Engine Performance Upgrades
MOVE MORE AIR & FUEL
Moving more air and fuel through the engine is the easiest (and most cost effective) way to make more horsepower and torque. A free-flowing air cleaner and matching tuned exhaust will add performance you can feel. To optimize engine performance (and to minimize the risk of engine damage), any changes to the intake and exhaust system must be accompanied by an increase in fuel flow. Re-jetting the carburetor or recalibrating the fuel-injection Electronic Control Module (ECM) will alter the amount of fuel and determine the precise moment at which fuel is released into the combustion chamber. Whenever you’re planning on making performance upgrades, make sure to consult your Harley-Davidson® dealer about the results you want to achieve.
Camshafts are a fundamental ingredient in the performance recipe, because they control the timing and duration of all major engine events. They are the primary means by which you can tune your engine’s horsepower and torque output. Every cam has unique lift and overlap performance characteristics, which means you need to select cams based on exactly the kind of power you’re looking for. If you need increased torque to launch a heavy bike off the line, or high horsepower to improve trap speed with a lightweight bike, Screamin’ Eagle® cams are available in a wide variety of configurations engineered to help you achieve the results you crave.
Developed specifically for fuel-injected Harley-Davidson® motorcycles, Screamin’ Eagle® EFI Stage Kits offer complete street-legal and racing performance configurations engineered to help you generate specific torque and horsepower gains at a given engine calibration. Eliminating all the guesswork and trial-and-error testing normally associated with engine modifications, Stage Kits include everything you need to enhance your bike’s performance, including big-bore cylinders, high-compression pistons, performance cams and high-flow air cleaners. Always consult with your dealer about any Stage Kit-related modifications.
PISTONS & HEADSOnce you’ve increased your engine’s displacement, you need to select complementary components that provide an ideal compression ratio for your specific situation. You can actually increase race engine power solely by boosting the compression ratio — the amount of pressure resulting from “squeezing” the air/fuel mixture — inside the cylinder’s combustion chamber. The shape of the combustion chamber, which is dictated by the design of the cylinder heads and pistons, also has an effect on how efficiently the air/fuel mixture is drawn into the cylinder, burned and then expelled. Screamin’ Eagle® Cylinder Heads offer a fusion of innovative port shapes and proven valve train components that produce race-winning power. And when matched with Screamin’ Eagle® Pistons, which feature a range of designs for faster burn patterns and specific performance results, they can help put the competition at your back.
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