What is the "underspeed pulley" mod?

[Topless]

The underdrive pulley was developed for motorsport applications to preserve the power steering pump and slow the accessories on a motor that spends a lot of it's time at high revs (4-6K). A side benefit is that it reduces parasitic drag so you get a bit more torque/hp to the rear wheels at all rpm.

If you spend long hours stuck idling in traffic with headlights on and the stereo cranked you probably don't want it. If your car spends most of it's time between 2-3k rpm, you don't want it. If your car is a weekend joyride/track toy and you use all of your rpm range, this is right up your alley.

[Steve Tinker]

Originally Posted by Topless

If your car spends most of it's time between 2-3k rpm, you don't want it. If your car is a weekend joyride/track toy and you use all of your rpm range, this is right up your alley.

Topless - I fitted my Raby underspeed pulley 3 years ago, and most of my normal driving is between 2-3,5k rpm - no problems as yet.
When I installed the pulley, I temporarily connected my multi meter into the car to get some idea of the voltage output of the alternator. Above 1250 rpm, the voltage was back to standard @ 14.3v, so as long as your alternator is in good condition & you're not continually in heavy traffic with a high electrical load, you should be OK....

[Topless]

Originally Posted by Steve Tinker

Topless - I fitted my Raby underspeed pulley 3 years ago, and most of my normal driving is between 2-3,5k rpm - no problems as yet.
When I installed the pulley, I temporarily connected my multi meter into the car to get some idea of the voltage output of the alternator. Above 1250 rpm, the voltage was back to standard @ 14.3v, so as long as your alternator is in good condition & you're not continually in heavy traffic with a high electrical load, you should be OK....

Good to know, thanks for the meter read. Now go find a nice tight canyon road and wind her up!