Of all measures to increase horsepower and torque of your factory engine, stroker flywheels are among the most effective. Boost your stock displacement 61” or 74” Knucklehead, Panhead or Shovelhead up to 84 cui or 1380cc (@ 3-7/16” bore) and experience arm stretching performance and a significantly increased fun factor. <br />Especially with original engine cases these 4.5” stroker flywheels are the way to go. If any, they require only minor modifications for installation and unlike with machining for Big Bore cylinders cases become not weakened. Consequently, engine life expectancy is near stock.<br />All versions are of Torque Monster type with thick left flywheel as original and require special stroker pistons, which are also available. <br />Manufactured from 80-55-06 ductile iron blanks, which are then heat treated. The 80,000 pound tensile strength blanks undergo an exacting 20-step manufacturing process, utilizing both CNC and conventional precision milling and machining. This insures accurate surfaces, legendary reliability, and excellent „truability“, an absolute necessity when setting up high performance motors to blueprint specifications. With pre-installed and replaceable connecting rod thrust washers, providing increased service-life and restorability.<br />Recommended for qualified mechanics only, because the flywheels need to be balanced and clearances in engine cases need to be checked.