You can go for a LONG time on a good battery. I had a crappy battery in my STE and I went from my house to the dragstrip (70 miles), made 6 runs, shutting the car off between each run, and drove the car to the gas station 5 miles from the dragstrip and filled up then started it back up. And drove home with the lights on, windshield wipers on (it was raining pretty good). I got 8 miles from home before the car finally died. So ~150 miles and ~8 starts with no alt. on a crappy battery (IIRC it was only like 500CA to begin with and it was on its way out at the time too), running the lights, radio, wipers. Needless to say, you're not gonna have a problem if you only have it off for a mile or two.

Shawn

Would you need a relay, or just a switch? I need to know which wire to tap on the alternator. A diagram or picture would be a huge help.

I like the idea...ZZP is selling some overdrive pulley for the serieII, I guess it'* about the same effect, exept you shut it off completly instead of partially with the pulley... It would also be cheaper but for track use only but I guess you'll see more gain...

All you really need is a switch and some wire. I will try to get pics, but it will probably be a while. Its not the wire that bolts on to the alternator, its the one that plugs in with the clip. There should be a few wires coming off of it, all you have to do is cut off the ground or the power going to it. (ground would be easier because it would only require 1 wire instead of two because for the positive you would have to run a wire to and from the switch, with the ground you just ground it under the dash or something and then run one wire under the hood) I can probably get you a wiring diagram on Monday if I remember if that will help.

Shawn

GM has something like this. It is a clutch pulley on the ALT. I think after 3,000 RPM it disengages the ALT.

This ides I like. Would you have a part #?

I cant remember what it was on. . . . . .But I think it was on a new pontiac. OR maybe it was on LS2 stuff? I'll ask Ryan, he will remember.

Running off the battery can reduce spark voltage to a degree. This really needs to be tested.

Retrofitting to a clutch on the alt would be nearly impossible. It'll push your belt path out too far.

or you would have to design a new alt mount and god knows what else. If we turn it off electrically it will run just like if it had a clutch on it. If we can get this worked out we have some serious power waiting to be harnessed. Do we have any physics people out there who can figure out how much power a 160 amp alt takes to run? On 14v it takes about 2240Watts.

According to my calculations, if your alternator was actually supplying 160 amps (which it isn't most of the time), it would require 3hp to do so.....this doesn't take into account parasitic drag or efficiency of the alternator. Perhaps assume a 5hp gain by doing this. Just a guess based on some calculations.

2240 W = 3.003889 hp