Nagase

iTrader: (6)

Was browsing and saw that RS Aziawa sells a 1 kg lighter but stock output alternator.

Losing some weight off the nose would be great, but I haven't heard of that being done.

eazy_tom

iTrader: (2)

Someone on here? got an alternator made for an "ford hotrod" or something from summit maybe.
He said it was a lot lighter and had sufficient output, he mounted it up using a adjustable heim joint.

Hopefully he will chime in and explain all of this better.

miata2fast

iTrader: (2)

bbundy has a thread where he discusses installing a light alternator. It is something I plan to do as well, eventually.

guttedmiata

Using a mini one wire alternator that just went on this winter but it already just quit charging. Not sure why, but it is fairly close to the twin screw charger and is maybe overheating. Of course maybe it's just junk, not sure. It is a cheaper eBay version which could also be the issue. It definitely saved a few pounds but isn't worth it if it doesn't do the job.

miata2fast

iTrader: (2)

bbundy had issues with his alternator as well. I think he got it worked out.

bbundy

I’m using this one.
http://www.summitracing.com/parts/pwm-8172/overview/
The spec sheet that came with it shows it has a is 61 amp capacity not 50.
The original cheap Ebay one I bought would quit working after a day or two of use replaced it twice but this more expensive name brand one has been working for more than a year.

I found an Unorthodox ribbed aluminum pulley for it on Ebay. I think it was for a Nissan TT300ZX if I remember correctly . But it worked had the right number of ribs and was a slight under drive which calculated would keep the alternate below the max RPM the spec sheet said at a little over 8000 rpm redline. It was also super light in weight compared to the big hunk of steel that comes with the alternator.

I wouldn’t say it has been without issues but I am not sure it’s all the fault of the alternator.

1) The alternator is not wired exactly like stock. The stock alternator has the field coil wired directly to the battery and the circuitry inside the regulator turns it on when it reaches a certain RPM. This one will run your battery down while parked overnight unless you move the field coil wire to a switched power that goes through the key switch somehow.

2) The first time I thought I killed it turned out the connector jumper I had for the two wire plug on it came loose.

3) Second time I thought I killed it turned out the nut on the battery post terminal came loose and fell off.

4) I have had starting issues but I still have the same issues with the stock alternator. I think it may be a combination of a Hydra ECU and ID1000 injectors. Both of which turn into complete ******** and don’t work properly if they are being cheated of voltage while cranking. I think it may be more an issue with the 2.5 lb. 12 cell ballistic battery and long battery cables. Occasionally it will get in a mode where it will crank just fine but won’t start. Lots of sitting and idling will make it much worse. It hates autocross where there is a lot of stopping and starting and idling compared to a minute of actual run time. The little alternator doesn’t run down the battery at idle but it also doesn’t keep it topped off to the full amount above 13 volts unless the engine is running about 1500 rpm. 27 lb. optima yellow top doesn’t have this problem. The combination of the Hydra and the ID1000’s won’t start the car it seems if the hydra thinks it has less than 10 volts. And the hydra thinks it has 10 when you measure 11 at the battery or alternator. Which means you need like 12.7-13 at least at the battery before attempting to start it.

5) Latest issue I’m having is my wideband 02 is wigging out. Signal looks like it has electrical noise on it after melting the cable on the exhaust and trying to repair it. I don’t know if I just screwed up the O2 or the charge system is crating high frequency noise on the O2 signal and no it is not an exhaust leak. Running open loop now till I figure that out.

y8s

iTrader: (8)

are the lightweight alternators wound with aluminum wire? Is it as reliable as copper?

concealer404

iTrader: (3)

So this saves... 2-3lbs?

bbundy

A little over 5 pounds and the heavey rotating bits turn at almost 2.5 time engine RPM and with a smaller diameter so it has a much lower MOI. So the reduction in rotational inertial is significant. the portion of the weight that is rotating is Sort of like dropping 5 lbs off the flywheel.

mr_hyde

iTrader: (4)

Could you add a capacitor on the power going into the Hydra so it doesn't see the voltage drop when the starter cranks and injectors/coils start to fire?

Leafy

iTrader: (1)

I've been looking as well. There are some interesting choices in the forklift and airplane engines.

Raucky

iTrader: (1)

I noticed that Powermaster makes a 75 amp mini just like your "50 amp". I'm not worried about the price difference keep in mind. Will that one work better and I'm assuming it prob weighs a little more, but maybe not?

Would you change your alternators again if you had to do it over for 5lbs saved?

Leafy

iTrader: (1)

Back from the dead. Thanks to one of out mazda sedan based cousins I found the secret sauce. 5.7lb alternator that bolts right in and just needs a simple re-wire of a plug avalaible on ebay. 95-97 geo metro 3 cylinder or 89-97 geo tracker 1.6. You want the denso one not the mitsu one because the mitsu one sucks. Stock its 55 amp, there's a company that sells them rebuilt to 75amps though. The 89-94 metro 3 cylinder alternator uses a 3 rib pulley so it wont work. Oh yeah the electrical connector. And the wiring diagram.

Disclaimer, no one has ever done this before on a miata that I could find. But the 3 rib pulley version works fine on the 3 rib belt mazda motors, and the 4 rib mazda versions of our alternator work on their 4 rib versions. So I dont see how this couldnt work. This alternator uses the same guts and front cover as the one bundy posted but its slightly heavier because it has the rear mount to go directly onto out motors.

concealer404

iTrader: (3)

I swear i posted that on here in the last 6 months, but the Swift GT should also work and not be such a ridiculous rating hit in terms of amps.

Or maybe i posted it in the thread that you found that info.

Leafy

iTrader: (1)

No, it was Gavin's build thread. I was reading it... because reasons.

I cannot find a Denso swift gt alternator, and all the re-man ones are 50-55amp anyways. There's one from a geo tracker in a junk yard 6 miles from my house for $30. I know what I'm doing this weekend after I put the lifters and cams back in the motor.

zossy1

iTrader: (4)

How much lighter are these than a standard 60 amp NA6 alternator?

Any idea what the shaft diameter is? This is looking like a promising find, provided I can underdrive it.

Leafy

iTrader: (1)

The shaft diameter is smaller than the 1.8 alternators for sure. I suspect its the same as the racing ones, like bobs. Whats the weight on the NA6 alternators with the stupid v belt pulley? These are just under 6 pounds.

zossy1

iTrader: (4)

I have one at home, will put it on the scales when I get home from work.

bbundy

After multiple failures of the tiny alternators and constantly having issues with running the battery down while idling I tried going back to stock. I didn’t have a good stock one so I bought a new and traded in my stock original one. The new replacement stock alternator failed within in a few weeks as well.

I ended up finding a suzuki swift alternator rated at 60 amps for a replacement again and it has been working fine for a season. It’s probably the same basic guts, housing, and regulator as in the RS Aziawa unit but cost more like $100 instead of $765 its about 4 lbs lighter than stock Miata most of the weight is rotating bits that spin at 2.5X engine rpm.

Down on the page there is a 60 amp one. Took a bit of custom mounting and connector wiring but not too difficult.

Suzuki Swift Alternator - Car Alternators - USA Industries Bosch Pure Energy Denso Remy - 2001 1994 01 94 - PartsGeek.com

mr_hyde

iTrader: (4)

I went through two failed FLAPS NA8 units before the third one worked. They all seemed fine out of the box but crapped on the track. I don't think the voltage regular can take sustained 7k rpm on track but the same units probably would have been fine in a grocery getter.