One look under the hood and...
One look under the hood and it's easy to see what all the excitement is about. A Paxton supercharger and a Carroll Supercharging custom water/alcohol injection system nearly doubles the horsepower of the factory's 230hp L98 engine. In "Bird Under Pressure" (HPP June '88), author D. Randy Riggs described the V.H.O.: "Supercharging has always been a relatively easy way to gain a clump of additional horsepower, and Carroll proves the point. The Paxton arrangement in his Formula 350 is essentially bolt-on power, pure and simple. He's taken existing components and assembled them into a package that feels exotic, but isn't, yet certainly performs like an exotic when it comes to straight-line acceleration."
In June 1988, High Performance Pontiac featured a hot, new limited-edition Firebird called the Supercharged 350 V.H.O. Formula. At a time when Pontiac's flagship Trans Am GTA boasted a meager 230 hp, the V.H.O. Formula was one tuner's attempt to return Firebirds to the high-performance arena, with a Paxton centrifugal supercharger and a proprietary water/alcohol injection system, which allowed it to safely achieve 400 hp and a quarter-mile time of 13.4 seconds.
How It Came To Be
Greg Carroll of Carroll Supercharging, now called BlowerWorks (www.blowerworks.net), in Wyckoff, New Jersey, was the engineering mastermind/entrepreneur behind the project. "I had an '84 Trans Am that I custom supercharged through a blow-through carb box I built. I enjoyed it as a daily driver," he recalls.
In 1987, Greg developed a business plan to offer high-performance Firebird conversions to Pontiac dealers in the Northeast. He came up with the name V.H.O., an acronym comprised from the words Very High Output. "The name V.H.O. had a great sound to it, and still does," Greg says. "It was a powerful name, just like GTO."
Greg ordered a Silver Metallic '87 Formula for the prototype, equipped with the optional 350ci L98 engine instead of the standard-equipment 305ci LB9. He chose the Formula over the Trans Am because he wanted to include the three-gauge set (fuel pressure, manifold pressure, and trans oil-pan temperature) that he inserted into his '84 Trans Am's hood-bulge; for '87 the Formula had a hood bulge and the T/A didn't.
Once his factory-fresh Formula was delivered, Greg got to work on the supercharger conversion. "In the mid-'80s, Paxton offered the only centrifugal blower in the market," he explains. "Its most popular one at the time was an SN-89, which was capable of 5-8 pounds of boost. I told Paxton what I was going to do and bought 12 blowers from them. I put together the air tubes myself, and J.T. Granatelli made the prototype brackets for me."
This may look like a run-of-the-mill...
This may look like a run-of-the-mill '88 Formula 350 from twenty feet away, but it's actually a 350ci Supercharged V.H.O. Formula created by Carroll Supercharging. Only three of these super-rare Formulas were ever built, and this one was on the cover of High Performance Pontiac, when new, way back in June 1988.
Carroll Supercharging preferred...
Carroll Supercharging preferred the interior trim of the Formula, and left the cabin mostly stock But these custom-made, factory-appearing switches were installed on the dash to activate the injection system.
His next step was to install one of his proprietary water/alcohol-injection systems (tweaked from his blown Mopar 340 that he worked on back in 1970), which would cool the combustion process and prevent the engine from detonating.
"I found that a 50/50 mix of water and alcohol prevented the water from freezing in the wintertime and enhanced water vaporization. In addition, the water/alcohol mixture acted as fuel as well," he says. Although Greg had to figure out the right volume to deliver into a 350-cid running 5 to 10 pounds of boost, (around 15 gph), he attributes much of his education to Sir Harry Ricardo, an English engineer from the early 20th century.
Greg finished the V.H.O. prototype in the summer of 1987 and began calling on dealers for advance orders. "I demo'd it to Jim Salerno, owner of Salerno Pontiac in Randolph, New Jersey, who was a progressive thinker and knew that the V.H.O. Formula would bring traffic into his dealership," Greg recalls. "He bought one on the spot and talked S&M Pontiac in Sussex, New Jersey, into buying one, too. [Both were '88 Formulas.] That accounts for all three V.H.O.s I built," he says.
So what happened? Why weren't dozens or even hundreds of V.H.O. Formulas put into the retail market?
According to Greg, even though the supercharged coupes were light-years ahead of their time, the $10,995 retail cost of the conversion left some dealers skeptical and worried about the GM warranty.
"I quickly came to realize most GM dealers wanted nothing to do with any aftermarket engine mods," Greg says. "They just wanted to sell cars, not to go out on a limb and take warranty risks with a limited-edition, aftermarket tuner car. The conversions were just too expensive for the Firebird market for the time."
Consequently, he turned his focus to developing C4 Corvette supercharger kits, which he still builds, markets, and sells to this day.
Likewise, Carroll Supercharging...
Likewise, Carroll Supercharging wanted the boost gauge to look like it was factory designed for the Formula.
Even from a profile, it's...
Even from a profile, it's difficult to see that this Firebird differs than any of the 13,475 Formulas produced in '88. The body remains entirely stock, as does the new-for-'88, Formula-specific Hi-Tech 16x8-inch aluminum wheels with silver WS6 center caps.
According to Carroll Supercharging,...
According to Carroll Supercharging, Paxton was the only performance company mass-producing a centrifugal-style blower in the mid-'80s. This unit, the SN-89, was good for 5-8 psi of boost.