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.