The three-tiered approach to building an LS killer included inches, a top-end kit and a little juice.

Words and Photos By: Richard Holdener

Everyone knows the GM LS family gets all the love, but what about the Ford guys? Fast Fords have been a time-honored, blue-oval tradition, dating back to the Flathead. With everyone hot on swapping LS motors into everything with wheels, where does that leave a true believer? Suppose you want a powerful combination for your classic, or even 5.0L, Mustang (or any fast Ford). The first thing you do is pass on building a 5.0L. I know, the injected 302 all but resurrected Ford performance — and we love them for it — but the late-model 5.0L block was not nearly strong enough to withstand the power level we had in mind.

Even in 347 stroker guise, the hydraulic-roller 5.0L block just doesn’t have sufficient strength to handle the power loads, especially once we add the nitrous. Stepping up from the 5.0L, we decided the build would revolve around the larger 351W. The Windsor added both strength and capacity, as the 351W could safely be taken out to 408 cubic inches.

Having decided on the main component, it was time to fill all the holes. The additional 57 cubic inches came courtesy of Speedmaster and Mahle. Speedmaster supplied the 4.0-inch stroker crank (up from the stock 3.50 inches) and 6.20-inch rods. These were combined with .030-over Mahle forged (dished) pistons to produce the finished displacement of 408c.i. Adding an extra 57 cubic inches immediately adds power and torque compared to a stock 351W, but naturally we wanted even more.

To get more, the 408 stroker bottom end was combined with a trio of top-end components from Trick Flow Specialties. The combo included a TrackMax cam, single-plane intake, and a pair of 205cc Twisted Wedge 11R heads. This top-end kit was designed to work together to optimize power production. The TrackMax cam offered .595 lift (both intake and exhaust), a 250/254-degree duration split (@.050), and a 110-degree lsa. The TFS TW 11R heads check in with 205cc intake ports that flowed 321 cfm, 66cc combustion chambers (also available in 56cc), and a spring package designed for the sub-.600 lift cam. Rounding out the package was the ready-to-rev, single-plane intake.

With the short block and power producers accounted for, it was time for the rest of the gang to join the party. Sealing the heads to the short block was a set of Fel Pro MLS head gaskets and half-inch ARP head studs. Down below, the oiling system consisted of a standard volume oil pump, an ARP drive shaft, and a complete Milodon pan, pick up, and windage tray. Pans and windage trays are one of those often missed areas that yield extra power, to say nothing of providing a rock-steady oil pressure curve. Tucked under the cast-aluminum, TFS valve covers was a set of 1.6-ratio, Ultra-Gold roller rockers and hardened pushrods from COMP Cams. Also present was an SFI-approved damper from Speedmaster, an MSD ignition that included a billet distributor and 6AL ignition amplifier, and a Meziere electric water pump.

After a couple of break-in cycles on the dyno, the 408 showed us just how fast a Ford can be by posting peak numbers of 603 hp and 532 lb-ft of torque. Torque production from the stroker exceeded 500 lb-ft all the way out past 6,200 rpm.

Now, you might think we would be satisfied with our 600-hp 408, but you’d be wrong. When we started this adventure, we wanted more than just a fast Ford, we wanted a FAST FORD (yep, that’s right-all caps). Knowing what was waiting out there on the mean streets, we decided to add a little insurance to the program in the form of a Zex nitrous kit.

The Zex Perimeter Plate nitrous kit offered a number of beneficial features, including Perimeter Injection, Cryo-Sync, and Airflow Enhancement Technology. Designed to equalize cylinder-to-cylinder distribution, the Zex carbureted plate system employed 12 (equidistant) injection points that flowed both nitrous and fuel evenly into the manifold. The injection of super-cool nitrous (at -127 degrees) through the plate (sandwiched between the carb and intake) effectively turned it into a Cryo-Sync (or heat isolator) cooling both the intake and carburetor. In addition, the high-pressure flow of nitrous and fuel through the spacer plate and into the manifold also worked to create a low-pressure zone to further enhance airflow into the motor.

On paper, the Perimeter Plate system sounded plenty impressive, but would these benefits translate into real power? To find out, we installed the Perimeter Plate between the Holley 950 XP carburetor and the single-plane, TFS intake for testing. Available with jetting to adjust the power output, we selected an extra 175 hp for the 408. After warming the bottle, purging the system, and testing the fuel flow rate to the plate, we finally got to run the Zex in anger.

What else can we say but WOW, as the nitrous system improved the power output of the 408 Ford from 603 hp and 532 lb-ft of torque to 788 hp and 693 lb-ft. To keep things safe, we purposely activated the nitrous late in the rev range, but you will likely experience even greater torque gains with earlier activation (just don’t get greedy). It is amazing how much power the Zex kit added and how easy it was to use. No wonder nitrous is so popular, especially for guys looking to be First On Race Day!

Sources: ARP, Arp-bolts.com; COMP Cams; compcams.com; Holley/Hooker/NOS; holley.com; JE Pistons; jepistons.com; Mahle Motorsports; Us.mahle.com; Milodon, Milodon.com; MSD, Msdignition.com; Speedmaster, Speedmaster79.com; Trick Flow Specialties, trickflow.com; Zex, www.zex.com.