Best Pulley

[M3 Esq]

Originally Posted by swamp2

Fantastic. Thank you!

Anyone have the OEM pulley diameter?

I measure 124mm. This is not exact. I measured using a tape measure and eyeballing where the center is. I recently installed the Dinan pulley so I have the OEM one sitting on my work bench.

[MilehighM3]

It looks like Andrew measured at the bottom of the belt grooves, but that can't be confirmed given the angle of the photo. At most he measured the top of the belt ridges. I guess I should've measured mine prior to installing today to confirm. Ah well!

[swamp2]

Now we are making some progress. Thanks folks! I used the average of the two reported measurements for the OEM pulley (i.e. average = 122 mm). That can easily be changed once some one gets a caliper on it. You could also wrap it with a non stretchy piece of plastic or tape and then unwrap and use diameter = circumference/pi. That should be quite accurate.

Come on vendors, let's see some more measurements!

[swamp2]

Originally Posted by Bmw135er

It looks like Andrew measured at the bottom of the belt grooves, but that can't be confirmed given the angle of the photo. At most he measured the top of the belt ridges. I guess I should've measured mine prior to installing today to confirm. Ah well!

I would say you can not tell at all from the picture if he measured inside the troughs or on top of them. Andrew, what did you do?

All new measurements welcome!

[SflBimmer8484]

Originally Posted by Bmw135er

It looks like Andrew measured at the bottom of the belt grooves, but that can't be confirmed given the angle of the photo. At most he measured the top of the belt ridges. I guess I should've measured mine prior to installing today to confirm. Ah well!

I measured it correctly from the top crest of the grooves.

[Robmaster]

hey Andrew, did you have a DIY guide for the installation of the pulley???

[M3 Esq]

Originally Posted by Robmaster

hey Andrew, did you have a DIY guide for the installation of the pulley???

Just google AA pulley DIY. It should be the first hit.

[SflBimmer8484]

Not sure why the pdf is missing from our support section but ill get it up on there asap!

Instructions: http://www.vividracing.com/catalog/p.../Product77.pdf

Belt Routing: http://www.activeautowerke.com/insta...%20onwards.jpg

[swamp2]

I sent emails to each OEM that I could inquiring about pulley diameter(s). MS website had errors that prevented sending an email and Dinan website was down. Just guessing, I would say half of less of those I contacted will tell me their diameter(s), like it is some big trade secret or something. Hopefully, they will be reasonable and realize that savvy buyers want to know some objective facts about the products they are interested in. After all a pulley is a SYSTEM and their are so many details to getting a good design beyond just the single diameter that dictates performance. We'll see.

The community here would appreciate any additional efforts to complete this comparison.

[BPMSport]

Originally Posted by swamp2

I sent emails to each OEM that I could inquiring about pulley diameter(s). MS website had errors that prevented sending an email and Dinan website was down. Just guessing, I would say half of less of those I contacted will tell me their diameter(s), like it is some big trade secret or something. Hopefully, they will be reasonable and realize that savvy buyers want to know some objective facts about the products they are interested in. After all a pulley is a SYSTEM and their are so many details to getting a good design beyond just the single diameter that dictates performance. We'll see.

The community here would appreciate any additional efforts to complete this comparison.

I have had the RD pulley on my car since 2008. No issues. Although the car does get hot (coolant temperature) on the track in extreme conditions, so I have had thoughts of going back to stock.

Personally if I could go back and do it again I probably would have left it stock. Gains just are just not significant enough for the tradeoffs.

When you under-drive the water pump you loose a little bit of cooling, when you under-drive the power steering pump you'll lose a bit of low speed assist in certain conditions. Most of the time both of these are not significant concerns, but I did see a difference in temperature on the track with the water pump being under-driven (in 100F+ ambient temperature, and a consistent railing - 25 minutes at a time between 7k RPM and 8600, + a track that doesn't offer much cooling time on straights).

Hope this helps. The money is better off being spent on a tune and exhaust. I'm very curious how much my RD pulley underdrives the accessories, but being that it's been installed for 4.5 years I can't check easily. The US head of RD was just here about 30 minutes ago, I should have asked him.

PS: Really liking the AA install guide.

[swamp2]

Originally Posted by Mike Benvo

I have had the RD pulley on my car since 2008.
...
Personally if I could go back and do it again I probably would have left it stock. Gains just are just not significant enough for the tradeoffs.

Thanks Mike, a very valuable perspective. However, from a $/hp ratio perspective pulleys are hard to beat. If only your software had a similar $/hp ratio.

P.S. You did my software update (remote) and we've emailed about your tune as well.

[lukester]

Hi guys.
I think I have to add some more in deep information why the pulleys are more than worth the money.

I'm using the Macht Schnell kit and compared to the BMW stock ones it's one of the solutions which you need to keep your power steering oil from boiling!

Stock BMW ratio to the power steering pump is ~1.11
Macht Schnell is ~0.89

What does that mean? Easy math. When your engine is at 8000rpm the power steering pump is not at ~8900rpm but at ~7120rpm.
That's ~25% less rpms on the power steering pump!

Why is that so important?
Well - everybody who tracks his car knows about the boiling oil.

As some know I'm driving a lot on the Nordschleife - problem of the track. Due to some jumps and many corners it adds additional load on the power steering system.

Step 1) With the Macht Schnell pulleys I was able to do some laps without a boiling oil.
Step 2) To get it really rock solid even during hot sunny days you'll need an additional power steering cooler.
If you look at the BMW GT4 power steering cooler you'll see that it's much larger than the stock e9* M3 cooler. They didn't change it for the racecar without reasons.

Here's my solution. This cooler here is added in a row to the stock one.

[shrimpp5]

I love my Macht Schnell Pulley, very noticeable gains on the butt dyno!

[swamp2]

Originally Posted by lukester

Here's my solution. This cooler here is added in a row to the stock one.

Some questions: With stock pulleys your PS oil boiled, then when changing to MS pulleys your oil did not boil? That does not make sense.

Also isn't your additional PS cooler blocking a very significant portion of the main radiator? Isn't that just trading one problem for another?

[MilehighM3]

The power steering fluid shouldn't get near as hot since the pump speed is now slower than factory. Which may or may not keep it from boiling. It just depends on the track conditions and driving style. It's a huge problem on the Caymans. Any one with more than 1-2 track days knows the short comings of the lack of power steering cooling. Adding an improved cooler and an under drive pulley on that platform cured my overheating issues leading to leaks and pump failures 100%.

[swamp2]

Got a nice update from Rogue that they use a 16% reduction. In our table that means 84%. Since they use a 2 pulley system (which is specifically not to underdrive certain systems) I have asked them to clarify that. Hat's off to Rogue for sharing information openly.

[swamp2]

Updated.

Link to edit.

[urBan_dK]

The Rogue and Macht Schnell kits provide a power steering pulley. If the pulley is larger than stock, it serves to further underdrive the power steering pump. If it is smaller, it restores the pump speed somewhat back to the factory specification. I just installed my Macht Schnell pulleys and didn't check to see the size difference.

It is erroneous to say the MS kit doesn't underdrive AC. since the crank pulley diameter is smaller for both belts, it must.

[swamp2]

Originally Posted by urBan_dK

The Rogue and Macht Schnell kits provide a power steering pulley. If the pulley is larger than stock, it serves to further underdrive the power steering pump. If it is smaller, it restores the pump speed somewhat back to the factory specification. I just installed my Macht Schnell pulleys and didn't check to see the size difference.

It is erroneous to say the MS kit doesn't underdrive AC. since the crank pulley diameter is smaller for both belts, it must.

Thanks for the info. I am using the best information I can find. The table/summary/comparison is a work in progress and the document is editable by the community here. You can also simply send me diameters and I'll do the calculations.

[urBan_dK]

Originally Posted by swamp2

Thanks for the info. I am using the best information I can find. The table/summary/comparison is a work in progress and the document is editable by the community here. You can also simply send me diameters and I'll do the calculations.

No prob. Find out from Rogue whether their power steering pulley is the same as stock diameter (meaning it will also run at 84%) or if they make it 16% smaller in order to restore to 100% of OEM power steering speed.

[urBan_dK]

Originally Posted by tom @ eas

MS uses two pulleys (not affecting A/C operation, which would also spin slower during everyday driving)

I see where Swamp's information on AC underdrive is coming from. How is it possible that the AC isn't underdriven since the MS crank pulley is smaller than stock and the AC pulley is not modified?

[Fsarc]

Originally Posted by urBan_dK

No prob. Find out from Rogue whether their power steering pulley is the same as stock diameter (meaning it will also run at 84%) or if they make it 16% smaller in order to restore to 100% of OEM power steering speed.

Great thread. I used to have the Rogue pulley and now have the AA. They are very similar in diameter if not exactly the same I believe. The Rogue power steering pulley is the same size as the OEM power steering pulley. The only reason Rogue and MS are changing the power steering pulley is to go from an OEM ribbed pulley to a flat design so they can use an off the shelf belt. AA took a different approach and felt the power steering pulley should remain OEM and therefore had to supply a custom made ribbed belt to fit. If the belt breaks you have to obtain a new one from AA- you can't run a pick up a new belt at the auto parts store. I'm very happy with the AA pulley.

Also the AA uses one off the shelf belt and one custom ribbed belt.

Here are some pictures of OEM, AA, Rogue and the belts supplied for AA and Rogue.

AA and Rogue pulley-













AA and OEM-





Rogue and the supplied off the shelf belts (Dayco is power steering)-




AA with off the shelf belt and custom ribbed belt-





AA, OEM, and Rogue PS and crank pulley (bottom)-





Rogue PS and crank pulley-





AA pulley installed showing belt routing and AA custom belt-