schedule. Rather than give up and reschedule the test, I decided to do the next best thing and proceed forward with cams that don’t require a spring upgrade. Basically, this meant some Xtreme RPM cams with only .425 inches of lift. The low lift figures allowed me to retain the stock Ford valvesprings without fear of coil bind. After looking over the four Xtreme RPM offerings, I chose the XE262AH cams. According to Comp, the XE262AH cams were designed to provide great street performance with significant horsepower and torque gains without computer modifications. For our F.A.S.T. engine management, the plug-n-play feature wasn’t as important, but it sure would be for the vast majority of Cobra owners running the factory ECU. 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 inches of lift (both intake and exhaust).

The first step was to run the ’03 Cobra crate motor with the stock cams and the Eaton M112 supercharger. The motor was equipped with the F.A.S.T. management system, a Meziere electric water pump, Accufab inlet and throttle body, and Flow-Tech long-tube headers (no mufflers). The motor was tuned to an 11.8:1 air/fuel ratio with 23 degrees of timing using a 7.5-inch crank pulley and a stock blower pulley (for 9.3 psi).

 

 

 

Test 8: Kenne Bell Supercharged ’03 4-Valve Cobra: Comp Cams XE262AH Camshafts

Test 8 is actually a continuation of Tests 5 and 7, as I compared the Comp XE262AH cams against the factory ’03 Cobra cams on an ’03 Cobra motor. The comparison was made in naturally aspirated trim (Test 5) as well as with the Eaton supercharger (Test 7). I also decided to test using a Kenne Bell twin-screw supercharger as I felt the Eaton blower may have been nearing its flow limit and that the more efficient (and powerful) twin-screw blower might show better improvements. Those eagle-eyed readers who have access to a Comp Cams catalog may have checked out the spec box and noticed that the supercharged cam offerings (like the XE262AH) for the 4.6L 4-valve motors are dual-pattern as well. The difference between the Xtreme RPM and XE-R Supercharged cams was that the supercharged versions featured more exhaust duration. Our XE262AH cams offered 4 degrees more intake duration (226 degrees versus 222 degrees), but the comparable supercharged cams featured a 2-degree split (224 degrees versus 222 degrees) skewed in favor of the exhaust. The XE262AH cams were selected out of necessity, as all of the larger (blower-specific) cams required a valvespring upgrade that was unavailable at the time of the dyno test.

A huge thanks goes out to Accufab’s John Mihovitz for providing the necessary tools for performing the cam surgery on our 4-valve Cobra motor. Without the valvespring compressor, custom piston stop (to precisely locate TDC), and associated components, we would never have been able to perform this 4-valve cam swap. While the main components are very similar to the 2-valve GT motor, the 4-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 required compressing and removing all 32 hydraulic lifters. The 4-valve cam swap was not terribly difficult, just time-consuming. Equipped with the stock cams, the Kenne Bell-supercharged ’03 Cobra motor produced 670 hp at 6,600 rpm and 578 ft-lbs of torque at 4,300 rpm. Stock cams or not, this was pretty impressive. Check out the chapter on 4-valve supercharging for a rundown on the gains offered by the Kenne Bell twin-screw blower over the stock Eaton.

 

 

Test 9: Kenne Bell Supercharged ’03 4-Valve Cobra: Crower Stage 2 Camshafts

Rather than testing the Crower Stage 2 cams on a stock ’03 Cobra motor, I decided to try them on something a bit more powerful – an ’03 Cobra equipped with a Kenne Bell blower upgrade. Though no internal mods were performed to the 4-valve motor, the Cobra did feature a Kenne Bell cold-air intake system, the stock 90-mm mass-air meter, and an Accufab single-blade throttle body and elbow. Given the additional power potential of the modified mod motor, the stock injectors were ditched in favor of a set of 60 pounders fed through ½-inch fuel line by a pair of stock Cobra fuel pumps augmented with a Kenne Bell Boost-A-Pump. During high-boost testing, the motor was run with C16 race fuel, but runs daily on 91-octane pump gas. This Kenne Bell supercharged street car has run in the 9s!
With all that supercharged power forcing its way into the motor, it was imperative to get it all out as well. The exhaust system consisted of a set of Kooks headers, high-flow cat pipe, and a Bassani cat-back exhaust system. In a quest for improved ETs, the Cobra-exclusive independent rear suspension was replaced with a standard-issue solid rear axle featuring 3.55:1 gears. The stock tranny has held up to the abuse but the stock clutch was upgraded with a Center Force Dual-Friction setup with matching steel flywheel. Using the new Superchips Custom Tuning Advantage software, a Kenne Bell custom chip was used to dial in the combination with 23 degrees of total timing and a steady air/fuel mixture of 11.7:1. With the stock Cobra cams, the engine produced peak numbers of 618 hp and 642 ft-lbs of torque at a maximum boost pressure of 25.6 psi (to the rear wheels). This peak reading was recorded at 5,500 rpm, as ignition misfire caused some problems with high-RPM power readings. As we have come to expect of twin-screw supercharged Cobra motors, the torque curve was every bit as impressive as the power curve. The KB-augmented ’03 thumped out more than 600 ft-lbs of torque from below 2,900 rpm to 5,500 rpm. Imagine what 600+ ft-lbs of torque feels like at 3,000 rpm.

 

 

 

Test 10: PI 2-Valve GT: Crane Cams HR-212/550-25-15 Camshafts

The key to successfully choosing a cam profile is to choose one that’s designed for a specific operating range. Given that most street 4.6L 2-valve Mustangs operate over a wide RPM range (from say 1,500 rpm to 6,000 rpm), it would be nice to have cams that optimize power production in this 4,500-rpm power band. Unfortunately, no cam profile can offer this type of power band. The very best we can hope to achieve is to minimize the tradeoffs associated with the power gains we seek. The stock PI cams offer a nice compromise. It’s important to point out that the factory didn’t choose the cam profile solely for its power band, but rather for its combination of peak and average power production, emissions output, and cycle life (or longevity). With so many design variables, it’s only natural to assume that the stock cam profiles can be improved upon. The stock profiles are pretty tough to beat in the lower rev ranges, but it’s possible to dramatically enhance midrange and top-end power without sacrificing too much down low. In the case of the Crane cams tested on our Sean Hyland mod motor, the tradeoff was skewed way in favor of the additional power.

With daily street use in mind, we selected the mildest cam profiles available from Crane. To properly illustrate the merits of a set of street performance cams, we’ll be testing the Crane Cams HR-212/550-25-15 grinds for the 4.6L PI 2-valve motor. The HR-212/550-25-15 cams offer .550 inches of lift for both the intake and exhaust with dual-pattern duration figures. Given that the intake ports of the PI heads easily outflow the exhaust ports, the HR-212/550-25-15 cams offered 212 degrees of intake duration and 218 degrees of exhaust duration. With the cams installed (as recommended by Crane) at 110 degrees (intake) and 120 degrees (exhaust), this left the lobe separation at an idle-friendly 115 degrees.

 

 

 

 

Written by Richard Holdener and republished with permission of CarTech Inc

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