Steve Turner
Former Editor, 5.0 Mustang & Super Fords
February 1, 2000
Photos By: Rob Kinnan, Chuck James

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138_13z Ford_mustang_gt Right_rear_view138_14z Ford_mustang_gt Pistons
Steeda stocks two forged BRC pistons for all 4.6 engines. The dished piston ($650) is targeted at supercharged Two-Valves, but can be used in supercharged Four-Valves needing a bit more safety margin. Spinelli says most owners of supercharged Cobras don’t want to give up any compression, so they also stock a flat-top piston. The flat-top is also sold to those building max-power, naturally aspirated Two-Valves. Steeda’s rods are built by Manley and offered in your choice of forged or billet. Either is much stronger than the cracked-cap stock rods, especially those in ’96-’98 Romeo Two-Valves.
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Any forged piston is a considerable improvement over the stock hyper- eutectics, but Steeda goes a step further toward durability. They offer ceramic top coatings and dry-film-lubricant skirt coatings ($170) designed to shore up the pistons against occasional duress. “If your tuneup is way off, you’ll blow a hole in this piston just like any other piston,” Spinelli explains. “The reason we coat is because it’s super-hot one day and you’re running the car in bumper-to-bumper traffic, you pull out and dive on the gas pedal, and the thing starts detonating. This coating is going to help save that piston.”
138_16z Ford_mustang_gt Piston
Steeda custom-orders its dished pistons with a 0.912 pin, which is the 5.0 pin dimension, rather than the stock 0.822 pin. “A much bigger pin gives you better pin loading,” Spinelli says. “I don’t think that trying to push the 400-plus-horsepower envelope on a 0.866 pin is such a good idea.” Steeda also removes the pin offset feature in the stock piston. It’s supposed to reduce piston slap, but Spinelli says the difficulties it presents to an engine builder outweigh the minor benefits.
138_17z Ford_mustang_gt Block
If you already own a ’99-2000 Mustang, you’ve got a good head start on a solid-performance Mustang. You can see 360 rear-wheel horsepower with just a supercharger. Not only do the New-Edge Mustangs pack better intakes and cylinder heads, they feature much stronger cylinder blocks as well. According to Spinelli, the Windsor block also has stronger main webbings and an improved oil design. The improved main design includes larger main caps and dowels wedged between the caps and block to reduce deflection. The Windsor block uses a slightly revised timing chain tensioner setup as well, but by the time you read this Steeda will offer a conversion kit for owners of pre-’99 Mustangs.
138_18z Ford_mustang_gt Block
This Windsor Two-Valve block’s number-three main will accept a steel Cobra crankshaft without clearancing, while the early blocks require a bit of grinding on the number-three main. Windsor blocks also share the bearing set with the aluminum Four-Valve block. “If you were to tell me you wanted to build the all-out piece,” Spinelli says, “I would suggest you buy a ’99 (-and-up GT) block.” Steeda sells the Windsor 4.6 block for $850.
138_19z Ford_mustang_gt Crank_shaft_install
Here, Steeda’s engine builder, Steve Chichisola, drops in a Cobra crankshaft. The steel Cobra crankshaft is the foundation for all of Steeda’s Two-Valve short-blocks. Retailing for around $550, this forged-steel crankshaft is a bargain. It’s much stronger than the cast-iron crank in Two-Valve cars, but it requires an eight-bolt flywheel, whereas the ’96-’98 Romeo Two-Valves used a less sturdy, six-bolt flywheel mounting flange.
138_20z Ford_mustang_gt Flywheel
As mentioned earlier, the Windsor Two-Valves no longer use this six-bolt flywheel, which is good news for two reasons: The eight-bolt flywheel offers a much stronger attachment mechanism, and owners of Windsor Two-Valves can more easily upgrade to the eight-bolt Cobra crankshaft.
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One of the weakest aspects of the 4.6 engines is their torque-to-yield fasteners. These one-use fasteners must be replaced after a block is bolted together and machined. Worse yet, they tend to stretch when hit with lots of boost. “The reason it’s pushing head gaskets is because it’s got this big, 10-inch-long, torque-to-yield head bolt in it,” Spinelli says. “So, because of the cylinder pressure, it’s yielding. It lifts the heads off the deck at boost and pushes water out the guy’s overflow puke tank. If you go back to 8 pounds of boost, you’ll never know it happened, because the thing will seal and run, and the car will run around town all day long and the car won’t overheat and do things like an old 5.0 did.” No one ever reduces boost on purpose, so Steeda recommends ARP head studs and quality gaskets to eliminate the problem. Currently, Steeda uses copper head gaskets and stainless steel rings to corral ultra-horsepower cylinder pressure, but a new Fel-Pro composite gasket and the wire ring should provide the answer for most 4.6 owners.
138_30z Ford_mustang_gt Cylinder_head
Combined with the copper gasket and ARP studs, Steeda chooses to groove the cylinder block and place the stainless steel ring in the cylinder head. The ring then presses the gasket into the groove and provides as good a seal as you can get. Spinelli says they groove the block and not the heads as it’s the most durable method.

Back in 1996, the concept of supporting the Mustang GT's new Two-Valve engine as a performance player was a stretch. Much like the freshly fuel-injected '86 Mustangs were in their day, the '96s were anemic compared to their 5.0 forefathers. The GT engine made 5.0-like torque, but ran out of airflow steam at the top end--where you'd think an overhead-cam engine would excel. As a result, most of the modular action amounted to Cobra owners bolting on superchargers to the giddy tune of 400 hp.

Because all the early action was in the Cobra pit, we thought Ford Racing Performance Parts (nee Ford Motorsport SVO) was on the wrong track by developing, albeit slowly, parts for the Two-Valve engine. Surely, people wouldn't spend the money to hot-rod the GT, when Cobra power was so easily, if expensively, attained.

Well, we were wrong and we'll freely admit it. Yes, there are still a lot of Cobra owners building big power, but the '99 GT has shown us the potential of improved induction on the Two-Valve. These engines can make as much, or more, power than the pushrod engine in a quieter, more efficient manner.

Though the block party thrown by Ford in 1999 is being enjoyed by hordes of enthusiasts, Steeda Autosports in Pompano Beach, Florida, actually started the celebration back in 1996. "The reason we jumped on the Two-Valve early was because it's the future. This is the motor of the millennium," Dario Orlando, the principal at Steeda Autosports, says. "Everybody is afraid of change, but change is progress, so that's why Steeda jumped on the bandwagon immediately. As you can see with 3-1/2 years of development, just with supercharging and bolting on parts, 530 hp to the rear wheels is nothing to sneeze at."

The 530hp Mustang in question is Steeda's '96 GT drag car, which has been a test mule for overcoming the durability and tuning challenges incumbent with a new engine. We drove the car when it was making only 500 hp and can happily report it made that power without sacrificing a hint of driveability. The car features a built Steeda short-block topped with FRPP cylinder heads and intake, and fed by a Vortech T-Trim. The car hauls, but only because the bottom-end can handle the power.

"There are guys all over the country who are putting FRPP heads and intakes and Vortech superchargers on and saying, 'Hey man, it runs great. We aren't having any problems,'" Steeda's New Vehicle Program Manager Nick Spinelli explains. "They are way overtaxing the piston at that point. Just because it works doesn't mean it's the right thing to do. That's our outlook. It works, but eventually you'll start breaking pistons."

As good as the 4.6 engines can be, they are limited by a glass jaw in the form of hypereutectic pistons. These composite pistons prove fragile when subjected to detonation. The engine is also afflicted with compliant cylinder-head fasteners and passable cylinder-head gaskets. According to Spinelli, these factors mean you can go up to 11-12 pounds of boost with a stock engine, a safe electronic tuneup, and good gaskets and fasteners.

If you want to couple a power adder with FRPP heads and intake, or an aftercooler, then it's time to build an engine that will withstand the increased cylinder pressures. Fortunately, Steeda has already done the development work on its '96 drag car, and they have the short-blocks and rotating assemblies to prove it.