Volume III, Issue 10, Page 42

INSIDE THE CORVETTE LS7.R ENGINE

How does it differ from the production ZO6?

hen the production LS1, the first of GM's new-generation small-block V-8s, debuted in the fifth-generation Corvette in 1997, it provided a foundation for the Corvette Racing engine program. Before the introduction of the LS1 small-block V-8, almost every V-8 engine used for racing dated back to designs that originated in the mid-’50s. But the small-block V-8 that has been the cornerstone of America’s racing industry for more than 50 years is being replaced by derivatives of the LS series.

The race-prepared engines that power the Corvette C6.R race cars are more powerful than their showroom counterparts, but are still production small-block V-8s at heart. In fact, the heavy-duty blocks and cylinder heads designed by GM Racing engineers for Corvette Racing are based on the design of the production parts.
The ALMS (American LeMans Series) rules mandate the use of air restrictors to equalize the performance potential of the wide variety of cars that compete in the series. The size of the restrictor is determined by the vehicle’s weight, engine displacement, induction system (naturally aspirated or turbocharged) and other factors. The C6.R Corvette, for example, is required to breathe through two 31.8mm restrictors. These orifices are about the size of a 50-cent coin.

Much like the carburetor restrictor plates used by NASCAR on superspeedways, the ALMS air restrictors limit airflow through the engine, thereby controlling the horsepowerproduced. Moreover, ALMS officials can change the size of the restrictor orifice to maintain a level playing field.

“The 7.0L engine combination allows us to run relatively low rpm to maximize fuel economy and reliability while producing extremely high torque numbers that make the carsvery ‘driver-friendly’ on a road course,” explained GM Racing engineer John Rice.

Here's What's New!