This Understated '06 GTO Seems Tame But Unleashes 700 Horses To The Wheels And 25 MPG Thanks To A Stout Engine And Twin Turbos
When the new GTO was introduced in model year 2004, many classic Goat owners scoffed at the idea that Pontiac put its beloved designation on what a few called a "hopped up Cavalier" from Australia. Now that some of them have actually had the chance to drive-or ride-in one, many have realized how much the vehicle has to offer, especially if the GTO's refined, but not too intimidating, appearance was used to its advantage by building a street sleeper.
Not everyone failed to recognize the GTO's greatness or its sleeper potential back when it was factory fresh, however. Rick Tirado, a United States Marine from Jacksonville, North Carolina, realized it in February 2006. He was at a Pontiac dealer to trade in his BMW Z3 for a Solstice. He had no idea the division began selling the GTO again, so he inquired about it. He took a peek inside and was pleasantly surprised at how nice the fit and finish was. That wasn't what he was really interested in, though. When he popped the hood and saw a 6.0L 400-horsepower LS2 staring back at him, Rick decided the Solstice could wait while he took the GTO out for a quick spin. That day, he drove home in a six-speed Phantom Black Metallic '06 GTO.
The rear haunches of the '06 GTO hint at the car's performance. Its rear spoiler adds to the sporty look, while dual exhaust outlets emit a muscular tone.
A 400hp LS2 should be enough for most sane people, but not Rick. He was fully aware of the aftermarket potential of this fuel-injected mill, thanks in part to frequenting www.LS1GTO.com. So from day one, he knew he was going to add more power.
The first modification he made was an STS rear-mounted turbo kit. This unique system delivered a bone-crushing 550 hp to the rear wheels. The STS not only helped Rick destroy his Nitto tires, it also retained the Pontiac's incredible streetability and fuel efficiency. Even with all that power and economy, Rick still wasn't satisfied with the GTO's performance. "The car was able to keep up with higher horsepower cars from a roll, but at the track it didn't reach the full 10 psi of boost until Third gear. By that time, I wasn't able to catch up."
In June 2007, Rick received orders to move to North Carolina, so he really began to tear into the Pontiac before he left. The STS Turbo Kit provided him with adequate performance, but he wanted more. This time around, his goal was a sharp increase in power, while retaining the poised street manners that originally attracted him to the new Goat.
The massive four-inch intake tube feeds the factory 90mm throttle body. Its diameter is necessary since the APS twin turbos fill the 370ci iron-block engine with over 12 psi of boost.
He contacted late-model GTO specialist Tom Tiberio, of Tiberio Performance in Tampa. Tom instilled in Rick the confidence that he could provide the Pontiac with the power he sought, while still being very driveable and comfortable. "Tom's attention to detail and craftsmanship are evident in every car he does," Rick says. Thus began the GTO's performance makeover.
The aluminum LS2 block was in perfect working order, but the increased boost levels would be better contained in cast iron, according to Tom. An LQ9 iron-block was chosen for its great reputation for durability when used with forced induction. It was sent out to Eisele's Automotive Machine in Tampa to receive all the machine work. While there, it was bored 0.030 over to 4.030 inches, achieving a 370ci displacement when combined with the LS2's 3.62-inch stroke nodular cast iron crankshaft. Eisele's polished the crank and chamfered its oil holes to improve high-rpm oiling (and an SLP high-volume oil pump was utilized to increase flow). The rotating assembly was balanced for smoother operation, resulting in more power.
After the block returned from Eisele's, Tom began to assemble the engine in his shop. Forged 4.7cc dished Diamond pistons (and rings) lowered the compression to a more boost-friendly 9.2:1 and were attached to forged Callies Compstar connecting rods. The bottom end also gained strength from a set of ARP main studs, while Federal Mogul bearings increased durability.