Mechman 140A Alternator for my 242

[dbarton]

I bought a new Mechman 140A alternator for my 242. This originated from ILLINTENT and BADVLVO's charging system thread here: http://forums.turbobricks.com/showthread.php?t=213215

The reason I bought this is three-fold.
1. I'm using a lot of juice in my 242 and the 100A Bosch unit is barely hanging on.
2. The Bosch unit really doesn't do well at idle, especially when running AC with big pusher and puller fans. The puller fan I'm currently using is at the bottom of this page: http://www.davebarton.com/ElectricCoolingFans.html. It pulls close to 40A at full speed.
3. The Bosch unit suffers pretty bad when it gets heat soaked and the difference between cold and hot voltage under heavy loads can be from 14v to 12v. Yup, a full 2 volt drop.

Illintent has assured me that the large case 140A unit I bought will have excellent output at idle and will cool lots better than the Bosch unit.

So let's see....

Here's the Mechman unit next to my Bosch 100A unit. Illintent provided some spacers to make it simple to mount it in my normal 240 lower-right spot.

I ended up using the stock adjuster bracket you'll see in later pics. But I flipped it over to compensate for the fatter mount point on the GM alt. Surprisingly, it fit pretty well.

Here ya go... installed.

Here you can see the back spacer.
And since there's no place on the case to attach a ground cable, I did it this way.

BELTS: The stock belts are 10x925 mm. This alt requires larger belts because it will not swing toward the motor as much as a Bosch. I used 10x965 mm belts and it was a perfect fit.

 

[dbarton]

COLD TESTING:

Initial cold start, 65 deg F ambient, no load, at idle, measured at battery.
14.40 to 14.45v

AC on, fan on 3. This brings the big puller fan to 50% and the pusher/condenser fan to 20% initially.
14.05 to 14.10v

AC on, fan on 3, headlights on.
13.95v

AC on, fan on 3, headlights on bright.
13.90v

These results are really not remarkable. My 100A Bosch would do this well cold. The REAL test will be in hot weather. The weather is supposed to get hot later in the week. More testing to come.

 

[Group A]

What was the weight difference?
Nice write up so far Dave.

 

[Texas240]

whats the serial number on the alternator??

 

[klr142]

Thanks Dave. Looking forward to the hot results, even though I'm not really having charging problems I am wanting to do this at some point. This spins a bit better than stock too, right?

Also, does this one have all the other hook-ups, one for the green/signal wire to the light in the dash, etc.?

EDIT: Also, does it seem quieter at higher rpm than the Bosch you had in there?

 

[dbarton]

What was the weight difference?
Nice write up so far Dave.

Didn't think to weigh it, but it felt about the same as the big Bosch. Maybe heavier.

whats the serial number on the alternator??

What??

Also, does this one have all the other hook-ups, one for the green/signal wire to the light in the dash, etc.? Also, does it seem quieter at higher rpm than the Bosch you had in there?

Fat B+
D+ for dash light
Ground
That's all

Quieter at high rpm? I suppose if I could tune out the engine, then I could hear the alternator??

 

[HonestJhon]

I grounded mine the same way. LOL!

And I have the same alt. I think. It is a really good unit.I've never checked voltages at the battery with all my lights running. 4 hellas. Both headlights and the fans running. But the gauge I have hooked up never drops below 12 with all that junk running at the same time. And its hooked reading voltage off the cig lighter.

 

[doucheNozzle]

Nice write up. Curious to see the full results.

 

[dbarton]

I grounded mine the same way. LOL! And I have the same alt. I think. It is a really good unit.I've never checked voltages at the battery with all my lights running.

Is you alternator in the lower right, ala 240, or in the upper left, ala 740? Turbo or non?

 

[badvlvo]

Nice pics Dave. He set you up with the later case with the internal fans.

Did you install a 4ga wire from Alt+ to Batt+?

13.9v with everything on is pretty good for any alternator that size at that engine speed.

 

[klr142]

Quieter at high rpm? I suppose if I could tune out the engine, then I could hear the alternator??

My engine just seems very noisy/whiny and a decent amount of it seems to come from the alternator, even though it's been replaced in the past year(reman Bosch 80A). I wonder if the fan design on the new one is quieter than the external setup, and the new bearings may be quieter as well?

 

[dbarton]

Did you install a 4ga wire from Alt+ to Batt+?

No. I'll do that AFTER testing. I want to see how it does with the same hook ups my Bosch had.

13.9v with everything on is pretty good for any alternator that size at that engine speed.

Remember that's COLD. A hot alternator is a whole different animal.

My engine just seems very noisy/whiny and a decent amount of it seems to come from the alternator, even though it's been replaced in the past year(reman Bosch 80A). I wonder if the fan design on the new one is quieter than the external setup, and the new bearings may be quieter as well?

I have never noticed a Bosch external fan being noisy, unless it's broken. If bearings can be heard at any time, I would thing they would be very shot.

 

[klr142]

I have never noticed a Bosch external fan being noisy, unless it's broken. If bearings can be heard at any time, I would thing they would be very shot.

I may just be anal, but at the same time there is something odd about it... The metal plate that goes in between the pulley and the fan portion of attachments broke around the center and was rattling previously. I just removed it so it looks a little funny, but should operate the same. Who knows.

 

[dbarton]

WARM TESTING: (Hot-hot testing still to come)

Ok, tested today with 90 deg F ambient. Took the car for a 10 minute drive with the AC on.
Parked and found the following:

AC on, fan on 3. Nothing else. Pusher/puller fans were running higher simply because they're variable and they do that when engine is warm.
13.30 to 13.40v (compare this to cold testing of 14.05v)

Measured alternator surface temp.
Top front (case): 170 deg F
Top rear (case): 190 deg F
Top rear plastic cover: 240 deg F

 

[dbarton]

Regarding keeping an alternator cool, I had an idea. Right now I'm not running a belly pan, but when I put it back on, I think fabbing a scoop and duct pointing up at the alternator would be a worthwhile idea.

Anyone tried this?
Dave

 

[FunkyStankyChicken]

e36 m3 has alt ducting, cant be a bad idea.

 

[Texas240]

I mean, brand and serial number. Thinking of picking one up but dont want to spend the money for what you got. blabla

 

[dbarton]

I mean, brand and serial number. Thinking of picking one up but dont want to spend the money for what you got. blabla

Brand: Mechman
More: http://forums.turbobricks.com/showthread.php?t=213215
That's all I know about it.

 

[HonestJhon]

Mine is on mu 940 Turbo. So in upper drivers side.

 

[dbarton]

Mine is on mu 940 Turbo. So in upper drivers side.

The temp your alternator sees is a lot less then and it won't bleed as much voltage when hot. My alternator so far is seeing about 190 to 240 deg F. Yours will not likely see higher than 140 (educated guess).
Dave