1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

need alternator more amps help

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Old Oct 28, 2004 | 03:40 PM
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need alternator more amps help

i have an electric fan that i put instead of that power robbing fan clutch. the problem is that it draws too much current. i need an alternator that produces more current any suggestions???
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Old Oct 28, 2004 | 03:50 PM
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You can get an S4 (1986-1988) Turbo alt from a 2nd gen they are 70 amps. They will fit physically and electrically. The one you have is probably 50-60 amp depending on the year that you have (the rating should be on the side of the alt somewhere). If you are willing to do some small modifications, you can get an S5 (1989-1991) alt either turbo or NA, they are 80 amp (this is what I currently have) or you can use a 3rd gen alt (100 amp).

Both the S5 and 3rd gen require a slight change in wiring (they have different regulators than the earlier cars), but will fit physically. The 3rd gen will also require changing of the pulley since the 3rd gen uses a sepentine belt instead of the v-belts.

If you have a '79, it will require a bit more wiring for any of these alts because the '79 had an external regulator while all other 7s had internal regulators.

Kent
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Old Oct 28, 2004 | 07:17 PM
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Dude.

https://www.rx7club.com/showthread.p...ght=alternator
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Old Oct 28, 2004 | 07:44 PM
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The writeup by mar3 is a good one, but you need to be careful. The way that he has it wired will work, but it will cause a drain on the battery when the car is off. Many people have made this mistake. There is alot about it on this site as well as teamfc3s. The problem is the difference in the regulators between the S4 and earlier and the S5 and later. The earlier ones (ours) are an L/R style while the S5 and up are L/S.

The difference is that ours has:
- Output to battery
- L terminal --> idiot light
- R terminal --> switched ignition

The S5 and up:
- Output to battery
- L terminal --> idiot light
- S terminal --> constant power

The S5 style expects to have voltage on the S terminal at all times (even with car off) so if you hook it to a switched source, the regulator is trying to figure out why the voltage is going to zero all of a sudden when the car is turned off. The regulator trys to increase its output, but can't since the car is off. This causes a drain of around 1 amp when the car is off. The car will still charge fine, but if you don't start the car within a few days, you will have a dead battery.

So connect as mar3 said, but the wire that goes to the top part of the old plug (BW) needs to go to constant power (can just connect to the alt output post). I found that I could use the stock spacer instead of the washers, but I have an SE so it may be different on the 12A cars.

That said, I used an S5 turbo (80 amp) alternator and I love it. I don't have an e-fan, amp, or anything like that, but the S5 alt puts out a nice steady voltage. With the stock alt, the voltage would drop with the lights, blower, etc. being on, but it now stays nice and steady. My old alt was on its way out, so I decided to upgrade in the process.

Kent
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