Accessory drive systems have been made more compact on late model V8 engines, like the Ford 4. 6L and the GM LSI by machining serpentine belt grooves on the OD of the crankshaft The crankshaft functions as a combination crank and crank pulley on these engines. Under Drive s are smaller in diameter than stock production crank s which slows the speed of the accessories and reduces the H. P. required to drive them. Since performance and racing engine applications generally run at higher RPM, the water pump, alternator and power steering pump speeds can be reduced to save H. P. and still meet engine cooling, electrical and vehicle steering requirements. The trick is to reduce the crank diameter without losing the torsion control required to prevent engine vibration and possible damage. The PRO/SPORT Under Drive s have been specially tuned to control crankshaft torsional vibration to stock production levels. Dynamometer tests of the PRO/ SPORT 25% Under Drive on a 2005 Mustang 4. 6L 3V engine at Livernois Motorsport in Dearborn Heights, Michigan produced a 13HP gain over a stock production .
Accessory drive systems have been made more compact on late model V8 engines, like the Ford 4. 6L and the GM LSI by machining serpentine belt grooves on the OD of the crankshaft The crankshaft functions as a combination crank and crank pulley on these engines. Under Drive s are smaller in diameter than stock production crank s which slows the speed of the accessories and reduces the H. P. required to drive them. Since performance and racing engine applications generally run at higher RPM, the water pump, alternator and power steering pump speeds can be reduced to save H. P. and still meet engine cooling, electrical and vehicle steering requirements. The trick is to reduce the crank diameter without losing the torsion control required to prevent engine vibration and possible damage. The PRO/SPORT Under Drive s have been specially tuned to control crankshaft torsional vibration to stock production levels. Dynamometer tests of the PRO/ SPORT 25% Under Drive on a 2005 Mustang 4. 6L 3V engine at Livernois Motorsport in Dearborn Heights, Michigan produced a 13HP gain over a stock production .

More From This Category