"I wanted the fastest car possible that could still be driven on the street." It sounds like a quote that could have emanated from the fertile mind of nearly every gearhead in the world. The difference here is Robin Roberts of Glendale, Arizona, said it and set out to do it--with a Pontiac!
Many may recognize his 8-second '76 Trans Am thanks to its Second place finish at last year's Hot Rod magazine Pump Gas Drags. Now you'll learn just what went into that effort, and you'll be privy to what Robin has planned to win the event this year.
But first, where did this 37-year-old VP of Operations for WW Williams Detroit Diesel's quest for street supremacy begin? "My dad bought this Trans Am for my stepmom, and she drove it to work for 12 years," Robin told HPP. Originally it was a Cameo White 400 automatic car. "Then it was relegated to sitting in a shed for almost 10 years and was driven sparingly." Upon a visit back home to Kansas in 2000, Robin's dad offered to give him the Trans Am if he would race it. More specifically, his dad said, "Do anything you want with it--except sell it or put a Chevy motor in it!" Having been a street racer since high school, Robin saw the opportunity to realize his dream of building the "fastest street car."
Once back home, he bought a $50 '78 T/A parts car and swapped the doors, quarters, and floors into the rusty '76 in his home garage. The Pontiac was painted there, too, in GM Arctic White using Napa TecBase urethane for the two color coats followed by three coats of clear. The skunk stripes are '98 Viper GTS blue, and the spoilers are from the '78 parts car.
From there, three successive engine combos took up temporary residence in the bay, and as the Pontiac got quicker, Robin realized he didn't like the rear suspension because he couldn't get it to hook on varied surfaces (namely various streets). The decision to install a four-link and the necessity of a rollcage based on his e.t.'s pushed Robin and his big-cube T/A to the next level.
Taking Second at the Pump Gas Drags in 2005, the Pontiac's best pass of its three at Memphis was 8.79 at 161 mph on a 1.47 60-foot time. Following subsequent shock tuning and four-link adjustments, the Pontiac hooked better, and therefore the nitrous could be engaged sooner. As a result, the T/A's best pass as of this writing is an 8.53 at 162.5 mph on a 1.28 60-foot at Robin's home track, Speedworld Motorplex, just outside Phoenix. Now let's learn how it got that fast.
With 537 cubes of IAII engine topped with wide-port E-heads, a stout roller cam, and lots
Under the hood is an IAII block featuring a 4.36-inch bore and a 4.5-inch stroke crank to equal 537 ci of nasty nitroused fury. The nitrous system could be a story unto itself and Robin is quick to tell you, "When working out the combination, any engine concept that didn't directly aid a nitrous application was thrown out. We looked at cylinder pressure and spent time studying where it rises and peaks on nitrous. In the lower ranges, there isn't much cylinder pressure. But it builds up substantially when nitrous comes on and the revs rise."
The foundation of the system is a pair of NOS Big Shot kits for use with a 4150 Holley carb, but Robin wanted to improve the delivery under the carb. So instead of using the plate supplied by NOS, he grafted the NOS spray bars for a 4150 carb, which are about an inch narrower than the Dominator carb that he is using, into a Dominator-sized clover-leaf spacer to concentrate nitrous spray in the center of the manifold.
To handle and take full advantage of all the squeeze, the block was fitted with a Crower billet crank and 6.700-inch Crower billet steel rods with Ross custom-forged nitrous pistons, after the machine work was performed by Kelly Blubaugh at WFO in Phoenix. Why a 6.700-inch rod and not a 6.800? "So there is room to increase the compression height and lower the ring pack on the pistons to provide as much material as possible at the top of the piston for durability with nitrous," Robin said. "Some would think the rod is too short, but I was more concerned with the reliability and didn't worry about the rod/stroke ratio." A 12cc dish in the top of the piston keeps compression to 11.3:1, and C&A rings ensure it stays in the cylinders, as do O-rings in the block and copper head gaskets.