Underdrive pulley and charging
#2
TECH Regular
Join Date: Sep 2004
Location: Raleigh, NC
Posts: 404
Likes: 0
Received 0 Likes
on
0 Posts
I would leave the stock pulley on. I have the overdrive alt pulley and it acts fine with no electrical loads on it at idle. But I have to keep the rpm above 1000 to charge above 13V when the a/c is on, and head lights are on. Not a big deal, and it is not going to drain your battery while you sit at a stop light. If I did it over again I would go underdrive alt or just stock alt. I think the ASP web site says what RPM will charge like normal, with each set up.
#6
The stock idle for an M6 car is 800rpm. The stock idle for an A4 car is 550rpm. They both have the same alternator. The majority of underdrive pulleys/dampers slow down the accessories by 25%. Do the math, you will be fine.