I have a 87 rx7 turbo 2, can i use a 89-91 alterator in my car(because of the higher amperage)?

 

yes, have to change the pully

 

dont you also have to buy a s5 plug?

 

yes, or just make an adapter I was think FD>FC alt upgrade which is the best solution

 

You can put a 89plus on a 86/87. No pulley change needed. It's a direct fit. The small electrical plug IS different. The electrical plugs are not near the same....BUT...it's still a two wire circuit. It's mearly a matter of making a simple jumper b/t the stock plug and the new alternators jack. NOT a big deal at all. It's only a big deal if you get the wrong wire in the wrong place, and even then that is easily overcome by inserting a blocking diode in one of the wires to replace the one you might have blown in the alternator. Cost would be about a buck fifty and a trip to the RadioShack. So go out there and hit a home run and buy that 89 plus alternator. Talking series five on a series four only.

 

what about 93 alt on 87 possible?

 

Yes, Many people (including me) are running the FD alt. There is a thead in the archives about it.

 

i did that too
well my old alt was dead thats why i had to do it

 

That is incorrect... you only have to change the plug.

You would have to change the pully if using a 93+ alt on there, but not a 89-91 alt.