With more than 2,000 horsepower put to the pavement, Mark Koehler's drag radial Trans Am blew through the 2010 racing season with a best e.t. of 7.50 at 194 mph. The combination that generated that performance was a Kurt Urban-built 440-inch engine with the typical forged internals, a hydraulic roller cam, and a big, 106mm single turbo. And unless you're a regular in the pits at the LSX Shootout and other drag radial competitions, you may be surprised to learn the foundation for Koehler's engine isn't one of the dedicated racing blocks on the market, but a production 6.0-liter LS2 block-albeit one with some pretty serious reinforcements from ERL Performance.
"It's been a remarkably solid engine and through an entire season of racing, we didn't have any bottom end issues," says Koehler, a member of that group of turbocharged, envelope pushers known as the Ohio Boys. "Kurt [Urban] did a great job building and tuning the engine, but that ERL Superdeck block really held up to all the boost."
Before we get into how ERL modifies the block and the materials they use, lets get to the root of the issue: Why production blocks fail in extreme high-performance combinations. In the most basic terms, they weren't designed to be used as 1,000-, 1,500- and 2,000-horsepower racing engines. More specifically, they weren't designed to support the cylinder pressures those engines experience, especially under high boost. An LS1 engine, for example, has combustion pressure of about 1,100 psi, although a high-boost engine producing more than 1,300 horsepower and 1,400 lb-ft of torque will generate about three times that pressure: 3,000 psi. In regular-production aluminum LS1 engines, it's the cast iron cylinder liners that take the brunt of the abuse. They crack. It's a similar story for other production LS engines. Even the iron (truck) blocks, which have long since been popular among power-adder engine builders, just aren't designed for that level of stress.
"All things considered, GM did a really good job in the design of the LS engine, but it was designed for passenger vehicles, not 1,500-horsepower True Street cars," said ERL's Sean Ragains. "If the tune is on the ragged edge or the boost pressure is really high, it doesn't take much to break the liners, decks, or the block itself."
A dedicated racing block, such as the LSX, RHS or Warhawk, provides the added strength necessary to support the cylinder pressures of a high-power engine, but ERL has done a remarkable job building exceptional strength into production engine blocks. It's accomplished primarily by installing the Superdeck I system, which includes aluminum trusses to strengthen the block and ductile iron sleeves to withstand the combustion pressure. It may seem contrary to what seems necessary in a high-pressure engine, but ductile iron-which is infused with nodular graphite-is surprisingly elastic, which makes it extremely durable. The graphite nodules used in the material are spherical, which inhibits the formation of cracks. In fact, the name ductile iron is derived from its exceptional ductility, or its capacity to deform without fracturing.
"Ductile iron is three times stronger than the cast iron used in production LS engine block cylinder liners," said Ragains. "The sleeves we use have yield strength of about 110,000 psi, so they'll stand up to just about any amount of boost you can throw at them."