John Hedenburg
March 14, 2003

The 4.6-liter Modular engines have powered the Ford Mustang for eight years now, and surprisingly there are only two aftermarket intakes available (both of which are from Ford Racing). This should lead astute Mustangers to conclude either the stock manifolds are just that good, or an aftermarket intake is not a viable item for aftermarket manufacturers to produce. We think the answer lies somewhere in the middle.

Both models of the 4.6 engines feature intricate intake systems with manifolds that have relatively complicated designs, but shouldn't be a brick wall in this technically advanced era. Perhaps the aftermarket thinks Mustang owners don't buy parts. Well, we certainly know that is not the case.

The four-valve units are cast from aluminum and have long runners to supply air at high velocity throughout the entire rpm range. To accomplish this, air enters the manifold at the throttle body located on the passenger side of the engine. The airflow is fed to a large plenum area in the center/bottom of the intake. Air is pulled into the individual runners that begin in the valley between the heads and swoop up and over the top to meet the individual ports in the cylinder heads.

The two-valve manifold found on GTs also sports long-arc-shaped runners, but it is formed from plastic. On GT intakes air is fed through a smaller throttle body, and the intake opening is located at the top/center of the manifold. Airflow through the GT intake follows through long runners on the way to the cylinder heads. Both designs have provisions to mount the injectors and fuel rails, thermostat, EGR valve, vacuum lines, throttle body, and a few brackets, too.

As you can see, any aftermarket intake must have provisions for all these accessories, it must bolt up clean to the heads, and equally important, it must make more power than stock. If the intake can't meet these requirements, what is the point of installing it?

Fortunately, we've heard rumblings from aftermarket manufacturers who are up to the task and are tooling up to produce some wild intakes for both 2V and 4V engines. But as of right now, none is available. This leaves owners who want to boost performance with either the '01 Bullitt intake or the Ford Racing High Flow manifold kit (PN M-9424-E46) for 2V models or the Ford Racing 4V kit (PN M-9424-T46) designed from the FR500.

Bullitt Blast
Performance enthusiasts know one way to increase power is to improve the airflow to the engine. If you own a 4.6 2V, it means installing an '01 Bullitt intake manifold. Unlike the plastic intakes found on all '96-present GT models, the '01 Bullitt manifold is cast aluminum which gives it some advantages--first, because it can be ported, and second, because if you run nitrous, there is a much smaller chance of blowing the thing into a million pieces should your engine encounter a dreaded nitrous backfire. Another attribute is the shorter, yet larger, runners. If there is a downside, it is the weight. The Bullitt intake weighs about 35 pounds, which is about twice the weight of the plastic one.

Our '01 project Stang happens to be sporting a Vortech V-2 SQ with a Vortech aftercooler, and horsepower is in the 360 range at the tires. Recently, we installed a free-flowing BBK exhaust, and while we could still turn up the boost (we're only running 10 psi), we decided to first give the 4.6 more flow via a better intake. And that means slipping a Bullitt intake in place of the stocker.

After scoring a new intake from our friends in Dearborn, we had the unit hogged-out by Extrude Hone for some extra potential. We then turned to the gang at JDM Engineering in Freehold, New Jersey, for the install. Jim D'Amore and crew were kind enough to stop working on those Lightnings and new Cobras to fit us in. Master tech Shaun Lacko and I got the project underway by disconnecting the battery and draining the coolant from the aftercooler and the engine cooling system. Meanwhile, Jim D'Amore placed a call to Joe Amato at Downs Ford in Tom's River to obtain the necessary parts to complete the swap.

While the manifold exchange is relatively simple, a host of parts must be relocated and/or changed over. In this, part one, we'll go as far as removing the original parts and to preparing the Bullitt manifold for duty. In part two we'll complete the install, then we'll hop in with D'Amore and tune this puppy for maximum power.

0305mm_LDzoom 2001_Ford_Mustang_GT Rear_Side_Track
Prior to adding the custom graphic package on Project Ice Box, we cut loose on the road course and on the dragstrip. And while our GT scoots on the track (12.38 at 115 on radials), we can always use extra horsepower.
0305mm_01zoom 2001_Ford_Mustang_GT Underhood_Supercharged_Engine
In its current trim, our Vortech supercharged 4.6-liter Mod mill developed over 370 hp at the wheels. Our goal is to raise the power level as high as possible without scattering the powdered metal connecting rods all over the place.
0305mm_02zoom 2001_Ford_Mustang_GT Interior_Disconnecting_Battery
Before doing anything, we disconnected our trunk-mounted battery.
0305mm_03zoom 2001_Ford_Mustang_GT Underhood_Installing_Strut_Brace
Supertech Shaun Lacko dove under the hood and started removing parts. He began with the strut-tower brace.
0305mm_04zoom 2001_Ford_Mustang_GT Undercar_Draining_Coolant
Then he drained the coolant from the radiator and the aftercooler system.
0305mm_05zoom 2001_Ford_Mustang_GT Underhood_Disconnecting_Intake_Tube
After disconnecting the bypass valve, he removed the supercharger inlet tube.
0305mm_06zoom 2001_Ford_Mustang_GT Underhood_Removing_Intercooler
Lacko then pulled away the Vortech aftercooler and hoses. The aftercooler will be replaced with a new unit designed specifically for the Bullitt intake.
0305mm_07zoom 2001_Ford_Mustang_GT Underhood_Disconnecting_Fuel_Injector_Harness
There are no spark plug wires or a distributor to fuss with on the 4.6 engine. Only the harness for the coil packs and injectors need to be disconnected.
0305mm_08zoom 2001_Ford_Mustang_GT Underhood_Removing_Alternator_Harness
This is the upper alternator bracket. It, along with the alternator, will be removed, and a new Cobra alternator will be installed. The Cobra unit is thinner and will clear the larger intake.
0305mm_09zoom 2001_Ford_Mustang_GT Underhood_Removing_Coolant_Hose
Next, the upper radiator hose was removed...
0305mm_10zoom 2001_Ford_Mustang_GT Underhood_Removing_Thermostat_Housing
...along with the thermostat housing and the thermostat.
0305mm_11zoom 2001_Ford_Mustang_GT Underhood_Removing_Coil_Packs
We then removed the coil packs to prevent them from being damaged, and because he wanted to install new spark plugs in the engine.
0305mm_12zoom 2001_Ford_Mustang_GT Underhood_Removing_Fuel_Line_Clip
This is the safety clip on the fuel line. It was pulled off so we could remove the lone fuel line.
0305mm_13zoom 2001_Ford_Mustang_GT Underhood_Removing_Fuel_Line
Using a fuel-line removal tool, Lacko disconnected the fuel line. Always use caution when working with fuel, especially on high-pressure, fuel-injected engines.
0305mm_14zoom 2001_Ford_Mustang_GT Underhood_Removing_Vacuum_Line
Next, we got some of the vacuum lines out of the way.
0305mm_15zoom 2001_Ford_Mustang_GT Underhood_Removing_Throttle_Cable
The kit includes new throttle and cruise control cables, so naturally, you must take the old ones off.
0305mm_16zoom 2001_Ford_Mustang_GT Underhood_Removing_EGR_Tube
Lacko then removed the EGR tube which runs from the EGR valve to the exhaust system.
0305mm_17zoom 2001_Ford_Mustang_GT Underhood_Removing_EGR_Tube
The tube must be snaked out from the top.
0305mm_18zoom 2001_Ford_Mustang_GT Underhood_Removing_Manifold_Bolts
Moving right along, we removed the manifold bolts.
0305mm_19zoom 2001_Ford_Mustang_GT Underhood_Removing_Alternator
Then the alternator was disconnected and removed.
0305mm_20zoom 2001_Ford_Mustang_GT Underhood_Removing_Manifold
Once the alternator was out of the way and the manifold bolts were removed, Lacko could lift the intake manifold off the engine.
0305mm_21zoom 2001_Ford_Mustang_GT Underhood_Heads
With the manifold removed you can see the heater tube that sits in the valley. This tube supplies coolant to the heater core to warm occupants on those cold days. Unfortunately, the standard 4.6 GT tube interferes with the Bullitt intake, so you must install a tube designed for the Bullitt system.
0305mm_22zoom 2001_Ford_Mustang_GT Underhood_Heads_Intake_Ports_Taped
The Bullitt tube runs down the middle of the valley and sits much lower, too. It exits at the back and to the left. You can also note that we covered the ports to prevent any debris from falling in and damaging the engine.
0305mm_23zoom 2001_Ford_Mustang_GT Underhood_Heater_Hose
With both tubes in place you can see how the standard GT tube and heater hose is aligned.
0305mm_24zoom 2001_Ford_Mustang_GT Underhood_Heater_Hose
In order to make it work, we cut the stock heater hose and attached it to the new tube.
This is the majority of the parts needed to complete the swap.
There are many differences between the two manifolds which can make the swap very difficult if you don't have all the parts and pieces. From this top view you can see the throttle bodies and EGR valves sit in completely different locations and the series of vacuum lines connect in different locations, as well. The swap also requires a different alternator, valve covers, fuel lines, etc.
Lacko disassembled the stock intake so we could pirate the injectors.
Even the fuel rails must be replaced because the feed is in a different location. Next month, we'll assemble the Bullitt manifold with our injectors and the new rails and we'll install it on Project Ice Box. And even though things are down right cold, even icy, here in New Jersey, that won't stop us from getting the Mustang tuned, on the dyno, then on the race track.