rx7tt95

I've managed to get the alternator into the FD. Took me about four hours of prep and fabrication, cutting the stock brackets etc...so the larger alternator would fit in. It's a 200A unit.

The FD alternator plug is a simple two wire affair, with a positive and a negative that are marked on the lip of the plug, wires are both about 14ga, one is yellow green(-), the other is yellow black (+). The aftermarket alternator has a four wire plug/pigtail with the wires marked SFLP, left to right.

S=red wire (about 12ga wire)
F=brown wire (14ga wire)
L=brown wire (14ga wire)
P=gray wire (14ga wire)

I was told by the alternator shop (Startech) to connect the S and L wires. The FD +/- wires correspond as such
S=(+)
L=(-)

Therefore I hook the red alternator wire up to the positive side of the FD's harness plug. The L/brown wire hooks up to the negative. S to positive L to negative.

I did all this, hooked up the neg battery terminal and nothing blew, no fuses went, etc..good. I start the car and she fires right up. Voltage fluctuates a bit but eventually I'm seeing around 15V on the Power FC. Car is running fine, a/c works, etc...I'm thinking all is good.

Shutting off the car, I go back to double check everything, do some final wiring, tighten bolts, etc. and I touch the alternator. It's quite hot. Hotter than any of the surrounding parts such as the brackets, UIM, and even the thermostat housing. So now I'm thinking a)she runs really hot, hence the large alternator fan or b) I've hooked up something wrong and if I let her run to long the car will spontaneously combust.

I'm most definitely electrically challenged. Any help here would be greatly appreciated!
Michel

rx7tt95

Just a quick update, seems to be working as designed. Puts out a steady 15V at idle and slightly more under acceleration. So for once I must have done something right! As a bonus, the a/c doesn't drop at idle, windows go up and down very quickly, and the car actually seems a bit more responsive and powerful in the top end department. It's a fairly straightfoward mod for those with failing alternators.

potatochobit

iTrader: (1)

OHH? your windows go up and down faster?

R. Gambino

Keep an eye on the battery. That kind of voltage is getting close to boiling off the electrolyte.

rx7tt95

The batteries are dry cells (2 of them).

Yes, the windows would not completely bog down, but would be very slow to go up with the stereo on, a/c blasting. I don't have that issue any more.

Snook

iTrader: (12)

can't you fry the ecu or break headlight bulbs with that kind of voltage?
I thought anything above 14.5 was bad

gotorx7

A story my machanic told me just came to mind...

Most alternators have vents around the pulley which help to circulate air into the alternator.

All good, except if you happen to be spinning the alternater in the reverse direction to how it was designed, you w'ont get the cooling effect.

Shouldn't cost you anything to check, just look at the vanes on your original alternatr, and make sure the ones on the new alternator face the same way.

Good luck!

jimlab

Good call, glad I read through the thread before posting.

Check the direction of pulley rotation from a/the car that alternator was originally intended for, and you'll probably find that you're turning it in the wrong direction, rendering the fan useless.

rx7tt95

I'll check that out tonight...I ran the car all day yesterday and all day today without issue. If I remember correctly though, I could feel the air being pulled past my fingers when I put them ever so close to the fan. Double checking can't hurt!

I now see about 14V at idle with the a/c on, more when the car is rolling/accelerating. Never more than 15.5 and that's only for a second. It seems to settle on 15V. Doesn't the regulator decide how much voltage to put out? If there's demand for 120 amps, it'll deliver it correct? At the cig lighter I have both a radar detector and a wideband 02 plugged in using an adapter. Both show about 13V at idle, 14v while cruising. The PFC is the only device showing 15V.

After I cruised around last night, the alternator wasn't unduly hot. It was definitely hot, but not alarmingly so. When I first started the car, the engine temps hadn't come up past 60C yet which is why everything else was cold. I was just a bit surprised it heated up that quickly.

One other thing I just thought of...if you look at the fan, you'll see it has a front plate. If it's spinning the other way, it'd be pulling air from inside the alternator to the exterior. Maybe it's supposed to be that way? I'll have to call Startech.

This mod was very inexpensive compared to the Mazsport alternator ($500+) or the Stinger. It took a bit of patience and trial fitment, but very little in the way of fabrication/modification to the stock system. It even uses the GReddy belt. You could even get away with a slightly shorter belt. The wideband powers up much more quickly, the car's idle a/f went from 10.5 to 11.1 (yeah, you read right, blame that one on the PFC not relinquishing full idle control) and really feels better overall. No more driveability issues. Really happy with this mod!

rx7tt95

Fan blows air OUT, not in. It seems to pull it from inside the alternator. E-mailing Startech tonight to double check everything.
Michel

rx7tt95

One other comment, the vanes on the fan are straight and go all the way to the shaft.

rx7tt95

Here's a reply from Cliff at Startech on my installation and voltage issues:

"Michel,

Good to hear from you. Seems like the install went fine. To address your concerns:

- Our alternator is made to run in clockwise direction. So is Mazda's alternator. The cooling direction is from rear to front. All seems correct.

-Assuming your batteries are fully charged and hold up under load, there should be no drain caused by the alternator while the car sits overnite. Turn off engine. Close all doors and trunk. Disable light under hood if present. To check for a draw, remove the battery output wire connected to the back of alternator. Put a test light in line....one end on the alternator's output post, the other end to the car's output wire. If the light is lit, there is a drain. It may or may not be caused by the alternator! If the light stays lit, remove the plug from the alternator and check for drain again. If still lit, leave the alternator unplugged and unconnected at the output post. Do the same test light procedure at the negative battery terminal. Disconnect neg. terminal, clip one end to terminal, the other to battery post negative. If lit, drain is present and not related to alternator.

-Unusually hot alternator temp. is caused by alternator output. This is normal unless the batteries are demanding amperage to complete their charge. Once again, charge and load test batteries individually.

What do you mean by "FD" plug?

By the way, 15V is bordering overcharge. Our regulator is set 14.4V-14.6V with no load. As load increases, voltage will drop from this level. Where is 15V being read?

Let me know what you find and I will try to help further.

Cliff/ Startech Inc. "

Does anyone know where the Power FC reads it's voltage from?
Michel

t-von

iTrader: (8)

Wow they didn't waist any time replying to your e-mail. Do you happen to know what vehicle this alternator is originally designed for?

rx7tt95

No, he didn't! Cliff must have still been at the office. Very nice guy! Anyway, it's originally off a V6 Camaro of all vehicles! (Latest model). They reengineer the guts to put out 200 amps. They don't come like that stock