Welcome to the second installment in our series on small-block Ford cylinder heads; a look at steel and aluminum castings that are designed for solid street and track performance. As many of you know, street/strip is the parlance that usually describes such pieces (especially for '79-present Mustang loyalists like us). However, since dragstrips aren't the only motorsports venues where late-model Ponies stampede, we begrudgingly acknowledge the fact that "track" is a more-appropriate term for the heads' performance purpose.
Street-specific castings for 5.0-liter/302 engines typically are CNC-ported, include larger valves and upgraded valvetrain hardware, and have improved flow capabilities over stock 5.0 (E7TE, for example) heads. The sampling of street cylinder heads we presented in Part 1 features true bolt-on pieces, that do not require exotic (and oftentimes expensive) supporting hardware or engine modifications, and in some cases, the heads are approved as legal for street use in all 50 states by the California Air Resources Board.
With the street-'Stang bases covered, it's now time to move onto a slightly bigger entity in the Mustang-performance food chain. Cylinder heads we're presenting in this report are geared more toward aggressive-yet-still-streetable 5.0/302 and 351W engine combinations, which usually are power-adder assisted (supercharged, turbocharged, or nitrous injected).
Heads designed for road-and-track-style Mustang engines generally feature larger, sometimes-raised, CNC-opened ports, big valves, and big combustion chambers, which give them the ability to flow much more air than stock heads, or most of the heads that are highlighted in our initial report. Although there are a few heads included in this report that crossover from the "street" category, the heads we're classifying here as street/strip (sorry, we couldn't hold it back any longer) have a lot more intricate nuances than their bolt-on-and-go counterparts, and they really help engines produce the type of big steam (600-plus rear-wheel horses) we really dig.
The heads featured here range in price from $1,200 to $2,500 per pair, and require significant internal and external engine mods (aftermarket pistons, camshafts, intake manifolds, headers, and so on). They typically work well with the higher-displacement, stroker engines such as the 331s, 347s, 393s, and 408s that power many of today's 1,000hp street Mustangs.
Yes, big-steam 'Stangs are a lot more common than they were when the late-model Pony craze took off more than 30 years ago, and as you'll learn through the following photos and captions, advancements made in cylinder-head design definitely are major reasons why this is so.
Air Flow Research
While it wasn't included in our rundown on street cylinder heads, AFR's 185cc street heads (PN 1420, 58cc chamber, stud mount; PN 1492; 60cc chamber, pedestal mount; PN1422, 72cc chamber,stud mount, $1,461) actually are 50-states-legal castings that we believe cross over into the road-and-track category. The 185s also are direct bolt-on heads that feature lightweight 8mm valves (2.02 intake; 1.60 exhaust), the same Manley retainers and lightweight, Pacaloy springs (1.29-inch OD) that offer a 50-grams-per-cylinder in weight reduction, which lessens the chances of experiencing valve float at high rpm. AFR 185s flow 277 cfm at 0.600-inch lift (intake), are great for nitrous or forced-induction applications, and make power from 1,500 rpm through the 6,000-rpm rev range.
We have a personal affinity for AFR's 205 cylinder heads (PN 1450, 58cc chamber, stud mount; PN 1458, 72cc chamber, stud mount, $1,842), as they're the castings that sit atop the A.R.E.-built small-block that powers our '86 T-top coupe project Mustang. The 205 heads are fully CNC-ported, feature lightweight 8mm valves measuring 2.08 (intake) and 1.600 (exhaust), and have the ability to move huge volumes of air (intake flow measures 310 cfm at 0.700-inch lift) that make big horsepower and torque numbers fairly simple to achieve, on muscle or with a power adder. The heads come with 1.550 OD Pacaloy roller springs, Manley retainers, bead locks, and ARP 7/16-inch studs. AFR recommends its 205 castings for 331-to-392 stroker engines. One important spec to note is that exhaust ports are raised 0.125-inch on the 205 heads, which is something to be mindful of when you're shopping for headers.
Dart's Iron Eagle cylinder heads (PN 13301182, 58cc chamber, 1.94-inch intake valve; PN 13301112, 58cc chamber, 2.02-inch intake valve; PN 13311182, 62cc chamber, 1.94-inch intake valve; PN 13311112, 62cc chamber, 2.02-inch intake valve-all with 1.437 double valvesprings, $1,311.60) are cast-iron pieces that get it done on streetable/raceable, hopped-up small-block Ford engines. The CNC-machined heads flow 247 cfm at 0.500-inch lift on the intake side, and 159-cfm exhaust, also at 0.500-inch lift, and feature intake-port volume measuring 180cc (73cc exhaust). Iron Eagles are set up for stud-mount rocker arms, and as we learned in our own dyno and dragstrip tests, with a compatible camshaft, intake manifold, and exhaust system can improve an otherwise stock 5.0's output to roughly 350 rwhp, and carry a Fox GT to 12-second e.t.'s in the quarter-mile.
|Cylinder Head Specifications|
|KC LH F 17 195||KC LH F 17 210|
|Valve Sizes Intake/Exhaust||2.020/1.600||2.080/1.600|
|Intake Manifold||Small-block Ford||Small-block Ford|
|Flow Chart CFM @ 28 Inches Of Water|
|KC LH F 17 195||2.020 Intake||154||219||260||287||294||296||300|
|(CNC Ported)||1.600 Exhaust||119||169||200||209||213||214||214|
|KC LH F 17 210||2.080 Intake||151||223||269||300||319||322||323|
|(CNC Ported)||1.600 Exhaust||113||166||200||217||222||222||222|
Edelbrock's Performer RPM XT (PN 51259 59cc chamber, 2.02-inch intake valve; PN 60359 60cc chamber, 2.02-inch intake valve; $1049.95/ea) are 302-, and 351W-stroker-friendly aluminum castings that are a unique hybrid of as-cast and partial CNC porting (only in critical areas). The combination was developed in an effort to make the heads more affordable than fully CNC'd pieces. Peak intake flow is 292 cfm at .600-inch lift (209 exhaust), and the heads have port volume that measures 185cc on the intake side (75cc exhaust). The stud (rocker arm)-mount units include 1.57-inch (exhaust) valves, beehive springs, an 18-degree valve angle, and has machining in the area below the deck that facilitates changing link-bar-style roller lifters without removing the heads.
Edelbrock's Victor Jr. heads (PN 77189, 60cc chamber, 2.05-inch intake valve, $762.87 each) are the big dogs in the company's road-and-track lineup for 5.0-powered 'Stangs. Victor Jrs. have port volume measuring 210cc on the intake side (75cc exhaust), and are stud (rocker arm) mount units that come assembled with 2.05-inch (intake), 1.60-inch (exhaust) valves, and 1.55-inch (OD) springs. With peak intake flow of 291 cfm at 0.600-inch lift and 195 cfm on the exhaust side, Edelbrock's Victor Jr. cylinder heads perform well through the 7,500-rpm range, and support well beyond 500 hp at the feet.
Ford Racing Performance Parts
Ford Racing's Z heads (PN M-6049-Z304DA, 63cc chamber, 2.02-inch intake valve, $1,695) are the next step in bolt-on performance castings for small-block Ford engines that see street and on-track racing duty. The heads feature a 20-degree valve angle, and flow approximately 277 cfm (intake) at 0.550-inch lift (218-cfm exhaust). The Z heads require 7/16-inch screw-in rocker studs, and they are fitted with 2.02-inch intake and 1.60-inch exhaust valves (with port volumes of 204 cc and 85 cc on the intake and exhaust sides, respectively). Since exhaust ports on FRPP's Z heads are raised, count on having a set of custom headers made to complete the upgrade.
Patriot Performance is recognized as a company that set a standard for affordable, bolt-on aluminum 5.0 cylinder heads, years ago. Today, Patriot's Freedom Series heads (PN 1102, 60cc chamber, 2.02-inch intake valve, $935) carry on that tradition of being a cost-efficient option over ported stock heads. The heads are cast with generous ports (185cc intake/72cc exhaust) that flow 260 cfm at 0.550-inch lift on the intake side, and are assembled with 2.02-inch intake/1.60-inch exhaust valves (five-angle valve job), hydraulic-roller springs, steel retainers, 3/8-inch (rocker-arm-mounting) studs, guide plates, and Viton seals.
Racing Head Service is the best-kept-secret (until now) entry in our review of small-block Ford heads. RHS offers its 20-degree, 180cc and 200cc Pro Action cylinder heads in cast-iron and aluminum (PN 35304-02/PN 35305-02-iron 180cc/200cc, 58cc chamber, 2.02-inch intake valve; PN 35301-02/PN 35302-02-iron 180cc/200cc, 64cc chamber, 2.02-inch intake valve $1,200.00; PN 35011-02/PN 35012-02-aluminum 180cc/200cc, 58cc chamber, 2.02-inch intake valve; PN 35015-02/PN 35016-02-aluminum 180cc/200cc, 64cc chamber, 2.02-inch intake valve, $1,434). The heads are available fully assembled with hydraulic-roller valvetrain hardware. RHS says 289-421ci engines are perfect for its Pro Action castings.
While Trick Flow offers a wide variety of its Twisted Wedge aluminum cylinder heads, we think this as-cast version of the popular CNC casting (PN TFS-51400015, 64cc chamber, 2.02-inch intake valve, $1,499.95) is a good addition to our lineup of road-and-track heads. The heads' intake and exhaust runners are patterned after the CNC-ported heads, which gives them similar flow characteristics-approximately 277 cfm (intake) at 0.600-inch lift (218 cfm exhaust)-right out of the box, without the time and increased cost associated with CNC porting. While the heads (naturally) are cast with Trick Flow's unique-shaped combustion chambers (valves moved over the center of the cylinder bores), they also feature 2.02-inch-intake/1.60-inch-exhaust valves, have 190cc intake-port volume and 66cc volume on the exhaust side, and are capable of producing more than 500 naturally aspirated horsepower-as is.
For a few dollars more, Trick Flow's Street/Strip CNC heads (PN TFS-51410010-C01, 64cc chamber, 2.02-inch intake valve; 185cc intake-runner volume, $950 each; PN 51410010-C02, 65cc chamber, 2.02-inch intake valve, 205cc intake-runner volume, $1,000 each) basically have the same characteristics as the Twisted Wedge Street heads included in our last report, plus additional enhancements, such as higher-rate valvesprings (135 pounds seat pressure at 1.780-inch installed height); 10-degree, machined-steel super locks; and manganese bronze guides to support camshafts of up to 0.600-inch lift. These heads are good for more than 600 all-muscle ponies, and don't require custom headers or other supporting hardware.
Trick Flow's original High Port aluminum cylinder heads are arguably the castings that helped kick off the high-performance, small-block Ford head revolution. And, as a testament to how good the OG heads really are, you can still find vintage High Port Street/Strip heads on some of the fastest Fords around. Today's High Ports (PN TFS-51700001, 64cc chamber, 2.02-inch intake valve, $1,399.95) still have the same patented valve spacing, interlocking ductile-iron valve seats and thick decks as the originals, as well as excellent cooling characteristics. Most importantly, High Ports flow! Entry into each 192cc intake port has been reshaped to help seal the area along the port roof, and the 87cc exhaust ports are raised .750-inch over a stock head's port floor, to increased the exit flow of spent gasses (custom headers are required for High Ports).