Richard Holdener
June 28, 2007

When you go looking to make serious power from your modular Ford engine, there's no better or easier route than forced induction. If you're looking to produce somewhere between 300 hp and 400 hp (flywheel), a normally aspirated 4.6L might be the way to go, but if you want to exceed that number, things start to get a little tougher.

The fact is, the 4.6 sports just 281 ci, and if you want serious N/A power, you'll have to add lots of compression and rev it to the moon. While it can be done, this generally isn't the ticket for a load of fun in a 3,500-pound street Mustang, unless you dig having 4.88 gears out back.

We know what you're thinking-we've exceeded that number by a fairly wide margin in previous testing, but there's a big difference between a supercharged motor producing even 400 hp and a normally aspirated combination running the same power level. In almost all cases, the supercharger (or turbocharged) combination will produce significantly more torque than its normally aspirated counterpart, this despite similar peak power numbers. Case in point, our 400hp supercharged combination pumped out a solid 35 extra foot-pounds compared to a comparable 400hp N/A combination. Things get even more one-sided when the power levels start climbing. That's because with forced induction the engine can swallow far more air and burn more fuel through the lower rev range.

We weren't trying to demonstrate absolute numbers but rather different recipes for reaching a desired goal. Was there more power to be had from these combinations? You bet, as with almost all forced-induction applications, additional power was only more boost away, but so too was it available by altering the specific combination.

Starting with the 400hp mark, we supplied recipes for producing 400 hp, 500 hp, 600 hp, and even 700 hp from your 4.6L motor. Used in whole or part, these force-fed foursomes should help steer you in the right direction.

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400hp 4.6L FRPP Supercharger (7 psi)

This 4.6L Two-Valve combination included a complete engine supplied by Sean Hyland Motorsport. Built as a test motor, the 4.6 featured forged internals, including a Cobra crank, forged rods, and pistons. The pistons were selected to duplicate the stock compression ratio when com-bined with the factory PI heads. The SHM long-block was upgraded with a set of XE262H (non-PI) cams from Comp Cams as well as a set of Kooks long-tube headers. In normally aspirated trim, the mild PI combination produced 297 hp and 344 lb-ft of torque. Torque production exceeded 300 lb-ft from 2,500 rpm all the way to 5,100 rpm. After adding the FRPP supercharger (no intercooler), 70mm throttle body, and 3.4-inch blower pulley (up from the standard 3.6 inches), the SHM PI motor produced 427 hp and 425 lb-ft of torque. Torque production now exceeded 400 lb-ft from 3,200 rpm to 5,000 rpm at a maximum boost level of just 7 psi. Obviously, there's a great deal more power left in this combination with ported heads, higher boost, and even wilder cam timing.

Specs: 400 hp
Block:Stock '00 4.6L Two-Valve iron
Crank:Stock '00 4.6L Four-Valve Cobra steel (stock stroke)
Rods:SHM forged
Pistons:SHM forged-stock
Compression:9.5:1
Cylinder Heads:Stock '00 4.6L 2V PI
Cams:Comp Cams XE262H
Intake Manifold:'00 4.6L Two-Valve PI
Throttle Body:Accufab 75mm (N/A), FRPP 70mm (SC)
Inlet Elbow:Accufab
Injectors:19 lbs N/A, 36 lbs SC
Management System:FAST
Headers:Kooks 1-5/8 in
Exhaust:18-in collector extension
Fuel:91- and 100-octane Rockett Brand racing fuel
Blower:FRPP Two-Valve Roots-style
Blower Pulley:3.4 in
Intercooler:N/A
Boost:6.9 psi

500hp 4.6L Kenne Bell Supercharger (9 psi)

This buildup began as a '98 Two-Valve motor with more than its fair share of miles. The high-mileage but otherwise stock short-block was topped off with a set of ported PI heads from Total Engine Airflow. The power potential was further improved with a set of XE274H (non-PI) cams from Comp Cams, a 75mm Accufab throttle body, and 1-5/8-inch Hooker headers. Installing the PI heads on the non-PI short-block increased the static compression by nearly a full point. The result of all these modifications was a normally aspirated Two-Valve motor that produced 407 hp and 393 lb-ft of torque. After replacing the factory PI intake with a Kenne Bell 1.7L twin-screw blower running 9 psi of boost, the peak power numbers jumped to 574 hp and 513 lb-ft of torque.

As we have come to expect, torque production was impressive with the positive-displacement twin-screw blower. The torque production exceeded 500 lb-ft from 3,700 rpm to 5,700 rpm, making for one sweet powerband. As with the FRPP combination, the Kenne Bell blower had significantly more power to offer with increased boost pressure. Though the Kenne Bell blower kit included an air-to-water intercooler, after testing we were a little concerned about the strength of the factory cast pistons. If you want to produce near 600 hp, it's best to step up to some forged internals-at least pistons and rods.

Specs: 500 hp
Block:Stock '98 4.6L Two-Valve iron
Crank:Stock '98 4.6L Two-Valve iron (stock stroke)
Rods:Stock '98 4.6L Two-Valve iron
Pistons:Stock '98 4.6L Two-Valve iron
Compression:10.6:1
Cylinder Heads:TEA CNC-ported PI
Cams:Comp Cams XE274H
Intake Manifold:'00 4.6L Two-Valve PI
Throttle Body:Accufab 75 mm (both N/A and SC)
Inlet Elbow:Accufab
Injectors:36 lbs N/A, 65 lbs SC
Management System:FAST
Headers:Hooker 1-5/8 in
Exhaust:18-in collector extension
Fuel:91- and {{{100}}}-octane Rockett Brand racing fuel
Blower:Kenne Bell 1.7L twin screw
Intercooler:Kenne Bell air-to-water (ambient dyno water used for testing)
Boost:9 psi (8.3 psi at power peak)

600hp 4.6L Vortech Supercharger (12 psi)

Things start to get serious when you try to exceed 600 hp from a Two-Valve 4.6L. Though our combination was sporting nothing more than the factory '98 short-block, running on the engine dyno gave us complete control over every variable, making this level of power production safer than it might be on the street. Naturally, this high-compression, relatively high-boost motor was run with 100-octane Rockett Brand racing fuel. As with all of our test motors, the crankcase was also filled with Lucas synthetic (5W-30) oil. For this test with the Vortech T-Trim blower, we relied on the same test motor as the 500hp Kenne Bell combination. The '98 Two-Valve motor was equipped with the CNC-ported PI heads from Total Engine Airflow, XE274H (non-PI) cams, and factory PI intake. Running a 75mm Accufab throttle body and Hooker headers, the 4.6L produced 407 hp and 393 lb-ft of torque. Rather than run the standard S-trim supercharger, we stepped up to the T-Trim head unit. Vortech also supplied one of its charge cooler systems to help lower the inlet charge temperature, a necessity with our static compression exceeding 10.0:1. Running 20 degrees of timing and a 3.33-inch blower pulley, the Vortech T-Trim pumped out 12 psi of boost, which helped the modified 4.6L produce 654 hp and 547 lb-ft of torque.

Specs: 600 hp
Block:Stock '98 4.6L Two-Valve iron
Crank:Stock '98 4.6L Two-Valve iron (stock stroke)
Rods:Stock '98 4.6L Two-Valve iron
Pistons:Stock '98 4.6L Two-Valve iron
Compression:10.6:1
Cylinder Heads:TEA CNC-ported PI
Cams:Comp Cams XE274H
Intake Manifold:'00 4.6L Two-Valve PI
Throttle Body:Accufab 75mm (both N/A and SC)
Inlet Elbow:Accufab
Injectors:36 lb N/A, 65 lbs SC
Management System:FAST
Headers:Hooker 1-5/8 in
Exhaust:18-in collector extension
Fuel:91- and 100-octane Rockett Brand racing fuel
Blower:Vortech T-Trim
Intercooler:Vortech air-to-water (ambient dyno water used for testing)
Boost:12 psi (at power peak)

700hp HP twin

While it would have been nice to run the HP twin-turbo kit on the same impressive Two-Valve long-block, we built a dedicated motor for this combination. The factory '98 short-block was upgraded with a set of forged rods and pistons from Coast High Performance. The CHP kit also included a steel Cobra crank. The TEA heads were replaced with a set of CNC heads from Ford Performance Solutions. The CNC porting by FPS was applied to a set of early 2V (non-PI) heads. The early heads were then modified to allow use with the later PI intake without need of an adapter. While the PI heads are ultimately a better and more powerful choice, this conversion was an interesting alternative. The heads were equipped with a set of SI valves, a pair of XE262AH (PI-spec) cams from Comp Cams, and the PI intake. Running through an Accufab throttle body and the Hooker headers, the N/A Two-Valve motor produced 347 hp and 350 lb-ft of torque. After the twin-turbo kit installation-including a pair of 57mm turbos and an air-to-air intercooler-the peak power jumped to 713 hp and 717 lb-ft of torque. Running just 13.7 psi, this 700hp Two-Valve combination was plenty stout and was (like the other blower combinations) easily capable of significantly more.

Specs: 700 hp
Block:Stock '98 4.6L Two-Valve iron
Crank:Stock '00 4.6L Four-Valve Cobra steel (stock stroke)
Rods:CHP forged
Pistons:CHP forged
Compression:9.3:1
Cylinder Heads:FPS CNC-ported non-PI
Cams:Comp Cams XE262 AH
Intake Manifold:'00 4.6L Two-Valve PI
Throttle Body:Accufab 75mm
Inlet Elbow:Accufab
Injectors:36 lbs, 65 lbs
Management System:FAST
Headers:Hooker 1-5/8-in
Exhaust:Dual 2-1/2-in from turbos no mufflers
Fuel:91- and 114-octane Rockett Brand racing fuel
Turbos:HP Performance twin-turbo kit (dual 57mm turbos)
Intercooler:HP Performance air-to-air
Boost:13.7 psi