Andrew Cluck
December 1, 2004
Photos By: Lindsey Druien , Al Papitto

Horse Sense:
While most Four-Valve modular owners are familiar with both B and C DOHC heads, few have even heard of the requisite A head that preceded them both. The first DOHC heads designed by Ford featured a dual-intake-runner/single-injector setup similar to the second-generation B heads. But since the As never made it to production, we're left with nothing but speculation concerning their performance capabilities. In this case, B is for "Better."

When broken down into its most basic elements, the explanation of why four valves are better than two seems extremely simple. As an engine is essentially a large air pump, it follows that the greater valve area (or potential flow area) inherent in an optimized Four-Valve head design will ultimately allow for more airflow (at all lift levels) than a similarly designed and optimized Two-Valve casting. Though basic dual-overhead-camshaft, four-valve-per-cylinder-head architecture has been around for more than 75 years, domestic manufacturers were slow to adopt the less conventional valvetrain design in anything but small-displacement, four-cylinder econoboxes until the early '90s.

Chevrolet's (Lotus-designed and Mercury Marine-built) 5.7L four-cam LT5 ZR-1 motor gets credit for being the first domestic production application of Four-Valve technology on an eight-cylinder engine (1990). But, it was Ford's modular Four-Valve designs that truly paved the way for those carrying the domestic overhead-cam performance banner in the mid and later parts of the decade. During the last 11 years, Ford has designed and produced no less than six different production modular (4.6 or 5.4 compatible) Four-Valve heads, and five of those have come in the last 5 years.

As anyone attempting a Four-Valve swap into a late-model GT, or those with '96-'01 snakes wanting to upgrade to newer Four-Valve heads will contest, modular DOHC head selection can be a scary thing. After all, as previously stated, there are six different production head castings from which to choose (five if you don't want to count the thousand or so '00 Cobra R heads cast), spanning from a production run that dates back to the '93 Lincoln Mark VIII. Just about any well-versed modular fan can tell you that there are zero aftermarket head offerings-other than those of Ford's own in-house speed shop, Ford Racing Performance Parts-available for modular connoisseurs today. Dual-overhead-cam modular owners shouldn't fret, as the silver lining to this otherwise dark cloud is the fact that aftermarket heads are not required. Ford's original-equipment Four-Valve heads have been used successfully on everything from its silky-smooth, luxury SUV line to 114-octane-swilling, six-second drag racers.

In order to assemble the most comprehensive and accurate Ford Four-Valve head information available, we enlisted the help of several premier modular engine builders. Racer/builder Al Papitto of Vero Beach, Florida, is the owner of Boss330racing.com and an '00 Cobra R-based, naturally aspirated, 5.4 '97 Cobra that is perilously close to the nine-second zone at a portly 3,400 pounds! Al cut his teeth in the ranks of Pro Stock motorcycle and Alcohol Funny Car racing, and has only recently begun to share his extensive overhead-cam engine-building experience with the Mustang community.

Likewise, James Hensler, owner of Hensler Racing in Reynoldsburg, Ohio, has been nothing short of a pioneer in the field of nitrous-assisted Ford Four-Valve racing. James is the pilot of a Nitrous Express-fortified, big-bore-modular- powered NMRA Renegade car. Look for him to eclipse last season's previous best of 9.30 at 150 by a large margin this year, with his Fox Lake-ported B heads/HCI intake top end finding a new home atop a 305ci big-bore short-block.

For more than two years, John and Mike Tymensky of Modular Performance in Novi, Michigan, have held the title of owning the quickest and fastest (9.34 seconds at 145 mph) naturally aspirated modular vehicle in existence. Project X, their yellow, FR500-headed, 305ci assault on the tarmac, is also packing some significant upgrades for the '04 season-a 5.4, a carb, an automatic transmission, and a distributor-style ignition among them.

While the experts above utilize dif-ferent Four-Valve heads on their respective cars, they all agree on one thing: There really are no bad choices for any application. Even the so-called "worst" of the bunch can still make serious power when used correctly.

With everything from basic dimensional information and intake selection help, to a complete Ford Four-Valve head flow-bench shootout, and expert advice from some of the most recognized names in modular racing, we're finally bringing you the definitive Ford DOHC head answers you've always longed for. So pull up a chair and decide once and for all which Ford Four-Valve head is best for your application.

B/Swirl Port
Available on '93-'97 Lincoln Mark VIIIs, pre-'99 Lincoln Continentals, and '96-'98 Cobras, these swirl-port castings were the first and only production Ford heads with two (square primary, round secondary) intake ports per cylinder, arriving first in the '93 Lincoln Mark VIII. They were aptly named, due to the way they promoted the incoming air to swirl into the combustion chambers, similar to water running down the drain of a once-full sink.

Through the years, these heads have proven themselves to be excellent performers at 8,000 rpm or more-mainly in power-adder applications-since their tremendous combined intake port cross-sectional area and volume (when combined, a full 55 cc more than any other 4.6 head design) provide exceptional power production in the upper regions of the tach. Ironically, it's those same big, beautiful, twin ports that also prove to be the B head's largest inherent design flaw. The extra intake port size has a tendency to kill low- to midrange-rpm intake port velocity and power production-hence the use of Ford's first Intake Manifold Runner Controls on '96-'98 Cobras. By allowing air to reach only one of a B head's twin intake valves, velocity, and therefore low to midrange torque, production was restored in situations less than 3,250 rpm. Later head designs are clearly superior in this regard, which is an important consideration for those wanting a stout street motor.

There is also some controversy over the single-fuel-injector/dual-intake-port setup. Some claim insufficient air/fuel mixing because of the compromised design. But others contest that the ability to make 1,000-plus rear-wheel horsepower with only minor porting and some form of power adder is testament to the contrary. Whomever you believe, there is little doubt that even after as few as 8,000 miles, carbon and other deposits tend to form on the secondary ports, causing a major airflow impedance, as there is no fuel present to clean them. B heads feature a somewhat small stock exhaust port that really hinders flow in power-adder applications. Major gains from porting come with a quality valve job, some pocket, and lots of exhaust work. There isn't a lot of material to remove from the intake ports themselves.

B heads aren't the best choice for a naturally aspirated street motor. In order to really shine, they need to be paired with a power adder and a short-block that can sustain high horsepower and rpm levels. These, the oldest heads, may still be a great choice for race applications.

Stock Intake Choices: '93-'97 Lincoln Mark VIII, '96-'98 Cobra
Aftermarket/Modified Stock Intake Choices: HCI, SSR, PHP
B Head Dimensions: Combustion chamber: 52 cc; Intake port volume: 107 cc primary (square), 115 cc secondary (round); Intake port entrance: 1.500x1.300-in primary (square), 1.660x1.400-in secondary (round); Valves: 37 mm int, 30 mm exh

C/Tumble Port
These second-generation Ford DOHC heads, found on '99-'01 Cobras and '99 Lincoln Continentals, feature a single intake port per cylinder, with a smaller cross-sectional area that boosts incoming airflow velocity compared to previous years. To understand how C heads earn their tumble-port designation, try to imagine an Olympic high diver doing repetitive front somersaults before cleanly entering a pool. This controlled tumble allows for bet-ter air/fuel mixing than in the earlier swirl-port heads. The new port design also produces both substan-tial increases in midrange torque and superior horsepower production below 8,000 rpm when compared with earlier heads. Combustion chamber size is also up 2 cc.

A design downfall of C heads, and their larger (5.4 Navigator) cousins, is the relatively flat floor and utter lack of a short-turn radius in the throat of the intake port. As such, the incoming air tends to overshoot the valves, making the port "think" the valves are smaller than they actually are. Some '99-'01 Cobra owners reported a "ticking/pinging" noise coming from the driver-side head of their cars. This was due to insufficient cooling around the number 6, 7, and 8 cylinders that allowed the valves to overheat and therefore seat improperly. Ford remedied the situation by issuing a TSB to remove and replace the affected heads with a version that featured altered coolant flow.

These heads feature a small exhaust port that resembles Ford's earlier swirl-port heads, but unlike in B heads, both the intake (throat region) and exhaust ports can see extensive porting work. But removing too much material from the intake port (mouth region) of a tumble port head will kill velocity quickly, so make sure your head porter knows what he is doing!

C heads remain a viable performance upgrade for those seeking more punch in their street-driven, Four-Valve 4.6, without having to pay new-part prices for the '03 DOHC or FR500 versions. The increased midrange torque pro-duction and greater overall area under the power curve (when compared to swirl-port heads) will enhance the performance of a street/strip modular regardless of application.


Stock Intake Choices: '99 and '01 Cobra, '03-'04 Mach 1 and Aviator, '03 Marauder, FR500
Aftermarket/Modified Stock Intake Choices: Al Papitto short runner/ported '99 and '01 Cobra, Hensler Racing ported stock runner '99 and '01 Cobra, MP carb intake
C Head Dimensions: Combustion chamber: 54 cc; Intake port volume: 177 cc; Intake port entrance: 1.960x1.350 in; Valves: 37 mm int, 30 mm exh

'98-up Lincoln Navigator
These 5.4L DOHC heads feature essentially the same intake port design as C heads, but they have a much larger intake port volume than 4.6 castings. Despite the fact that these heads feature a relatively small exhaust port, the extra intake port volume could be beneficial in helping fill a motor of greater displacement-think 5.4 liters. Expect slightly better midrange torque than even C heads, and sub-8,000-rpm horsepower production, although the larger intake port size leaves a slim selection of intakes to choose from when utilized on a 4.6 block. Forced induction fans take note-Navigator exhaust ports feature a thicker exhaust divider (while keeping the same overall exhaust port size as B, C, and FR500 heads) that allows coolant to circulate through this vital area. Conversely, the larger divider can also hurt flow by utilizing additional space in the port.

The real downside to Navigator heads, when used on a 4.6-based engine, is the severe limitation they impose on intake selection. The physically larger 5.4 heads don't leave a lot of room (when installed on a 4.6 block) between them for an intake plenum to sit-though they do bolt right up. Remember that since Navigator intake ports are essentially clones of those of C heads (just on a larger scale), they too suffer from the same intake port flaws that plague the earlier tumble-port design-no short-turn or floor in the throat of the intake port.

The extra port volume the Navi heads possess could be beneficial in filling a motor with greater than 281 ci of displacement, or in high-rpm naturally aspirated or supercharged street/ strip combinations. Fans of boost should remember the cooled exhaust port divider. Lack of intake availability is the real downfall of this otherwise wonderful casting.

Stock Intake Choices: None (4.6), '98-up Navigator (5.4)
Aftermarket/Modified Stock
Intake Choices: Al Papitto short-runner '99 Cobra (4.6), sheetmetal
Navigator Head Dimensions: Combustion chamber: 53 cc; Intake port vol: 184 cc; Intake port entrance: 2.290x1.400 in; Valves: 37 mm int, 30 mm exh

'00 Cobra R
Cobra R heads are the best modular heads available today. But their extremely scarce supply makes them both ridiculously hard to find and unbelievably expensive.

Initial performance results are understandably hard to obtain, but Al Papitto reports that with only 25 hours of port work into his new '00 R heads, they have already eclipsed the performance of his old Navigator heads with months of labor in them. These heads feature larger intake and exhaust ports, 2mm-larger exhaust valves, and a dry exhaust port divider that flows nearly as well as a stock 4.6 C head intake port. Cobra R heads also require the use of a specific valvetrain not shared with any other modular application due mainly to their physically larger size-because of the raised (taller/longer) intake port. Al also claims R heads have too much port volume for a street/strip 4.6 application; consider them only with a larger 5.4 motor or a serious 4.6 race application paired with some form of power adder.

These are simply the best heads you can (or can't) find for a modular motor. You are as likely to come across a set of these modular "Godfather" heads as you are to be Britney Spears' next ex-husband. Though based on their performance abilities, you may want to start saving, just in case.

Stock Intake Choices: None (4.6), '00 Cobra R (5.4) Aftermarket/Modified Stock
Intake Choices: Sheetmetal
'00 Cobra R Head Dimensions: Combustion chamber: N/A; Intake port vol: N/A; Intake port entrance: 2.370x1.300 in; Valves: 37 mm int, 32 mm exh

FRPP FR500
The sole "aftermarket" offering of the bunch, these high-flow heads feature a modified C-head intake port combined with the smallest port volume of the group-it seems Ford meant to design these heads for high-performance, naturally aspirated applications. With the same small standard exhaust port as most other DOHC heads, you will still have to remove a decent amount of material from the exhaust ports for power-adder apps.

Port entrance shape/size remains identical to C heads, so finding an intake isn't difficult. These heads are capable of producing power beyond 8,000 rpm, where earlier versions of the tumble-port castings begin to lose their luster. FR500 heads are prone to the number 6, 7, and 8 cylinder cooling problems as well. Major intake port differences between these and earlier tumble-port heads include a raised intake port roof and a real short-turn radius that better directs the incoming air into the combustion chamber-not over the valves as in earlier versions of tumble-port heads. These heads also feature a dry divider in the exhaust port, which allows for greater flow but also higher temperatures. Though improved, the heads can still use some TLC from a quality porter to smooth the roughly finished and newly implemented short-turn radius, and the standard exhaust treatment.

FRPP's offerings are outstanding performance heads, with exceptional low- and mid-lift flow capability. The FR500's only real fault is that the newer '03 DOHC heads provide nearly iden-tical performance capability for less money. Still, these offer a great choice for any application as the heads readily pair to a wide variety of stock and aftermarket intakes.

Stock Intake Choices: '99 and '01 Cobra, '03-'04 Mach 1 and Aviator, '03 Marauder, FR500 Aftermarket/Modified Stock
Intake Choices: Al Papitto short runner/ ported '99-'01 Cobra, Hensler Racing ported stock runner '99-'01 Cobra, Modular Performance carb intake
FR500 Head Dimensions: Combustion chamber: 53cc; Intake port vol: 160 cc; Intake port entrance: 1.960x1.350 in; Valves: 37 mm int, 30 mm exh

'03 DOHC Head
Widely used on the '03-and-newer Lincoln Aviator, Marauder, Cobra, Mach 1, and Australian Boss 260/290, these heads are state-of-the-art in street modular heads. Featuring nearly iden-tical intake ports (though 17 cc larger in volume due to the fact that they are also used on the much larger Australian Boss 260/290 5.4L DOHCs) to the FR500 heads, but combined with a newly designed, larger, and more rectangular exhaust port, these may be the best all-around readily available DOHC Ford heads ever manufactured. The improvements made to the intake port shape in previous years include a raised port roof and the introduction of a short-turn radius in the throat of the intake port that helps assure the incoming air charge finds the combustion chamber.

For those with a forced-induction street/strip motor, these are without question the best heads available, and as with the FR500s, they should produce great power up to and beyond 8,000 rpm regardless of application. These heads also feature higher-quality head castings from the supplier, which is at least partially responsible for the modest increase in flow versus the earlier castings-chalk that up to Ford's revised quality control standards.

Early runs of the '03 DOHC head fell victim to the same number 6, 7, and 8 cylinder coolant flow problems as earlier tumble-port castings. In mid-2003, Ford made a running revision to the '03 DOHC heads that allowed more coolant to circulate through the affected areas. A blue mark on the driver-side head indicates an updated casting, and there are no additional revisions to the '04 version of this design.

By all accounts, these are the best all-around modular Four-Valve heads currently available. They combine the exceptional flow of a slightly larger FR500 intake port with a gigantic, new rectangular exhaust port.


Stock Intake Choices: '99 and '01 Cobra, '03-'04 Mach 1 and Aviator, '03 Marauder, FR500 Aftermarket/Modified Stock
Intake Choices: Al Papitto short runner/ ported '99-'01 Cobra, Hensler Racing ported stock runner '99-'01 Cobra, Modular Performance carb intake
'03 DOHC Head Dimensions: Combustion chamber: 52 cc; Intake port vol: 177 cc; Intake port entrance: 1.960x1.350 in; Valves: 37 mm int, 30 mm exh

Our panel of experts surmised that, aside from the nearly unobtainable '00 R heads, the '03 DOHC heads are without question the right choice for your modular Four-Valve performance application. The combination of a slightly larger FR500 intake port and modified throat region, combined with a new, larger rectangular exhaust port and a relatively low price (due to its widespread use in the Ford organization), makes the '03 DOHC casting the current stud of Ford's modular stable.

After porting, the relatively small stock valves become the most serious flow limitation. As such, aftermarket replacements should be a considera-tion for those looking to squeeze every last drop of performance from their DOHC heads.

On the Bench
Unported Head Flow Data (flowed at 28 in of H2O)
  B Head Int. B Head Exh. Navi Int. Navi Exh. FR500 Int. FR500 Exh.
w/Exhaust
Flowtube
'03 DOHC
Int.
'03 DOHC
Exh.
C Head Int. C Head Exh.
0.100 in 92 cfm 67 cfm 91 cfm 69 cfm 90 cfm 60 cfm 95 cfm 74 cfm 87 cfm 68 cfm
0.200 in 153 cfm 123 cfm 157 cfm 122 cfm 168 cfm 129 cfm 161 cfm 126 cfm 153 cfm 121 cfm
0.300 in 214 cfm 143 cfm 212 cfm 145 cfm 240 cfm 170 cfm 226 cfm 159 cfm 204 cfm 145 cfm
0.400 in 230 cfm 154 cfm 238 cfm 154 cfm 283 cfm 186 cfm 259 cfm 171 cfm 223 cfm 153 cfm
0.500 in 259 cfm 161 cfm 257 cfm 163 cfm 291 cfm 192 cfm 266 cfm 175 cfm 231 cfm 159 cfm
0.550 in n/a n/a n/a n/a n/a n/a 268 cfm 176 cfm 231 cfm 159 cfm
0.600 in n/a n/a n/a n/a 301 cfm 195 cfm n/a n/a n/a n/a

Ported Head Flow Data (flowed at 28 in of H2O)
  Fox Lake
B Head Int.
Fox Lake
B Head Exh.
Fox Lake
Navi HeadInt.
Fox Lake
Navi HeadExh.
Houston
Perform.
FR500 Int.
Houston
Perform.
FR500 Exh.
Houston
Perform.
'03 DOHCInt.
Houston
Perform.
'03 DOHCExh.
C Head Int. C Head Exh.
0.100 in 99 cfm 89 cfm 94 cfm 88 cfm 95 cfm 63 cfm 98 cfm 68 cfm 91 cfm 70 cfm
0.200 in 177 cfm 154 cfm 183 cfm 158 cfm 175 cfm 137 cfm 189 cfm 140 cfm 184 cfm 154 cfm
0.300 in 248 cfm 202 cfm 247 cfm 204 cfm 251 cfm 181 cfm 266 cfm 189 cfm 248 cfm 182 cfm
0.400 in 284 cfm 221 cfm 279 cfm 225 cfm 306 cfm 205 cfm 315 cfm 214 cfm 277 cfm 197 cfm
0.500 in 311 cfm 233 cfm 304 cfm 236 cfm 330 cfm 219 cfm 331 cfm 229 cfm 290 cfm 208 cfm
0.550 in n/a n/a 311 cfm 238 cfm n/a n/a n/a n/a n/a n/a
0.600 in 323 cfm 238 cfm 314 cfm 242 cfm 340 cfm 226 cfm 342 cfm 237 cfm n/a n/a

The flow bench results seemed to strongly reiterate what the experts had already stated. The Houston Performance-ported '03 DOHC heads come out on top of the flow war (not counting the ultra-rare '00 R heads) by a slim margin-mainly in exhaust flow-over the also Houston Performance-ported FRPP FR500 castings. Compared to a similarly prepped '99-'01 C head, flow is up across the board, with large disparities, in favor of the two newer heads, coming at both low and high lift.

Fox Lake's worked B heads flowed nearly as much as the newest tumble-port heads, relying mainly on sheer volume, as opposed to velocity as in the newer single-intake-runner tumble port castings, to get the job done. Not too shabby for a decade-old design. Coming in a close fourth on the bench, Fox Lake's ported Navigator heads provide for slightly more intake flow than a regular C head-due mainly to the larger intake port volume of the 5.4 head.

It should be noted that any set of Four-Valve heads can be ported to flow "X" amount of air, given enough time and labor. For example, a set of '99 and '01 C heads can ultimately be made to outflow a ported set of FR500 heads if enough extra time and/or money is invested in them. But, with an equal investment in both heads, the FRPP offerings would once again come out on top. Therefore, it may be more cost effective for those with already ported DOHC heads to invest the additional time and money into improving their existing units, rather than upgrading to a newer casting and starting over.