2nd gen FD alternator install
The stock alternators are pretty weak. Between 60-80 amps depending on your year/model. They are fine for stock cars. But add an electric fan, stereo, ign box. or all 3, and it starts to get taxed. With my heater, headlights, e-fan, stereo, and foot on the brake. I was seeing 11.7-12V at idle. Not good.
I am not aware of anyone that makes a bolt in upgraded alternator. And I did search. Some local alternator shops could probably rebuild them with higher ratings. but I hear so many bad things about rebuilt and remained alternators I really didn't want one..
The closest thing that fits is the 3rd gen (93-95 rx7) alternator with minor differences. It's rated at 100amps but people claim its more like 120. And they are really well made. unlike other parts of the 3rd gen :) Stock used units should be found for fairly cheap.
There are a couple of minor differences between them. The biggest one is the pulley. The FC uses a v-belt pulley where as the FD is serpentine. The FC pulley doesn't fit onto the FD once because the FD has a bigger shaft, so the hole in the middle of the FC pulley is smaller. Some people drill the hole biger and it fits fine. The other way is to find a different pulley that fits. I matched up an early 60's-70's GM pulley and it fits perfect. I took it to a local alternator shop and they found it.
The 2nd difference is the ear on the driver side of the alt is threaded on the FC alt, but is just a hole on the FD one. So you need to get a longer bolt with a nut that fits. I used an 8mm one.
the 3rd is the wiring. the 89-91 alts have the exact same plug (show below) just in a different spot. no problem. but the 86-88 have a different plug. You need to cut the 2 wires going to the plug and either find the right plug to attach them too. or some people just put spade connecters on each wire and stick them on the alt. Since I have an 89 I didn't have to deal with that acording to another site "the black wire routes to the UPPER plug on the FD alternator."
FD alt compared to FC (FD with red pulley) FD is slighter bigger.
To remove the Alt there are 4 things. 2 bolts (arrows), the plug (on the back), and the main power wire held on by a nut (blue dot). lossen both bolts and push down on the alt to lossen the belt and slip if off. take the wireing off. then yank up on the alt.
it's out! (note water temp gauge sender in water pump housing)
The one problem I had getting it in was this. I could not get the alt down very far as it was hitting part of the stock wiring harness as the FD alt sticks father backwards. I couldn't get it down far enough to get the belt back on... finaly after struging a bit (with both bolts removed from the alt and it pushed down as far as I wanted without to many crunching noises from the harness) I manged to get it part way on and finish it by turning the pulley with a rachet. (like putting a bike chain back on..) I probably could have goten a slighten longer belt to make it easy. but it wouldn't have worked as you'll see at the bottom.
Alternator installed and connected.
You can see the new bolt / nut used. It was slightly too long and hitting that metal bracket so I had to use a couple washers to space it back out. The other bolt I had bought was slightly to short...
ouch... I have about 1mm of clearance to the strut bar now!. hope the belt doesn't strech :)
Hmm not as much inprovement as I had hoped for. but I did have the best FC one (80amp). 86-88 whould improve more. But we'll see later. only drove for 20 mins so far. it's up to 12.5-13v now at idle with everything turned on.
The other thing I've noticed with both though is after 10-15 mins I lose around 0.5v. I think it's from the heat. (you can't even touch the alt its hot! as is everything under the hood) getting rid of the under hood temps better would raise the voltage I think!. we'll see when I get my reverse hood vent in the near future :)