A friend just swapped an LT1 out of a 95Z into his 89 IROC. It is being run with DFI V.6. Every alternator we put on gets burned out after a couple times started. The alternators being used are stock LT1 alternators. For those who have performed an LT1 swap, what alternator style are you using, and did you have this problem? We suspect it has something to do with the fact that the LT1 is a 1wire alternator, and the TPI style one is a 2 wire. We have a couple hypothesis' about this, but i wanted to hear what everyone else though. Thanks Edit- forgot to mention, we are using the LT1 alternator plug, and have the single wire connected to the instrument cluster

never had a problem with the alternator except it broke (post for the batt wire fell out), I am using an older alt. with the original wires.
I have heard alot of good things about tuff stuff alternators if you want to give that a try though

You're using an older alternator? Like, TPI style alternator? I haven't seen this directly, but my friend says the TPI style alternator won't fit onto the brackers

LT1 Style alternator use 2 wires, 1 power source from ignition , 1 power feed from battery. the large wire should go to the starter solenoid battery feed, the smalL one is the ignition.

if plugged the other way around, the alternator will only charge after waiting a while once the car is started.

You are blowing alternator for 3 possible reasons .

1. you're using alternator way too small and the power consumption of your 3rd gen is way higher. LT1 have 110 amps alternator to my knowledge.

2. it's plugged incorrectly. or bad connections, corrosion.

3. the wire that goes back to the battery for charging it is connected on the battery it self or near it, it needs to be plugged somewhere else on your wiring harness, for example: ceramic positive distribution born in front of the battery tray.

LT1 alt is a 140 amp unit

The small red wire that goes to the alternator is actually just for the light. I junked two alternators before I found this out. It should be hooked to 12 volts, but have a bulb or a resistor in between. All you did to the alternators is burn the regulator. You can replace that, and they will be fine.
Todd

Oh, yeah. The small red wire has to be hooked up to work. I just wired it to 12 volts with the resistor, but don't remember the resistor value. Take a peanut bulb (94) I think and measure the resistance. Then, just put that in the wire and you'll be just fine.
Todd

Todd, if using the LT1 harness I don't see why he needs to add a resistence or a "light" on the red wire.

todd, I remember doing something like that to mine just after the swap too because I went though about 5 alternators within a year. in the end, it turned out that the resistors didnt work, but for some reason I havent burned up any more alternators.

The way I understood it, the small red wire needs to show a voltage to start the alternator charging. I used this website as a reference: http://www.alternatorparts.com/ I couldn't find the exact page that I went by, but there is a diagram on the site somewhere.
Correct me if I'm wrong.

TexasLT1 -- What did you end up doing to solve your alt. problem?


Thanks,
Todd