As of 2014, NASCAR mandated specifications include a carbureted V8 engine with a maximum 5.9-liter capacity (358 cubic inches). The current limitations are designed to encourage the engine parity of vehicles, which generate an average of about 850 horsepower. Most NASCAR engines are built from scratch, with the average unit taking teams roughly 100 hours to assemble and ranging in cost from $45,000 to $80,000.
According to NASCAR CEO and Chairman Brian France, further restrictions to reduce output by as much as 100 horsepower are in the early planning stages. The anticipated move is expected to result in increased corner speeds and to extend the life of engines to more than one race.
Sprint Cup engines, as of 2014, come from one of five manufacturers: Chevrolet's ECR Engines and Hendrick Motorsports, Ford's Roush-Yates Engines and Toyota's TRD and Triad Racing Technologies. NASCAR rules also limit teams to using the blocks, cylinders and intake manifolds from the castings of approved manufacturers.
Modern NASCAR engines spin up to 9,500 revolutions per minute, enabling vehicles to reach speeds well over 200 miles per hour. As a safety measure, restrictor plates limiting airflow to reduce speed are placed on cars in races held at Daytona International Speedway and Talladega Superspeedway, the two biggest tracks in the Sprint Cup series.