Cummins 4BT & Diesel Conversions Forums banner

1 - 14 of 14 Posts

·
Registered
Joined
·
25 Posts
Discussion Starter #1
I'm working on getting things listed I need to do for a swap so I know what I am looking at pocket book wise. Right now I am running a Delco 12SI alt, with a 15SI 200amp stator and HD internals. The 12si is about 6-6.5"s in diameter.

Is there room for this guy to fit? Right now I am running it on my Ford six as it bolts in place of the stock catch on fire alternator.


And since we're already talking about this, I didn't see anything as to if people were running high amp alts. Is there any threads related to this?
 

·
Registered
Joined
·
329 Posts
I run a 21si with 240 amp and low speed turn on. I couldnt find the appropriate bracketry (cummins) at the time so one was fabbed. It can be done.

I like the fact it has cheap parts as it is getting into the industrial side of things.
 

·
Registered
Joined
·
3,391 Posts
Say, Moose, give the guys a break: how about posting what make/model this is supposed to fit in, and what engine? That makes it much easier to answer the question ;)
 

·
Registered
Joined
·
500 Posts
Unless you're winching or offroading with a ton of lights, why such a large alternator? Big stereo? OB Welder? Ever considered running dual alts?
 

·
Registered
Joined
·
1,203 Posts
Unless you're winching or offroading with a ton of lights, why such a large alternator? Big stereo? OB Welder? Ever considered running dual alts?
wouldn't dual alternators be even harder to fit?

it seems that fitting a bigger alternator would be no big deal especially if you can cut and weld steel...
 

·
Registered
Joined
·
25 Posts
Discussion Starter #7
Say, Moose, give the guys a break: how about posting what make/model this is supposed to fit in, and what engine? That makes it much easier to answer the question ;)
I was only worried about it fitting the motor, I didn't know how close the bracket is to th engine, thinking maybe the possibilty of the case hitting the engine.

Unless you're winching or offroading with a ton of lights, why such a large alternator? Big stereo? OB Welder? Ever considered running dual alts?
Orginally I built the alt because I was plowing, I have upgraded headlights that put out more juice on High's, e-fans, and I was planning on running an e-winch. But since have been running a hydro winch, waiting to find a electric-hydro pump for backup situations so I still need the big amp alt.

200 amp 12si wont work as rpm is too low for idle (stop and go traffic)

Which rpm, the engine or the alt. I've never had a prob producing enough juice at 800-1000rpm, with the e-fans on, lights, heater, and plow going up and down. Usually both belts will squeal under heavy amp draw. I haven't pulled out alt/starter tester to see how much it can put out before smoking it.

I did find out I was glad I have a mega fuse between the alt and battery. As the rectifier shorted out in it and blew the 250 amp fuse.
 

·
Registered
Joined
·
41 Posts
"I did find out I was glad I have a mega fuse between the alt and battery. As the rectifier shorted out in it and blew the 250 amp fuse."

I used one of those mega fuse on my 88 Dodge Truck and it was slick. They are worth the time spent IMHO. You can find them at most marine stores.
 

·
Registered
Joined
·
22 Posts
alternators

Jim Miley had quite the Alternator set up on his Bronco.....was ment to generate most of its power at a slower speed as I recall.....

??? looking for more info on his post & parts list myself......

 

·
Registered
Joined
·
390 Posts
I am also using a 22 si that puts out 180 amps. Here is a link of a company that sells the 22 si up to 250 amps http://www.alternatorparts.com/21-22si_dual_rect.htm The brakets can be purchased from cummins to fit the alternator direct with out having to worry about aligning the pulley's..

Check out my website you can see how it is mounted... the brackets aren't that expensive around $250 to $300.. Let me know if you want the part numbers..
 

·
Registered
Joined
·
180 Posts
200 amp 12si wont work as rpm is too low for idle (stop and go traffic)
Cut in on those older high output 12si alternators is around 900 - 1000 rpm. I am not sure how hard you accellerate in stop and go traffic, but I know that I don't shift anywhere under 1500 rpm. If one of those alternators wouldn't work in stop and go traffic on a 4BT, how would they ever work on anything in town in traffic?
 
1 - 14 of 14 Posts
Top