Underdrive Pulley (which Brand?)

ktlocklear · 29th November 2011, 18:52

So which brand does everyone go with? My concern would be to maintain proper engine temp and auxiliary functionality obviously.

There seems to be several brands...

Turner Motorsports: Gains; 18 to 22 HP and 17 to 21 Ft/lbs Torque

Evosport: Gains; Up to 30 HP and 24 FT-LBS Torque

Agency Power: Gains; 13rwhp and 18ftlbs of torque

RPI: Gains; 15hp+ and Torque??

Dinan: Gains; 6hp and 4ftlbs of torque

Rogue Engineering: Gains; Up to 30 hp and torque??

RDSport: Gains; Around 16hp and torque??

Any other brands?

Looks like Turner claims the highest numbers. They also claim fixed numbers which I like, along with Dinan and Agency Power...where as the others just give a guesstimated number or "up to".

Input would be greatly appreciated

Hasan Shaikh · 30th November 2011, 10:22

IMHO! The pullies will not gain you any power.

They will just take some of the load off the engine which will make the engine more lively and responsive. All the power gains don't make any sense to me.

How much of a load you will shed depends on the underdrive the pulley provides. Most of the manufacturers provide 13% underdrive. Dinan have a 16% underdrive pulley as well.

IMHO! There should be no difference in the results of a 13% underdrive pulley no matter who manufactures it.

ktlocklear · 30th November 2011, 17:00

makes perfect sense to me...but how do we know what the underdrive % is? I don't think any of the above brands lists that on their website. Maybe that is why the above numbers are so different from each other?

ktlocklear · 30th November 2011, 17:02

my bigger question still is.....what is the most popular brand people go with for their S85 motors that does not cause any issues?

Hasan Shaikh · 30th November 2011, 17:51

Most of te brands will tell you the %age of underdrive.

The most popular brands are RPI and Dinan.

ktlocklear · 30th November 2011, 20:59

Quote:

Originally Posted by Hasan Shaikh

Most of te brands will tell you the %age of underdrive.

Out of the brands listed above only 2 list the %age. Dinan is 13% and Agency Power, which says "about" 30% reduction

Looks like I'll have to email each company to find out. What is a safe number to stay under...13 percent?

irishbimmer · 1st December 2011, 01:06

I've a Dinan 13% underdrive in mine which the dealer installed...seems to work ok but wouldn't have any idea why the other numbers are so allover the map with the big claims...If you are happy with the RPI exhaust (I think that's what you have),I'd go for the RPI pulley. Stick with what brung ya...

Hasan Shaikh · 1st December 2011, 07:53

I have the RPI pulley. It's 13% underdrive.

I think 13% underdrive is ok.

Stealth 993 · 5th December 2012, 05:31

Sorry to bump a old thread, but I had this exact same question, and was wondering if there is any new info?

I'm leaning towards the Agency Power one, but can't really find people with them, or dyno's, I might just get the EvoSport one for $400.

guess55 · 5th December 2012, 05:45

i use Macht Schnell pulley

M3 forum has more brand's reps and member discussing about each pulley difference. some has two belts some has one.
Best Pulley - BMW M3 Forum (E90 E92)

it is good read thread, hope it can help