UD pulleys and idle RPM
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Joined: Oct 2005
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From: Miami, FL
UD pulleys and idle RPM I want to get U/d pullies soon, and I noticed my A4 idles at a somewhat high 750. I've been wondering if thats why my gas mileage has been bad but I don't think it makes a big difference. But this may help me out when I get my 25% UD pulley.
Only thing is I usually don't use accessories much, so should I also get my idle lowered with a tune or keep the U/d pulley with my high idle? And I hear claims of 2-3 mpg gains and 12-15 hp. I find that hard to beleive, but has anyone seen those kinds of gains?
Thanks for the help.
Only thing is I usually don't use accessories much, so should I also get my idle lowered with a tune or keep the U/d pulley with my high idle? And I hear claims of 2-3 mpg gains and 12-15 hp. I find that hard to beleive, but has anyone seen those kinds of gains?
Thanks for the help.
you want to keep your high idle because with the u/d pulley youll need to keep the battery charged a little better and to help stop your lights from dimming when stopped. my u/d pulley gave me a 1tenth and 1mph in the quarter.
Are you basing your 750rpm idle off the factory tach? If so, understand that the factory tach is very inaccurate, especially at idle. From the factory, your idle is set at 550rpm in gear and 650 in gear w/ac on. In P/N it is set at 650. My 98 factory tach showed me idling @850 when I was stock and monitoring it in HPTuners verified that it was actually 550.
I also have an ASP underdrive crank pulley and bumped my idle up 100 rpm and have zero charging problems.
I also have an ASP underdrive crank pulley and bumped my idle up 100 rpm and have zero charging problems.
Originally Posted by pla-tym2
7-10 rwhp gain is more like it with a UD pulley. Set you idle @ 650rpm's with either pulley.
Another option is to set idle at 650rpms and get the overdrive alternator pulley. You won't gain as much from the underdrive pulley but you will have a lower idle. Also another reason I would recomend setting idle at 800rpms is the a/c will blow normal.
