How much does this help? I have been doing a lot of fine tuning with my car with HP tuners lately, and when I have ASP underdrive pulley. My battery keeps going dead when running ac, radio, and doing my tuning. I'm thinking about getting alternator Overdrive pulley. Does this reduce hp at all? Will it help my car charge battery better? Any suggestions would be great guys thank you all.

 

The overdrive pulley will bring your charging rpm almost back to factory. It will eliminate the hp gains from the underdrive crank pulley to the alternator only.

You should probably not buy the overdrive and just use caution with your ac/radio, while tunning, or in heavy traffic situations. If you get in a traffic jam use a lower fan setting or turn the ac off if your idle is so slow that it is not charging. If you are tuning with the engine off then you need a charger on the battery during this time. I don't understand why the battery is going dead if the engine is running.

If you ever lose a tight race then you will wish you had the larger factory alternator pulley. It also protects your alternator from over spinning at 6000+ rpm.

 

Right now I am running factory alternator pulley. Did not put the Underdrive one on. I reallly hope I don't have some kidn of electrical problem. Everything was fine before I changed the crank balancer to the underdrive.

 

Undercharging during heavy electrical loads is very common with under drive crank pulleys in automatic transmission cars. They idle too slow.
There are but 3 cures:
loose the UD crank pulley
overdrive the alternator
or consiously lessen the load on the charging system.

 

Right Al I'm thinking about goign the overdrive route, only $20 for the pulley. Will I lose any hp by doing this? Are there any downsides?

How come when I floor the car, it stops charging the battery until I go back to cruise? Is this normal?

 

A tiny little bit.

 

cool al thanks again. Looks like I'll order with my timing chain.