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4.6L / 5.4L Camshafts
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.
Degreeing the camshafts on a Ford 4.6L DOHC engine
Degreeing the cams is every bit as
important as a cam swap. Advancing
and retarding the cams can yield huge
power gains. It’s time consuming, but
ultimately worth it.
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
loose 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!
An assortment of Ford 4.6L Camshafts
As difficult as cam swaps are on
modular motors, what better way to
illustrate the differences offered by six
different cam profiles than to perform
six different cam swaps on the engine
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.
Changing Camshafts on a Ford 4.6 SOHC engine
The 2-valve cams are a tad easier
than the 4-valve swap, but once you’ve
performed the procedure once or
twice, it isn’t any more technically
difficult than a standard 5.0L V-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.
Crower Stage 2 cams for a Ford 4.6L DOHC engine
These Crower Stage 2 cams offered a
sizable power gain over the stock ’03
Cobra cams on a Kenne Bell
supercharged 4-valve.
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.
Dyno testing graph of early 4.6L Mustang GT cams verses comp cam
Early GT Cams vs. Comp XE274H
Stock Early GT Cams:
260 hp @ 5,000 rpm

Comp XE274H Cams:
301 hp @ 5,000 rpm
Largest Gain: 53 hp @ 5,300 rpm
Stock Early GT Cams vs. Comp XE274H Cams (Horsepower)
These are the kinds of power gains you dream about when installing
performance cams. The Xtreme Energy XE274H cams from Comp
Cams added as much as 53 hp to the otherwise stock non-PI 4.6L.
Dyno testing torque chart of a Ford 4.6L early Mustang GT camshaft compared to comp cams Early GT Cams vs. Comp XE274H
Stock Early GT Cams:
342 ft-lbs @ 3,500 rpm

Comp XE274H Cams:
346 ft-lbs @ 4,100 rpm
Largest Gain: 52 ft-lbs @ 5,300 rpm
Stock Early GT Cams vs. Comp XE274H Cams (Torque)
Note from the torque curve that the wilder cam profiles cost
some torque below 3,400 rpm, but significant gains were
achieved from 3,500 to 5,500 rpm. The Xtreme Energy
cams allowed this early 4.6L to produced PI power and
torque numbers.
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This has been a sample page from

Building 4.6 / 5.4L Ford Horsepower on the Dyno Building 4.6/5.4L Ford
Horsepower on the Dyno
by Richard Holdener
The 4.6- and 5.4-liter modular Ford engines are finally
catching up with the legendary 5.0L in terms of aftermarket
support and performance parts availability. Having a lot of
parts to choose from is great for the enthusiast, but it can
also make it harder to figure out what parts and modifications
will work best. Building 4.6/5.4L Ford Horsepower on the
Dyno takes the guesswork out of modification and parts
selection by showing you the types of horsepower and torque
gains expected by each modification.

Author Richard Holdener uses over 340 photos and 185
back-to-back dyno graphs to show you which parts increase
horsepower and torque, and which parts don’t deliver on
their promises. Unlike sources that only give you peak
numbers and gains, Building 4.6/5.4L Ford Horsepower on
the Dyno includes complete before-and-after dyno graphs,
so you can see where in the RPM range these parts make
(or lose) the most horsepower and torque. Holdener covers
upgrades for 2-, 3-, and 4-valve modular engines, with
chapters on throttle bodies and inlet elbows, intake
manifolds, cylinder heads, camshafts, nitrous oxide,
supercharging, turbocharging, headers, exhaust systems,
and complete engine buildups.
Click below to view sample pages
Chap. 1 - Throttle Bodies
Chap. 2 - Intake Manifold
Chap. 3 - Cylinder Heads
Chap. 4 - Camshafts
Chap. 5 - Nitrous Oxide
Chap. 6 - SOHC Supercharging
Chap. 7 - DOHC Supercharging
Chap. 8 - Turbocharging
Chap. 9 - Engine Headers
Chap. 10 - 4.6 Engine Buildups
8-1/2 x 11"
208 pgs.
340+ b/w photos
Item # SA115P
Price: $28.95
This is a great book and a
must have for anyone
considering modifying a 4.6 or
5.4 Ford for more power!
Click here to buy now!

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