Tech / Tech Articles

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

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Trick Flow’s Twisted Wedge 185 cylinder heads are available with 38cc or 44cc combustion chambers that deliver about 10:1 compression on the appropriate short block (38cc/1998-up PI, 44cc/1996-98 non-PI). The heads come fully assembled with valves, valve springs, locks, retainers, and valve seals.

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…

For owners of Ford 4.6L and 5.4L Two-Valve modular V8s, the wait for a true performance cylinder head ended in 2009. That’s when Trick Flow Specialties introduced the Twisted Wedge 185 aluminum cylinder heads. They were the first true aftermarket performance heads for the Two-Valvers.

There are gazillions of Two-Valve engines available for cheap in the nation’s bone yards. The short blocks can handle up to 450 horsepower with no modifications. Camshafts, induction systems, headers, superchargers, and other hop-up parts are on the shelves. Add in the airflow provided by the Trick Flow heads and you have the perfect storm of serious Two-Valve horsepower.

The Return of the Twisted Wedge
The Twisted Wedge name was first used for Trick Flow’s groundbreaking 5.0L aluminum heads, introduced in 1995. (Those heads are still available in myriad versions for street and drag racing). The name describes Trick Flow’s patented combustion chamber design, which rotates, or twists, the intake and exhaust valve angles and moves the spark plug closer to the center of the cylinder bore. These changes unshroud the valves to increase airflow volume and help promote more complete combustion.

Trick Flow took a similar approach with the Twisted Wedge 185 heads. Ford’s design put the valves single-file on the exhaust side of the head, which greatly restricts airflow. This design also limits camshaft size due to valve-to-piston clearance with the factory dished pistons. Trick Flow engineers moved the intake valves to the opposite (intake) side of the head. This put them directly in line with the intake ports and created the “twisted” combustion chamber design so conducive to airflow. The design also accommodates wide cams up to 245 degrees duration @ .050 and .600 inches of lift with wide lobe separation angles (LSA), and mid- 230 degree duration cams with narrower LSAs. That is a significant improvement over the stock 4.6L heads.

The Twisted Wedge 185 heads retain the port shapes and locations of the factory Power Improvement (PI) heads, so PI-compatible intakes and headers can be used. However, Trick Flow opened up the intake runners to 185cc and recontoured them to smooth out the airflow path. The intake and the 93cc exhaust runners are as-cast, but are based on CNC-ported profiles. These Fast As Cast® runners provide high flow rates without the expense of actual CNC-porting. The process is a Trick Flow exclusive.

The Twisted Wedge 185 heads have another “why didn’t we think of that” feature: removable cam bearing journals. Factory 4.6L heads have cast-in journals with a removable cap (Windsor) or a removable cap “girdle” (Romeo). The cams ride directly on the journals. If the valvetrain lets go and the journals are damaged, the heads turn into aluminum doorstops. Trick Flow developed a forged powdered metal, four-bolt cam journal precisely located on the head and completely removable. If the caps are ever damaged, you can ring up Trick Flow for a set of replacements and put your Twisted Wedge heads back into service.

The Twisted Wedge 185 heads are available with your choice of 38cc or 44cc CNC-profiled combustion chambers with 1.840/1.450 inch stainless valves. The 38cc chambers yield about 10:1 compression on a PI short block; the 44cc chambers deliver the same compression ratio for non-PI (1996-98) short blocks.

The heads come fully assembled with stainless valves, 1.100-inch beehive valve springs, chromemoly retainers, and forged steel locks. The standard Twisted Wedge 185 heads come with springs rated at 90 lbs. seat/205 lbs. open pressure. The springs can handle up to .600 inches of valve lift. Trick Flow also offers the Twisted Wedge Track Heat® 185 with stiffer springs (125 lbs. seat/275 lbs. open pressure) for engines with higher compression or a power adder like nitrous and superchargers.

To demonstrate the horsepower awesomeness designed into the Twisted Wedge 185 heads, Trick Flow bolted a pair on a 50,000-mile Two-Valver from a 2002 Mustang GT. To take advantage of the extra airflow, Trick Flow also added one of its Track Max Stage One cam sets, a Track Heat intake manifold, 30 lb.-hr. TFX fuel injectors, an SFI-approved harmonic damper, and a timing chain kit with adjustable crank gears. The net worth of all this stuff is around 408 horsepower—over 100 horsepower more than a stock 4.6L Two-Valve delivers. That’s a big check mark in the win column.

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  1. Have a 2003 Ford truck, F-250 with 100,000 mi. and the cylinder heads need some help, do you have stock exchange for a stock bottom end. Please contact me at your earliest convenience at 724-496-2921. Thanks again for your time and help.Sincerely John T Elliott

  2. Pingback: Trick Flow heads, clearances - Ford Mustang Forums : Mustang Forum

  3. Pingback: Trick Flow headers on a 4.6L - : Factory Five Racing Discussion Forum

  4. I want to get my heads ported and polished on my 97 cougar xr7 with a 4.6l 2V SOHC. Would the same heads made for a GT work for my motor?

    • DrZerker says:

      Yes, the TF heads will work. Check out

    • OnAllCylinders says:

      With so many new parts recently, it is possible but unlikely any of those parts are at fault. It sounds like a possible bad rubber flex hose or a rusty steel line that has failed coincidentally. Without further investigation, there is really no reason to suspect faulty installation.

  5. I have a 98 expedition 5.4 L 2 v nip engine 4 x 4 that’s an extremely good shape. I want more horsepower for towing. I’m looking for low end horsepower and torque and thought these heads would be a good answer? Given the cost of a new SUV, dropping a couple thousand dollars and sweat equity might be a good investment in my truck. Suggestions?

    • I have the same question. Any benefit from these heads for towing applications? Perhaps in conjunction with a towing-appropriate cam?

  6. I have a 98 4.6L f150 it’s sohc 2v what’s the biggest cam I can stick in it with it being completely stock an no motor work done

  7. I have a 2002 mustang gt pretty much stock with only 60k miles on it. Have borla cat back, bbk pulleys, bbk throttle body and plenum and K&N CAI. Do you guys have a complete kit i can bolt on install that includes everything needed? Great read by the way.

  8. Roy saulnier says:

    What is the price for trick flow heads for a 2001 mustang gt? Also the the shipping to NS.

  9. Roy saulnier says:

    Price on cylinder heads for 4.6 2v. 2001 mustang

  10. Bryan G Sheffler says:

    Would be nice to see the difference between just the stock PI heads and the Trick Flow’s without a cam change and using the stock intake manifold. I can change the came in my stock PI, and get a 50 HP increase over the stock cam at 5,800 RPM and that is with a milder cam then Trick Flow uses. The 6,500 RPM stated for the power increase is really beyond the usable RPM range of most street motors. If you put in a bigger cam and spin it fast enough, it will produce more power over stock. I’ve asked Trick Flow for an answer to the Apples to Apples comparison on a stock motor with the stock cams, and only heard crickets from them.

  11. Gary crump says:

    Do you sell a top end package heads cams and intake for a 99 4.6 2v

  12. Allen Gorham says:

    I have a set of 38 cc heads and was wondering what the compression would be if I put them on a 96 cobra motor

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