87 alternator

[BLACK Ttype]

Is it possible to run an 87 alternator on our cars if we change the pulley?

 

[cool 84]

No, the 87 unit is a one wire and the 84 is a two wire. Plus the 87 is physically bigger. You might be able to go to the junkyard and get the aluminum bracket that the alternator bolts to off of a NA 3.8L and it would probably physically bolt up but then you have the wiring problem. The brackets between the early turbo cars and NA look identical but the NA are made to accept the 87 style alternator. If you're looking for more amperage, it's pretty cheap (cheaper than a $120 87 alternator) to have a stereo shop or electric shop boost the output during a rebuild.

The 84 alternator is actually a later design and has a larger bearing that's less failure prone not to mention a better cooling fan.

The other thing, I had my car tested with both cooling fans on and every electric component running (bright lights, blowermotor, windshieldwipers, etc) and it only drew ~50 amps.

 

[BLACK Ttype]

cool 84

I already have the bracket off of a NA3.8l w/ an alt from a z28 I beleive. And I could get an 87 alt really cheap. How do I tackle the wiring problem.
The reason I ask is because I was going to build one of these
http://www.gnttype.org/techarea/projects/gnalt.html so I could manualy control the voltage.

PS
The reason for the NA bracket is because the orig. bracket broke like three times and I just kept getting it welded and it kept breaking.

 

[BLACK Ttype]

Anyone good with wiring wanna help me out?
TTT

 

[cool 84]

For some reason your link doesn't work from webtv, I'll have to check it when I'm on a real computer. I'm assuming you are wanting to go with some sort of a volt booster? It can be done with the early alternator too. I read it somewhere years ago and it involves buying a resisitor from Radio Shack and installing it inline with one of the wires on the alt. It obviously won't go on or off according to boost but it will boost your voltage all the time to ~14.5V. Like I said, the hotair alt is a superior piece to the 87 Gn alt.

 

[BLACK Ttype]

That's exactly what I am trying to do.
My alt always runs around 12.9 to 13.0v.
Anyone have ideas for boosting the voltage on the 2 wire alt.?

 

[mybuick]

i used a alternator 200 amp from a 4.9 liter caddilac it bolts right in with no problems.

 

[cool 84]

Originally posted by mybuick
i used a alternator 200 amp from a 4.9 liter caddilac it bolts right in with no problems.

I think the main problem is voltage. 94 amps is plenty for nearly anything you could run on the car. I'm going to start looking around for the info on boosting the voltage. I've been wanting to do that for a couple years and never got around to it. I remember it cost less than $10.

 

[cool 84]

I did a little research and it looks like you put a resistor in the wire that goes from the back of the alternator to the two wire plug. Not that sure because I was looking at diagrams of the 87 alternator. The purpose is to fool the voltage regulator into thinking the voltage is lower than it really is. It compensates by raising the voltage. I "think" the wire I mentioned goes to the internal regulator. Maybe someone with a little more electrical knowledge can help out. The other thing I remember from the old article, is I think you start out around 700ohms but not that sure.

If I had a running car I would put a variable potentiometer and turn the dial slowly and see what happens. If we could figure out which wire to tap into and what resistance to use, we would be a hobbs switch away from having a hotair voltbooster.

 

[6SENSE]

I did a little research and it looks like you put a resistor in the wire that goes from the back of the alternator to the two wire plug. Not that sure because I was looking at diagrams of the 87 alternator. The purpose is to fool the voltage regulator into thinking the voltage is lower than it really is. It compensates by raising the voltage. I "think" the wire I mentioned goes to the internal regulator. Maybe someone with a little more electrical knowledge can help out. The other thing I remember from the old article, is I think you start out around 700ohms but not that sure.

If I had a running car I would put a variable potentiometer and turn the dial slowly and see what happens. If we could figure out which wire to tap into and what resistance to use, we would be a hobbs switch away from having a hotair voltbooster.

Anyone ever go ahead and figure this out? Ive got a NA bracket cleaned up and ready to go and am making last decisions on what alt to get. However I see cool 84's point on the amps vs volts. If my voltage was just bumped up I might be okay with what I currently have. When going to a higher amp alt (like the Impala SS) are you certain to have a substantial boost in voltage?

 

[Jerryl]

I have not figured this out but probably could if I had a junk alternator to play with. Read this as this seems fairly simple ....... Be sure to go donw to "modifications"