Harley-Davidson® Screamin’ Eagle® accessories offer more than 25 different street-performance stage kits that can increase the power and performance of Harley-Davidson® Twin Cam and Evolution® engines. Designed with components engineered to work together as a system, these kits eliminate the trial-and-error testing often required when making engine modifications – a rider simply defines a performance goal and chooses the Screamin’ Eagle stage kit that delivers the desired performance.

All Screamin’ Eagle stage kits, from basic Stage I Air Cleaner Kits to comprehensive kits for Twin Cam 103™ engines like the all-new Screamin’ Eagle Bolt-On 110 Stage V Tire Shredder Kit, are engineered to achieve two goals:

1. Increase the volume of air and fuel that flows through the engine.

2. Improve combustion efficiency to generate more power from the fuel delivered to the combustion chambers.

Stage Kit Design and Testing

All of the components in the engine or attached to it need to operate in harmony to produce optimal power. Screamin’ Eagle stage kits do just that because, prior to going into production, they go through an extraordinary amount of research, design, testing and development, including the following elements.

Simulated Engine Design: Using sophisticated engine development software, engines are run in a virtual world after all parameters are loaded into the program. Engineers input engine data such as cylinder bore, piston stroke, connecting rod length, compression ratio, intake and exhaust port flow, throttle body diameter and valve-train specifications, including valve size, valve lift and valve opening and closing times. Engineers usually run several different engine configuration simulations before achieving the performance objectives in the engine simulation program.

Prototype Testing: The team builds Screamin’ Eagle prototype engines and runs dynamometer tests to prove or disprove the calculated performance objectives. This often requires several iterations of design to meet the objective of optimal performance and
drivability.

EFI Tuning: Every stage kit requires a recalibration of the EFI system. This is accomplished by creating a new ECM calibration incorporating hundreds of fuel-delivery variables and myriad spark timing changes to optimize power at all engine speeds and loads. This is accomplished through many hours of dyno and on-road calibration development.

Emissions, Durability and Sound Testing: Street-performance stage kits are tested for vehicle sound and exhaust emissions and then certified compliant for street use in the U.S. Durability testing validates that the performance configuration will deliver high performance with exceptional reliability. Lastly, drive-by sound testing is performed on a certified track, following a complex set of vehicle operations parameters measured by sophisticated testing equipment.

Creating the Comprehensive Solution: The Screamin’ Eagle team then finalizes each kit to ensure it meets performance and budget targets. The kits are easy for the consumer to comprehend and deliver great value.

Screamin’ Eagle kits are engineered to deliver proven and reliable street performance while maintaining dependable operation and regulatory compliance. Screamin’ Eagle product development takes the guesswork out of boosting Harley-Davidson motorcycle performance.

For more information, visit www.h-d.com.