As many of you may know, the S4 alternator is a pathetic little device with a VERY low output. I was under the impression that any decent alternator shop could re-wire it for a higher output. I wanted it that way in order to maintain a stock appearance. Apparently nobody re-wires these type alternators. Anyone know if there is a place that does this?

I know that many people here have done other things, like put the S5 alternator in. What is the AMP rating for the S5 alternator? I also know that someone here is running a 200 amp alternator, but I lost the link and cant find the thread...

I need to get a solution to this problem soon, due to the monsoons here in Tucson, I sometimes have to drive with my lights, wipers, A/C, and cooling fans. Last time my running volts dropped to 8v at idle!

What have all of you done?

Rat

 

Put a 2 guage wire between the postive post and the alternator output terminal in parallell with the stock 10 guage wire, and you will notice a huge difference in voltage..Max

 

Lets not and say we did


I would check some online parts stores are get some amperage ratings .. there is ALOT of altinators with a similar design to the RX ones for other cars. I am sure you can get one from another car to work .. all you need to do is get a belt to spin it. You might have to do some minor facrication but in general most altinators are very similar in design ... and if you figure somthing out let us all know .. my lights dim when my music is loud (1200 watts)

Also you might want to consider a higher amprage battery .. a good battery should never drop near 8 volts even with a weak alt.

 

Dude i'm on the same boat. and soon i would like to have an amp with a single sub. having the crank pulley doesn't help my situation. We need ANSWERS

 

What does that do? Decrease the resistance of the original wire?

 

I just bought an Optima Red Top about 4 hours ago. I just got to get outta work so I can install it. I get them here on base for 99.95 and NO TAX!! I love the military.

Is that a good enough battery?

And thats what I am trying to find out, what have other people done. I want to have to make minimal mods. There used to be a thread on putting the S5 into the S4, I think that Rx7Impreza (justin) did it.

 

Amen brother!

 

I've got a bosch replacement, it gets like 75 amps. And it works like a charm, i just got it rebuilt the other day, no problems since :P

 

Is this the one?

https://www.rx7club.com/forum/showth...hreadid=110075

I'm looking to beef things up, too. But I don't want to go screwing around chasing after belt and pulley sizes.

I've read about running a wire from the pos to the alt on a couple of 7 sites, but when I asked around about it about 50% of the feedback was 'you may fry your system.' So I didn't do it...

 

ya I kinda need a bigger one now I think... S5 one + redtop drops to 12.4 or so at idle now with e-fan and lights on. (and crane ign box, rewired fd fuel pump, 2 amps etc ) it should never get lower then 12, that means your battery sucks. if I hold it at 2000rpm it goes back up to 13.6 or so. and driving is 13.5+

that's all reading off the turbo timmer so it's probbaly a tad higher at the alternator.

 

Thats not the exact one, but that is an EXCELLENT thread. I believe that RX7Impreza did a write up on putting either the S5 or the FD alternator into the S4. Thats the one I was looking for. I am gonna keep trying to find it.

 

So wich alternator is better? The S5 or the FD?

 

https://www.rx7club.com/forum/showth...ght=Alternator

Here is a post about putting the FD alt in the FC. Looks like its the route I am gonna go. I just wonder where they got the new pulley.

Rat

 

https://www.rx7club.com/forum/showth...85#post1021285

Here is the one that RX-7impreza did. Although I think that I am gonna go with the FD alternator. Just need to figure out were to get a pulley.

 

I think the s5 is 80 amps and the FD is 100. the s4 is 60 or 70 I think.

 

yeah, I got 70 amps for S4, 80 amps for S5 and 100 amps for FD. Only hitch with putting the FD into the FC is that you need a pully. The s4/s5 pully wont fit onto the FD shaft. Havent solved that dilemma yet. i am gonna start pricing the FD alternators.

 

oops..

 

I have a 70 amp S4 alternator and it sits on 14.5-14.7 volts all day long. I have no a/c, no heater, not this that and the other thing hahaha.

 

I've upgraded to a S5 Alternator as well as added an 8 Gauge wire. Awhile cruising, my volts have shot up by 1.5. With so many additional electrical goodies wired up to my Battery, I am once again considering upgrading my Alternator to that of a FD.

 

ive got a bit of a problem with my alternator,my old one was burned up(pd failure)along with the butt connector,so i just cut it off where the wire wasnt burned.how can i reconnect my alternator to my power harness with no butt connector?

 

Go to a car audio shop, and see what sort of alternatives they can offer... Particularly Optima stuff.

 

I'm putting an FD alternator in my 88 this weekend. No big changes except for pulley. I got a dual alt pulley and had it drilled/bored out just a tad bit to get it too fit onto the FD alternator shaft. MikeL just did a writeup on his FD alternator swap in his 88. Good writeup.

 

You will also need the harness clip aswell.

 

incorrect. 2 jumper wires about 6" long, with a male spade connector on one in and a female on the other. male goes into my alternator wiring harness, female connects too the alternator. simple as that. no need for cutting or any of that.

 

2 gauge wire?!?!?!?

8 gauge should be MORE than enough.......