Lidio Iacobelli's'05 GT Is A Real Alternative. It Runs 12s With Surprising Ease And An Automatic Transmission
Drag racer at heart, Lidio Iacobelli has always had a thing for automatics, and when the man in charge at Alternative Auto [(586) 463-0010; www.alternativeauto.com] went looking for an '05 GT, the new 5R55S five-speed auto was categorically on his must-have list. Like many quarter-milers, Lidio likes self-shifters for their consistency and reliability, but even he was surprised at how readily his 3,710-pound (with him onboard) GT knocked down the 12-second barrier in the warm spring air of Bradenton, Florida, after an abbreviated list of bolt-ons and some careful tuning.
Not surprisingly, the overall tighter gear spacing of the 5R55S in comparison to its four-speed ancestors is a prime contributor to the new car's alacrity. "At a glance, the 300-horse '05 GT with an automatic is certainly quicker than a 300-horse '04 automatic Mach 1," Lidio says. "It's very obvious and has been noted to be somewhere between three- and five-tenths in the quarter-mile. I have an '04 automatic [Mach 1] that I drove for six months last year with nothing done to it, and it's obvious that it's not the same. The new five-speed auto puts the 300 horses to better use."
Continuing with his comparison, Lidio opined that it's not just the tranny: "In my opinion, the new Three-Valve pulls more midrange than any 4.6 prior to this. I think it has more low and midrange than a Two-Valve, and definitely more than a Four-Valve. Coupled to some great ratios, when the car shifts, it has a great recovery. These are the things that have added up to make the automatic a quick Mustang." In this respect, Lidio feels the '05 needs a whole lot less rear-axle ratio than, say, a Mach 1, which demands at least 4.10s to do its best strip work.
Lidio also loves the way his S197 launches: "The '05 suspension, chassis, and all the things they did-making the wheelbase longer, the gas tank being in front of the axle, and the battery being behind the front struts-it's all paid off. The car squats. In my opinion, the car behaves like a Fox body with the battery in the trunk, the front sway bar removed, and a looser strut. It's unbelievable." This is not just Lidio's seat-of-the-pants imagination-his 60-foot times consistently hovered around the 1.90-second mark, and that was with SUV tires, of all things. His 275/40-20 rear skins are Continental 4x4 SportContacts, offered as optional equipment on the Porsche Cayenne.
All that said, there's obviously no way an '05 auto will threaten the 12-second mark right out of the box. A Michigan winter kept Lidio from running his down the strip in stock form, but we hear of high-13- to mid-14-second times being reported. Yet the 12-second shopping list seems affordably short-all Lidio needed were underdrive pulleys, a cold-air kit, intake runner-control delete plates, a slightly looser torque converter, and electronic tuning of both engine and transmission function. He didn't even touch the stock exhaust, and his aesthetic choice of 20-inch rolling stock added a hefty 18 pounds of rotating mass to each corner of the car. Lidio did replace the car's 3.31 gears with a set of 3.55s, but only to partially compensate for the 1.5-inch-taller-than-stock dub rubber. So, what we're saying is there was no effort to optimize or lighten the car for the strip. Lidio simply made his passes in the car's daily driven form, meaning these performance numbers should be repeatable by anyone who cares to follow this simple recipe.
Now for a closer look at the ingredients.
PulleysPulleys may not add horsepower, but they sure free up some from accessory driving duty. There's not much more to be said about this faithful old trick, except don't go too radical on a street car lest you find yourself low on alternator or water-pump output. Lidio reports no issues with this March combo.