The stock one in my s4 is getting old and I'm thinking about upgrading. Which alternator do you guys prefer? Remember my budget is tight so a good deal would be much appreciated. I'm also thinking about adding a banging sound system, lol.

 

the easy conversion is a FD alternator that puts out about 100 amps.
The Taurus alternator is in a write up on here too,and that is another alternative.
Power Bastards also offer a Hi Output Alt.

 

Thanks Styx!

 

130 Amp Taurus Alternator wins every time. $20 at your local junkyard plus the cost of the FD Alt retrofit pulley from Mazdatrix will mean a permanent solution to charging. It is also the only one I'd suggest using if you are considering an E-fan. I tried a FD alternator coupled with a 2-speed Taurus fan, and the FD Alt just couldn't keep up. Swapped in the Taurus Alt and it was awesome!

See my gallery for proper wiring information. It requires some simple fabrication in the manner of two flat brackets and some washers for proper pulley alignment, but uses the same pulley as a FD Alt retrofit. On my 20B FC, all I did was use two leftover pieces of 1/4" thick hardware store steel and drill two 5/16" holes about 1" apart (measured center-to-center). Measurements don't have to be exact as long as the bolts can go through, but the brackets do have to match and fit flush against the water pump housing. These go on the passenger side mounting point with five M8 washers as shown below:

Rear bracket---WP housing---stock spacer---5x washers---front bracket

While not exactly pretty, this will place the alternator in the correct alignment. As for the driver's side mount, the adjustment strap will need flipped over and four M6 washers placed between the alternator and strap.

The output stud is a bit short on the Taurus Alternator and it is near the bottom of the case when mounted on the FC. What I did to remedy this was to get 3 coupling nuts and some M6x1.0 threaded rod to make an extension for it. Adding 2-3 layers of heat shrink to the extension should protect sufficiently well against any possible shorting.

It's a pain to get the old belt back on because the new alternator sits slightly higher than the original one did. Simplest way I know is to bolt everything together loosely, then get the belt roughly in place on the outer groove of the pulley (passenger side of the pulley). Now turn the engine over in the correct direction with a ratchet (using your right hand) while pushing the belt into the groove with your left thumb. It will go right in, just like how the chain on a 10-speed bike switches gears via its Derailleur.

Now repeat the process in the same derailleur action as before to get the belt in the rear groove. If using dual belts, repeat once more for the second belt. Tighten everything to spec and you're done.

This might sound a bit like overkill, but it would be a very smart idea to replace ALL of the main Power & Ground cables when doing the alternator upgrade, along with the battery terminals. It's a bit annoying to extract the cables from the Engine Harness, but will be well worth the effort to run some good 4awg welding cable down to the starter. 48" for Battery positive to Starter, 24" for Battery negative to Main Ground and 24" for Main Ground to Starter Ground. 24" Should be sufficient for Alternator to Battery Positive as well. Follow this guide to the letter, using cable and lugs from a welding supply store and you will have fantastic results:
Proper RX-7 Grounding Procedures

$5 on Marine Battery Terminals is money well spent and combined with the cabling upgrades, will make your car start easier, run better and be more reliable. The reason for this is because there are now 3 cables on the positive terminal (Fuse box, Alternator & Starter) and regular terminals tend to have difficulty in such situations.

 

Awesome reply, very helpful! I think I'll go with the taurus alt since its cheaper and stronger. Is there a specific model of the Taurus I should look for at the yards?

 

One question always trouble me with the alternator upgrade...

Would the front strut bar still fit? I remember reading somewhere that both the FD and Taurus alternators are bigger than the stock FC one.

 

Good question. I would like to know this as well

 

Link to the alternator modifications?

 

The Dodge Avenger application is interesting, direct bolt on same harness, except needs an external regulator?

 

I have the S6 alt with one of those taurus fans and it works ok... I had to change to a large 120amp starter solenoid though, seemed to iron things out.