Super lightweight solid crank pulleys
***This advert is for billet underdrive pulley and a 5pk978 Auxilliary drive belt and billet tensioner wheel to allow you to run the OE springy tensioner arm***
AKA - The RnD Air Con Delete Kit
Aimed at sub ~450-500hp setups, these solid billet aluminium lightweight crank pulleys free up the engine from both inertial weight and parasitic drag from driving the alternator as fast (and A/C if you are retaining that). On setups below the 450hp region we have used these for years with no problems, and you can really feel the benefit on something fairly standard -> 350hpish, as the alternator and A/C add quite a lot of drag which soaks up a good bit of the available power.
The Standard pulley weighs just over 1.7kg, these are just 0.44kg. This allows the enigine to rev more freely, helping with downshift rev matching and general low gear accelleration, essentially a lesser but similar effect to lightening the flywheel.
They are also a smaller diameter than the standard pulley, so drive the alternator more slowly. This helps the alternator to survive at high rpm, and reduces the amount of effort required to drive it, so saving you power to go to the wheels instead. They have been sized to still drive the alternator hard enough at idle to keep the battery charged easily, no increased idle speeds are required. Same goes for the A/C Compressor if you elect to retian that.
We offer a few different packages to suit different setups, as listed below;
Under Drive Pulley Only, no belt
Under drive pulley with Billet Tensioner kit and belt - AKA the Air Con Delete kit - This kit requires you to retain the springy tensioner part of your original air con setup
Under drive pulley with belt for direct drive - Best used with an adjustable alternator bracket
Under drive pulley with belt for retaining A/C
For setups that are aiming beyond 450-500hp, we recommend to use a damped pulley (the standard pulley is not a bad option), as crank shaft harmonics can cause problems without the damping. For that setup we can provide the below kit;
Billet Tensioner kit with belt for Standard Crank Pulley
If you already have an underdrive pulley, then you could buy the tensioner pulley kit on it's own;
Billet Tensioner kit only
Billet Tensioner kit + belt to suit our under drive pulley (if you already have the pulley fitted)