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You are here: Home > Balancers > Pro-Race Harmonic Dampers > Pro-Sport Underdrive


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.




GM - LS Series
GM LS1, LS2 & LS6 V8 ENGINES
  • 25% Under Drive front Poly-V groove accessory drive.
  • 22% Under Drive rear A/C Poly-V groove on 98-05 Camaro & Firebird & 04-06 GTO LS1 & LS2 models.
  • 7% Under Drive rear A/C Poly-V groove on 97-06 LS1, LS2 & L56 Corvette models.
  • 3/16” Keyway
more info
Ford - 4.6L Modular Motor
1996 – 2006 Ford Mustang 4.6L V8 Engines
  • Available in damper or damper & pulley kit configuration.
  • 25% Under Drive Poly-V groove design.
  • All Steel water pump pulley is finished in black powder coat.
  • Steel Alternator pulley finished in black powder coat (where supplied)
  • Kit contains new crank bolt, installation bolt & alternator bracket bolt.
more info
Chrysler - Late Model Hemi
Dodge / Hemi Car and Truck Engines
  • New under drive applications for 5.7L Hemi Car and Truck!
  • 20 % Under Drive Poly-V groove damper.Dodge / Hemi Car and Truck Engines
  • New under drive applications for 5.7L Hemi Car and Truck!
  • 20 % Under Drive Poly-V groove damper.
more info