• 20% and 25% Under Drive.
• SFI Spec. 18.1 bonded harmonic damper.
• High quality ‘All Steel’ construction.
• Robust outer ring retention design.
• Spin tested to 12,500 RPM.
• 60 degree precision engraved timing marks.
• Clear baked paint finish.
PRO/SPORT UNDER DRIVE DAMPERS
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 damper. The crankshaft damper functions as a combination crank damper and crank pulley on these engines. Under Drive dampers are smaller in diameter than stock production crank dampers 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 damper diameter without losing the torsion control required to prevent engine vibration and possible damage. The PRO/SPORT Under Drive dampers have been specially tuned to control crankshaft torsional vibration to stock production levels.
Dynamometer tests of the PRO/ SPORT 25% Under Drive damper on a 2005 Mustang 4.6L 3V engine at Livernois Motorsport in Dearborn Heights, Michigan produced a 13HP gain over a stock production damper.
Warning: Engine cooling and battery charging will be reduced and may not be adequate for city driving.
1996 – 2006 FORD MUSTANG 4.6L V8 ENGINES
• Available in damper or damper & pulley kit
• 25% Under Drive Poly-V groove design.
• All Steel water pump pulley is finished in black
• Steel Alternator pulley finished in black powder
coat (where supplied).
• Kit contains new crank bolt, installation bolt
& alternator bracket bolt.
GM LSI, LS2 & LS6 V8 ENGINES
• 25% Under Drive front Poly-V groove
• 22% Under Drive rear A/C Poly-V groove
on 98-05 Camaro & Firebird & 04-06 GTO
LSI & LS2 models.
• 7% Under Drive rear A/C Poly-V groove
on 97-06 LSI, LS2 & L56 Corvette models.
• 3/16” Keyway.
GM Truck Engines
• Available in damper only or damper & pulley kit
• 25% Under Driven Poly-V groove damper.
• 1.75” overdrive Steel Alternator pulley finished in
black baked enamel supplied in kit configuration.
Note: NEW OEM crank bolt (GM Part# 12557840) and
NEW belts are required when installing the dampers.
Dodge / Hemi Car and Truck Engines
• New under drive applications for 5.7L Hemi
Car and Truck!
• 20 % Under Drive Poly-V groove damper.