Tune Question Regarding Pulleys

[Baconbit]

Hey all, If I have a set of underdrives and I'm not gonna use the alternator pulley, do I still need a tune for the pulleys?

[RF Overlord]

You don't need a tune for underdrives regardless of whether you use the alternator pulley or not.

[Baconbit]

Ohhh I was under the assumption that you had to bump RPM's in the tune even if you didnt use the alt pulley, thought it had something to do with the crank pulley.

[SC Cheesehead]

Ohhh I was under the assumption that you had to bump RPM's in the tune even if you didnt use the alt pulley, thought it had something to do with the crank pulley.

You should be able to bump the rpm with your tuner without modifying other settings.

[Baconbit]

Well I don't have a tuner yet and I was curious if I could install the pulleys without a tune or would that give me problems?

[SC Cheesehead]

Well I don't have a tuner yet and I was curious if I could install the pulleys without a tune or would that give me problems?


Your idle will be lower after installation, accordingly, output from your alternator will be less than 12 volts at idle if you're running A/C and other accessories, that's the reason for bumping up idle rpm.

[fastblackmerc]

Hey all, If I have a set of underdrives and I'm not gonna use the alternator pulley, do I still need a tune for the pulleys?

There is no need to use the underdrive alternator pulley.

Installing the crankshaft & water pump underdrive pulleys will make the alternator turn slower.... that is why you are using underdrive pulleys.

You may or may not need to bump up the idle. As mentioned you may see your lights dimming at idle. If you OK with this then there is no need to increase the idle speed.

[Vortech347]

I love my UDP Crank but even with a slightly bumped idle a hot day in city driving with the A/C on has got to make my battery angry.