Two-Valve Twist: Trick Flow Heads Add 100 Extra Horses to a 4.6L 2V

Trick Flow applied its famous Twisted Wedge combustion chamber design (left) to the Modular head. The 1.840-inch intake valves were moved to the opposite (intake) side of the head. This puts the valves directly in line with the intake ports, creating the “twisted” combustion chamber design so conducive to airflow. The spark plugs were moved closer to the center of the chamber for improved combustion. The Twisted Wedge design accommodates cams up to 245-degree duration @ .050 and .600 inches of lift, a significant improvement over the stock 4.6L heads.

This cutaway shows the 185cc intake runner. The Twisted Wedge heads have as-cast runners based on CNC-ported profiles developed by Trick Flow. These Fast As Cast runners provide very high levels of airflow without the expense of actual CNC machining. That helps keep the Twisted Wedge heads affordable. The spark plug hole is threaded 3/4 inches to keep the plug in place, even under high boost.

The factory Modular head (right) has cast-in cam journals—the cams ride directly on the journals without bearings. While cost-effective, the design means a valvetrain failure can wipe out both cams and journals, reducing the heads to scrap. Trick Flow developed removable 4-bolt billet journals for the Twisted Wedge (left). They keep the cams stable at high rpm and can be easily replaced if bad things damage them.

We won’t go into the whole dis-assembly procedure here—that’s what service manuals are for. With the top-end, the front timing chain system, and the camshafts removed, the factory PI heads on this 2002 4.6L can be removed.

The stock head bolts are torque-to-yield and cannot be reused. Since the 4.6L will be doing service as a Trick Flow development mule, there will be lots of head-swappin’ going on. ARP cylinder head studs (left) will make the process a littler easier. The studs have the added benefit of being stronger—just in case there’s a blower or something in the future. Keep in mind that head studs are not easily removed when the engine is installed in the vehicle.

ARP head studs and a Fel-Pro head gasket are in place and ready to accept a new Twisted Wedge 185 cylinder head. While the front cover and cam drive have to be removed for a head swap, the water and oil pumps can stay in place as shown.

The head stud nuts are torqued to manufacturer’s spec with moly lube. You can get a good look at the billet cam journals; they look a lot like four-bolt main bearing caps, don’t they? Note that the Twisted Wedge 185 heads are drilled for both Romeo- and Windsor-style valve covers.

The cam journals were slathered in Royal Purple synthetic break-in lube in preparation for the Trick Flow Track Max roller camshaft. The Track Max offers 228/230-degree duration at .050 and .550 inches of lift, plus a meaty power curve from 1,500 to 5,000 rpm. Trick Flow says the Track Max cams will work on stock Ford PI heads, but only with the company’s valve spring upgrade kit and close attention paid to piston-to-valve clearance. The cam journal caps get torqued to 12.5 ft.-lbs.

Ford charges an arm and a leg for a 4.6L replacement timing set. Trick Flow offers an OE quality timing set that won’t cost you any body parts at all. The set comes with both the all-plastic PI and steel-backed plastic, non-PI chain guides. Most people convert to the PI guides.

Trick Flow offers timing sets with non-adjustable crank gears or these cool adjustable crank gears. The billet steel gears allow you to advance or retard the cams in two-degree increments, up to a total of eight degrees in either direction.

Degreeing cams on a 4.6 or 5.4 2V engine is not any harder than degreeing a “regular” single cam V8—you just do everything twice. Cam timing can be different between each cylinder bank; one cam may be advanced or retarded relative to the other, which can cost you horsepower. Trick Flow’s adjustable crank gears let you treat each cylinder bank almost like a separate engine, allowing you to set cam timing to produce optimum power.

All sorts of Trick Flow goodness here. Up top is the Track Heat intake manifold. It’s made of A319 aluminum to handle the extra pressure of nitrous or superchargers (the factory plastic intake likes to break into little pieces when you put the juice to it). The Track Heat improves power in the 1,500 to 7,500 rpm range, making it an ideal companion for the Twisted Wedge 185 heads. The round blue thingy on the front is an SFI 18.1-rated Track Max harmonic damper that, er, dampens harmful crankshaft harmonics. Covering the cams is a pair of Trick Flow’s cast aluminum valve covers. The lightweight covers won’t crack or distort like OE plastic covers, and feature a baffled PCV connection plus threaded and baffled fresh air connections for supercharged applications.

The fuel rails and injectors are pushed into place. The rails are OE, but the injectors are Trick Flow TFX squirters, rated at 30 lbs./hr. versus the factory 19 lbs./hr. units. The extra fuel delivery is needed to take advantage of all the extra airflow the Trick Flow components offer.

Compared to the factory pintle-style injector on the left, the TFX injector’s disc nozzle flows more fuel, promotes better fuel atomization, and is less prone to clogging. The TFX injectors also feature low magnetic stainless steel bodies to resist corrosion, 1/2 micron filter screens, Viton O-ring seals, and OE type wiring connectors and fuel rail clip grooves.

A Trick Flow TFX 75mm throttle body is fitted to the Track Heat manifold’s upper plenum. The die-cast aluminum throttle body has hand-fitted butterflies for smooth, precise operation with no air leakage. The ignition coils are MSD Blasters.

The dyno confirms the fruit of Trick Flow’s labors—almost 408 peak horsepower at 6,500 rpm and 348 ft.-lbs. peak torque at 5,500 rpm. Since the 4.6 is at heart a midrange and top end power maker, the horsepower curve doesn’t really start climbing until 4,000 rpm or so. Torque production gets into serious swing around 2,500 rpm. Put this combination in a Mustang and you’ll have plenty of grunt to scoot away from a traffic light—and enough top end to beat everybody to the next one. Not that we condone that sort of behavior…