It's hard to tell if we're living in a golden age of performance or suffering through a stone age of disgrace. Modern technology has produced innovations like variable valve timing and gasoline direct injection. Hell, production cars transcended the 100hp/liter barrier nearly 15 years ago. On the other hand, the world's super geniuses still can't figure out how to harness the vast majority of energy produced by an internal combustion engine. To this day, only a third of an engine's energy is converted into power. Another third is absorbed by the cooling system, and the remaining third is wasted out the exhaust system. Apparently, those MIT grads and Stanford punks don't know jack-diddly.
Fortunately, someone figured out long ago that mounting a turbine wheel in an engine's exhaust tract recovers much of that wasted energy. Turbo technology has evolved dramatically over the years, and perhaps the best examples of its potential are the engines of F-1's turbo era during the '80s. Thanks to turbocharging, these monsters produced 1,400 hp from just 90 ci.
Contributing to the cause in a big way are Greg Johns (left) and Dalton Campbell of Pro Turbo Systems in San Antonio, Texas. Former disciples and employees of turbo maestro Corky Bell, whose book Maximum Boost is the bible of turbocharging. The Pro Turbo Systems staff has developed a cult following in the short time they've been around. Powering the world's fastest LT1 car (8.35 at 168 mph) is just one of their many achievements. PTS turbo setups power countless Outlaw and Pro-style drag cars, producing upwards 3,000 hp. The company's street kits border on full-race, and are available for everything from late-model F-bodies to C5 Corvettes. For this month's installment of The Insider, we had Greg enlighten us on the most common and controversial topics that encompass what some call the ultimate power adder.
The primary objectives when designing a turbo header are exhaust flow and durability. Most OEs opt for cast manifolds for their superior durability, but creating custom molds and hiring a foundry is too expensive and time-consuming for an aftermarket turbo kit. The next best option is building headers from mild or stainless steel tubing. "Stainless steel is a very good material for transferring heat energy to the turbo, but it's prone to cracking because its expansion rate is so great," explains Greg. "Stainless steel works fine for race applications that don't experience many heat cycles, but for the street, mild steel is a good compromise." The size of the tubing isn't too important, as long it doesn't neck down anywhere. "As you move from the primaries to the collectors, and then to the crossover pipe, you never want to have a decreasing diameter, because it creates tremendous backpressure once a turbo enters the equation." Likewise, a four-into-one header design usually provides the best flow. "A log-style header can be built to work fairly well, but it's usually only used when space or budget is at a premium. Dumping four primaries into one tube isn't optimal for flow."