The 5.0 Mustang & Super Fords Archives
March 1, 2001
Contributers: The 5.0 Mustang & Super Fords Archives

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138_90z Ford_mustang_lx Left_front_view
Many of the quickest 4.6 engines have been raced in the Fox chassis, such as John Mihovetz’s LX.
FRPP aluminum cylinder heads feature larger-than-stock stain- less valves, relocated intake valve centerlines, and airflow increases of 27 percent (intake) and 44 percent (exhaust) over the stock ’96-’98 castings.
Street-oriented Vortech kits now receive the new V-2SQ blower featuring quiet-operating helical gears, while those with more serious intentions can receive the straight-cut T-Trim. Scrolling back to a ’96 S-Trim bolt-on at Steeda, we noted a 96hp and a 69 lb-ft torque increase on a nearly stock ’96 GT (underdrives, mufflers, and K&N filter). The resulting 296 rear-wheel horsepower is at least 30 more than a stock Cobra of the era. Vortech’s Bob Roesé mentioned the V-2SQ has an improved step-up ratio, providing better boost at low rpm, as compared to the V-1 S-Trim.
Nitrous Oxide Systems builds this dedicated kit to fit both Two- and Four-Valve modulars. Part number 5171 is a dry system and can be jetted to make between 50 and 125 hp on the Two-Valve engine. The complete kit includes a dedicated wiring harness with factory-style connectors, along with an inline auxiliary fuel pump, and is priced at $973.
138_94z Ford_mustang Engine_bay
As for removing the 4.6, early reports indicated dropping it out the bottom was the way to go. While some well-equipped shops still seem to favor this technique, pulling the engine out the top is just another straightforward job (check out our how-to “Pop Goes the Motor” on p. 44 of the Jan. ’99 issue).
138_95z Ford_mustang Engine_view
As if making significant horsepower wasn’t enough, the FRPP intake is nice from a cosmetic standpoint too—a vast improvement over the horse-adorned composite stocker.
138_96z 1996_ford_mustang_gt Right_rear_view
Longtime readers will be no stranger to Steeda’s rolling Two-Valve testbed. The fully loaded ’96 GT is currently knocking down 11.40s at 122 mph thanks to 530 rear-wheel horsepower. FRPP heads, intake, and a T-Trim Vortech making 16 pounds of boost are the big players here. Extensive R&D has helped determine the necessary components that keep such an engine together for the long run.
Sean Hyland long-tube headers use a stepped design, which strives to combine the low-rpm torque of a small-tube header with the top-end power associated with big tubes. Two versions are available—one with 1-5/8 to 1-7/8–inch diameters, the other with gigantic 1-7/8 to 2–inch pipes.
Sean Hyland billet Two-Valve sticks will really make themselves known between 4,000 and 6,500 rpm, so consider deep gears as mandatory companions to a stick-shift tranny.
Here’s a shot of Speed-Pro’s excellent stand-alone engine-management system. This setup got the nod from hard-running Two-Valve racer Joe Charles, who chose it as much for the ease of making his modular-in-a-Fox swap as for Speed-Pro’s aggressive tuning capabilities.
Just like a 5.0 liter, the Two-Valve seems to favor more timing than the factory provides. Instead of a twist at the distributor, the modular needs this trick timing adjuster from Steeda—it works on Four-Valve engines as well.

More than ever, we find our mailbag stuffed with questions regarding performance upgrades for the anemic '96-'98 4.6 Two-Valve engine. Ford helped close the gap between enthusiast expectations and product reality with the introduction of the 260-horse '99s, but many readers seem to be wondering what it takes to turn the earlier Two-Valves into legitimate contenders. With warranties expiring on the '96-'98s and used car prices becoming more affordable, it's a valid question. While we've touched on various ways of pumping up this engine in the past, it seems appropriate to pull it all together and examine the current options.

As we reviewed dyno numbers from previous bolt-on tests and spoke with enthusiasts who are actively building 4.6 power, it's clear the modular Two-Valve responds well to modification. The options certainly aren't as varied as with a 5.0, but if you've ever been stymied by the myriad of heads, intakes, and such for our favorite little small-block, that's not an entirely bad thing.

It seems the street crowd is most interested in waking up this disrespected 4.6, though we're beginning to see considerable action on the drag-racing front as well. The advent of mod-motor classes are helping to broaden interest in Two- and Four-Valve modulars, as evidenced by the 2000 Fun Ford Weekend opener at Bradenton--it hosted a field of 66 cars in the class. So whether you're craving 10-second strip slips, looking to show your taillights to a cocky LS1 Camaro, or simply wanting to increase the fun factor on your daily driver, here's a look at the parts and pieces that can make it happen.

Cylinder Heads
While it would be nice to say there's hope for the original castings that came bolted to the '96-'98 engines, it just isn't in the cards. The problem with the stockers seems to be particularly miserable exhaust-flow numbers, which while possible to overcome with serious work, have not proven cost effective.

Stepping up to the FRPP heads is the most obvious option at this point, with chassis dyno numbers showing a solid 30hp gain all by themselves.

If you're not content to use these pieces right out of the box, remember we treated a set to the Extrude Hone process last year ("More Flow Through Putty," Sept. '99, p. 75). Extrude Hone squeezed out flow improvements of 12 percent on the intake side and 8 percent on the exhaust. As for more traditional porting methods, Sean Hyland Motorsport has found good results by paying particular attention to the short-side radius and seat areas, which, combined with a bit more finish work, can unleash another 10-12 horses.

Falling somewhere between the lowly early heads and the FRPPs are the factory '99-2000 castings. FRPP's Andy Schwartz describes them as "a good step up" from the originals, though there aren't any plans to offer them through the FRPP catalog. However, Parkway Ford's Joe Charles alerted us to the fact that fully assembled '99-2000s are currently terrific bargains at your local Ford parts counter. We called several Ford dealers near us and found the pricing is no fluke--try $355 each (including the cam!), though Joe figures Parkway can do even better.

The '96-'98 valve covers and intake won't work with the '99-and-up heads, so you'll have to spring for the compatible '99-2000 hardware, but it's still an option worth strong consideration. And, don't forget the possibilities that might exist in your local wrecking yard. We need to point out that the FRPP intake isn't advertised to fit the '99-2000 heads, but Joe tells us a port match and bit of welding around the water passages had him up and running with no other problems. We also suspect FRPP will have an updated intake for the later heads in the not-too-distant future.

Steeda's Nick Spinelli provided some revealing flow numbers we've listed in the attached chart (see the Flow Numbers sidebar. He mentioned Steeda would like to offer a CNC-ported '99 head/cam combo in the future. Let's stress the "would-like" portion of that statement, as the company is still determining the logistics of such a possibility. Suffice to say that if it happens, you'll be reading about it in 5.0 Mustang & Super Fords.

Intake Manifolds
While rumor has it more intakes are on the way, let's focus on the only available offering for normally aspirated--PN M-9444-D46 from FRPP. This is a complete kit whose main components include a three-piece aluminum intake, a Cobra dual-bore throttle body, and a revised strut tower brace. When combined with FRPP heads and headers, the FRPP heads produced a total increase of nearly 70 rear-wheel horsepower--a number that's just as good, if not better, than what's typically seen with similar, street-oriented 5.0 mods!

Andy points out these components have been designed to equal torque output of the stock components in the lower rpm range, while posting big gains as the revs rise.

Those of you who don't have the money for a complete intake upgrade could see a small improvement from a larger throttle body. It won't fit the FRPP intake if you decide to go that route later, but you'll probably see a few extra horses for less than $200. That said, we've seen more significant improvements from items such as a K&N filter, a larger air meter, under-drive pulleys, and exhaust components, so we'd go that route first on a simple bolt-on effort.

The available short-tube headers offer a generally accepted 7-10hp boost, but they are just a spoke in the wheel of a complete, high-flow exhaust system. Just as in 5.0 applications, the addition of high-flow cats and an after-cat system will be good for a few more ponies, not to mention a more commanding sound. For more serious intentions, long-tube headers are available from at least a couple of sources, including SHM. Sean Hyland believes these pipes to be worth 25-30 hp on a full-boogie deep breather, but he is the first to point out you'll never see these numbers on a nearly stock engine.

Certainly it's a double whammy when it comes to changing camshafts for the Two-Valve 4.6. Not only are two cams more complicated and time consuming to install than a more traditional V-8's single stick, but there's also the additional expense. The latter is a big reason we haven't seen cams offered through FRPP. As Andy Schwartz explained, they've yet to find enough extra power to justify the cost.

Keep in mind that FRPP's emphasis on excellent street manners is no doubt a contributing factor, but if you're willing to sacrifice some driveability for a stronger top-end charge, SHM can oblige. The company actually offers a couple of different grinds depending on your intent. First up are the billet sticks aimed at manual-trans applications, which Sean describes as "quite lumpy." Now we're talking! Featuring 0.495-inch lift and 230 degrees duration at 0.050, this setup claims about 30 extra horses when combined with FRPP heads, intake, and exhaust upgrades, though the cams aren't emissions legal.

Those running a slushbox would be better off with SHM's other duet, which are similar to the '99-2000 cams. They offer emissions compliance and better pricing since they aren't made of billet material, and they pick up about 8 hp.

The ever-expanding world of electronic trickery is definitely available for the modular Two-Valve--ranging from computer chips and high-flow mass air meters to stand-alone programmable engine management. The latter includes a new Holley system, a Speed-Pro, and the high-brow MoTeC. We suggest you make the acquaintance of a qualified modular tuner if you're considering some of this serious hardware/software.

Power Adders
You knew we were going to end up here, didn't you? When considering the added cost and difficulty of installing power building heads and cams on the 4.6, big-time gains via force feeding appear better than ever. Perhaps this is why there's a wider variety of supercharging options than any other component in the Two-Valve arsenal. Nearly all the name blower manufacturers are up to speed on this application, along with a couple of names you might not normally associate with superchargers--Saleen and Allen Engine Development.

If it was tough for the supercharger manufacturers to package their wares in a full-to-the-brim modular engine compartment, it has to be even more so for those developing turbo systems. At this point, we know Incon Systems is looking at the modular engines. We hope others will join the fray soon.

While turbos are more difficult to package, nitrous oxide is quite adaptable and wins the biggest-bang-for-the-buck award on the Two-Valve modulars. Of course we all know the pitfalls of nitrous--it's only there when you turn on the switch, bottles need refilling, it isn't well suited to road racing/open track activities, and so on. Nevertheless, when it comes to 100hp boosts for less than a grand, nothing else can compete.