Underdrive pulleys

[DrphTa 5]

Has anyone used these pulleys on their own cars? You can buy kits which underdrive the powersteering, water pump and alternator etc.

Pros & Cons apart from a little more power?

Like this http://www.vividracing.com/catalog/evospor...es-p-13667.html

[thorburn 121]

How important do you consider your water pump to be? do you really want to give it less power.

If the alternator is still making enough power not to drain the battery under full load, then no problem.

I wouldn't use them on my car. A lot of money for power that won't really be felt at all.

A cheaper way of removing drag is ditching the air conditioning.

[Michael. 2313]

Yeah I looked into them a while ago for one of my Soarers, didnt think it was worth mucking around with, let alone spending what they cost.

[DrphTa 5]

Just an option im looking atm. Im replacing my powersteering pulley as it isnt "true" and making belt noise etc. cost is $150 AU. With the dollar being so strong with the US at the moment its not much more to get the other 2 pulleys.

[Richiz 0]

I use an UR (Unorthodox Racing) light weight Crank pulley for my 350Z, it seems to do the job, slightly faster revving up, also if you compare the stock crank pulley to the light weight, there's quite a big weight difference on the 350Z. I didnt bother with the accessory pulley because i didnt want to underdrive them. =)

Edited February 25, 2011 by Richiz

[MLM 57]

i have looked at these also and IMO they were a 'race' mod only.

If i deliberatly slow the pump i should be doing it either because i regularly overspeed the current set up ie lots of high rpm race driving or i know the current setup is over driven. I trust the bmw engineer to spec a pump to work over the most used rev range if not the whole rev range. I cant prove otherwise so for a street car the factory arrangement stays.

I would never remove the crank pully/harmonic balencer for fear of breaking somthing unless i had a proven replacement with significant gain. Prove to me any aux conponent is oversped or my car becomes race only and you have yourself a convert. My 2c anyway...

[antil33t 90]

Just snip the power steering belt off...

same gain for less money

[pureboiracer 0]

have experienced pretty average results from these in the past, imo dont waste the money...

[DrphTa 5]

Crank pulley is not an option.. And i wouldnt want to touch that one anyway.

Cheers for the info, doesnt sound like its worth it in the end.

You guys have much trouble getting the power steering pulley off without taking the front to peices?

[pureboiracer 0]

best way to change the power steer pully is to remove the pump and get a rattle gun on it.

but as i said its not worth doing at all, have dyno'd before and after (with another brand but essentially the same thing) and there was no change.

so my opinion is to put the money into something more worth while.

[DrphTa 5]

I think you may have missed that I need to change it. Removing the pump sounds like the way to go though

[pureboiracer 0]

my bad, missed that part, i only skimmed this topic, but yes remove the pump, much easier, and dont bother with underdrive.

[FIAT 131R 223]

I bought an under pulley kit for the E30 with a 3 litre M54 engine in it. The gain was minus 1 horsepower on the dyno. I went back to the supplier and told them I was annoyed that their claims about HP gains were bullshit. They did not take kindly to my comments and said that unless the dyno runs before the kit installation and after were on the same day, same dyno same temperature etc etc they would not accept that there were no significant gains.

My view is that it would be better to wait till winter and burn the $600 US that the under pulley kit costs and atleast you would get a little warmth from your money.