but you dont have an intercooler sitting up there either :P

 

Hey the alternator that came off that dodge is a Nippon-Denso alternator. Its used on a mopar but its from a jap company :P

 

True, but no alternator should ever be taken over 18,000 rpm. Thus, you have to make sure you have the right pulley diameters.

Divide 18,000 by your maximum rpm used to get your ratio. This ratio must then be transferrred over to pulley diameters.... Thus, as an example:

Provided you never rev above 8000 on your rotary: 18,000/8000 = 2.25

If your crank pulley is 4 inches in diameter, you must then find the correct pulley size for the alt to match:
4/x= 2.25
x= 1.78 inches on the alt.

Now, another thing to consider is that a smaller diameter alt pulley will cause the alt to charge less at idle. I imagine that the high redline on stock rotaries is a good part responsible for the poor charging system's on these cars, as the alt simply doesn't spin as fast as normal cars at idle.

 

i dont know if this is relevant, but in case anyone cares: our stock alternators are made by mitsubishi.

 

And now my dumb question:

Is there any point in trying to 'beef up' the FC alternator? There's a shop in town that specializes in automotive electrical work (they have high-end beasts like Ferrraris and Lambos in their shop on a regular basis, which I take to mean that they know what they're doing) and they've suggested that I bring my alt in to see if they can get more amps out of it. What could I expect from doing this?

 

Smaller pulley on alternator=higher alt rpm=charges more at idle. Still waiting for the pulley diameter or side by side pictures to make a judgement call.
18000 rpm is for one specific brand of bearings or alternators. There are alternator bearings out there for 20000rpm or more. Sounds like a powermaster quote: ttp://www.powermastermotorsports.com/Racing/Delco_Late_Style/Power_Pulleys/power_pulleys.html
But, the flipside to this would be cheap alternators that quit at ~14000rpm. This is why the Contour alternator is probably a better deal than the Dodge alternator. I'd be happy with one that wasn't rewound to 200 amps. 120 is plenty.

A bigger issue would be how the alternator is wired. Since the Dodge has a 3000rpm redline, its alternator is designed for max power/efficiency in a very narrow rpm window. The alternator might not be efficient at higher rpms. And if it was pullied to spin slower, would there be a benefit at idle?
I can see why the FD alternator swap sounds better already.

My rx7 doesn't have a poor charging system. Maybe its because I do not have wanna be hids, underframe lighting, or a booming system. Poor alternator performance=cheap alternator. It was designed to do the job. Too bad that Mazda didn't give it any reserve capacity.

Any armature shop, starter/alternator/motor/generator rebuild shop, can upgrade the alternator. Cost might be an issue for the custom made unit. It would be cheaper to just buy a lookalike alternator with a higher rating. I am waiting for mine to die so that I have an excuse for an upgrade.

What did everyone pay for their 190/200/upgraded alternator?

 

All this conversion stuff might be moot - I just came across a shop that does "rewind" the stock alternator up to 135A.

http://www.4alterstart.com/highoutputalternators/

They claim for $199.95, they can rewind the stock unit up to 135A.



-Ted

 

Small tid bit for you.

The unit mentioned above is externally regulated. In the late eighties Chrysler started putting the regulators in their computers. They fail quite often. Rather than replace the computer the aftermarket companies made regulators for the back off the alternator that bypasses the one in the computer. If you decide to do this alternator swap you could save yourself the hassle of mounting and wring a stand alone regulator by purchasing the replacement regulator from a alternator shop.

 

I know this is old, but when raising the amp's of the alt, is the stock wiring gauge not a concern ?

 

I finally got back into the RX club after many years. I am putting together probably my last FC. On this one I decided to go with a Durango alternator 03 5.7. It is also externally regulated so you will need an external regulator to make it work. Just steer away from made in china components. Powermaster recommends using a Mopar performance regulator. I got the alternator mounted but it required a little fabrication on the lower mounting ears. I probably had to grind down 2mm. I am checking clearance with the linkage for OMP removed.