View Full Version : BD Alternator Upgrade???

04-07-2007, 08:15 PM
Is it possible to get a larger amped alternator for my 2.5 w/o going custom?? I've got all the bells and wistles that was offered for my car minus the sunroof (5mt :twisted: well worth the loss) and I'm going to put in a 1300w stereo setup but don't want to kill anything (yes I'll be running a cap.) and don't want dual batteries. I just want an upgraded (more powerful) alternator. Is their one out their???

04-08-2007, 05:24 PM
I dont know if anybody makes a HO alternator "off the shelf" but you should try asking a couple GOOD auto parts stores if anybody in your area re-builds alternators to spec. I know there are a couple shops in the area here that will build what you want (may need to provide a "core")

04-08-2007, 06:43 PM
You could also get a Yellow Top battery by Optima Batteries. I have one and they are simply amazing!

http://www.optimabatteries.com/publish/ ... otive.html (http://www.optimabatteries.com/publish/optima/americas0/en/config/product_info/automotive.html)

04-09-2007, 12:05 AM
I've killed two Optima's in less than 4 years (2 years apiece) and will NEVER get another one. I'll be getting a Napa dry cell next week to replace my LAST Optima I bought in November 2005.

04-09-2007, 12:28 AM
Battery is just a bandaid to your power problem. Get the higher spec alternator.

04-09-2007, 12:35 AM
Battery is just a bandaid to your power problem. Get the higher spec alternator. What part #????? That's what I'm trying to do, get a higher spec one than I've got.

05-11-2007, 02:52 AM
I might have one. I will let you know. :grin:

05-14-2007, 10:22 AM
Talk to these guys...


05-14-2007, 11:27 AM
I think 05+ legacy/outback alternators are like 110-130 Amps, and should probably fit, but I don't know if its enough for you.

05-14-2007, 11:41 AM
I've killed two Optima's in less than 4 years (2 years apiece) and will NEVER get another one. I'll be getting a Napa dry cell next week to replace my LAST Optima I bought in November 2005.

I've killed a Red top with no stereo, about a year old, but at least warranty covered it, it was however a pain in the ass to get it.

05-14-2007, 12:06 PM
I looked into getting one awhile back and it is not cheap, like $750. I can call the store I was going through and see if he can find it again and get the specs for you.

The stock one is like 75 or 95 amps and should be enought from what I have been told. Def. get a deep cycle battery.

05-14-2007, 12:51 PM
Legacy=85 amps
impreza=75 amps

05-14-2007, 02:25 PM
Def. get a deep cycle battery.


Optima Red tops are not deep cycle. Only the yellow top is.

People assume all optimas are deep cycle.

05-14-2007, 02:31 PM
I would put the system in your car with the stock alternator and get a deep cycle battery with a good CA and see how things go. If you experiance issues you may need to get another cap or a cap battery or the alternator.

05-14-2007, 06:32 PM
I just got done talking to the guys at the local stereo shop and he said that a Kinetik battery is the way to go. Its a Deep cycle battery + cap. I will be getting one for my car when its done.


02-15-2012, 11:50 AM
has anyone converted the plug on an outback alternator to use on a bd legacy? i hear they've got a little more juice...

02-15-2012, 01:12 PM
Interested in something too that isn't $300+ since I have the older 2 wire/square plug alternator.

02-15-2012, 01:24 PM
Matty you can run a 3 wire alternator without issues. Just leave the blue wire disconnected.

"04 sti alternator:
1.Blue goes to ECU
2.Blue/red goes to main fuses
3.Black/white goes to cluster

2-wire alternator:
1.Black/red goes to cluster
2.White goes to main fuse box

Sti 3-wire is 1 2 3 with tab at top, 2-wire is 1 2 with tab on top" - NASIOC

02-15-2012, 02:08 PM
nice! i am so doing that. don't outback alts have another 15 amps or so?

02-15-2012, 02:38 PM
Forester alts have 90 amps... I beleive the 04 sti is 110 amps... your standard alt has I believe 75 or 80 amps.

02-15-2012, 03:15 PM
I believe Grafton is getting an upgraded alternator...

02-15-2012, 07:31 PM
Now where to find a 3 wire pigtail plug to wire in lol

02-18-2012, 08:29 PM
So I just picked up an alt from an '04 wrx, and it's got the newer style plug, but there's only 2 wires coming from it. How would I wire it into a '97 legacy gt?

edit: wrx, not sti

02-18-2012, 08:34 PM
post pictures please

02-18-2012, 11:14 PM
ill put some up in the am. i tried to install with a pigtail from an '00 outback, but i couldn't figure out the wiring, and im gonna need to get different terminal lugs for the power wires. the stud on the wrx alt is bigger, and although they can be removed on both alts, they dont match up, so i cant put the smaller stud onto the wrx alt.

the outback pigtail i pulled has three slots on the connector, but only two are used. i can't remeber the colors off hand, but ill post up pics and more info tomorrow.

02-18-2012, 11:18 PM
and yes im posting in a five year old thread.

deal with it. *puts on shades*

03-27-2012, 10:05 PM
I'll GLADLY deal with it as my alternator finally crapped out again and I have to replace it again and now have lights and goodies (no stereo though).

03-28-2012, 09:20 AM
you should upgrade the alt wiring. i pulled apart a harness at a junkyard to follow exactly where the wires from the alternator went. one of the power wires on the stud goes to the main fuse box power, and the other powers the a/c system relays (pretty sure), which are also on the main fuse box under the hood. one of the wires from the connector ties right into those power wires off the stud, and the last one is for the cluster signal when the alt isn't working.

i wired in an '04 wrx alt w/ no probs. the next step is to upgrade the wiring, now that i know where all of it goes, and what crimp on pins i need to get.

i have pics, i'll post 'em up soon. gotta put them on the comp first...

03-28-2012, 08:24 PM
I recently upgraded my alternator in my 96 Legacy L with a 190 amp unit from DC Power Engineering. PS. How come I've never been able to upload/attach a simple picture from my files? I have several photos of the alt installed. Puts out 14.7 VDC no matter how loud I run the system. The stock 85 amp alt would dip down to mid 11s

03-28-2012, 09:04 PM
SLi currently can not support photo uploads.

Please use this tutorial to upload any photo you wish --> viewtopic.php?f=41&t=23411 (https://sl-i.net/FORUM/viewtopic.php?f=41&t=23411)

03-28-2012, 09:24 PM
nice! i made a post on nasioc about those, they look like they're really well built. does it have that denso "hairpin" design? or the custom pulley on it? uploading pics now... i use imageshack to upload them. flikr is another image host.

after you upload it'll give you a link. copy and paste it here and add these around it [*img][/img*]
...but take these * things out. i had to add those so i could show you them.

03-28-2012, 09:32 PM

03-28-2012, 09:39 PM
does it have that denso "hairpin" design? or the custom pulley on it?
Both. https://www.dcpowerinc.com/11024-270-xp.html

03-28-2012, 09:41 PM
u only need 1 set of [img] tags.. i fixed ur last post.

03-28-2012, 09:45 PM
u only need 1 set of [img] tags.. i fixed ur last post.

03-29-2012, 12:21 AM

here's a pic of the alternator wiring pulled out of the harness and where it ultimately goes. i'll post up more pics and details tomorrow..

03-29-2012, 12:28 AM
btw, how do you like that alt? did you notice a big difference? did you get it for audio stuff or something else?

03-29-2012, 04:19 AM
Alt is great. No Remorse. Do not add a capacitor. Some people seem to think that somehow they are free energy?!? Well, now the already suffering alternator has yet another demand put onto it, charging the cap.

03-29-2012, 05:00 AM
Forester alts have 90 amps... I beleive the 04 sti is 110 amps... your standard alt has I believe 75 or 80 amps.

Would there be any harm done by putting in a larger alternator for a 96 Lego Wagon (running a system)?

03-29-2012, 05:06 AM
No harm. A high amp alternator simply means it is capable of supplying the higher load when required. It is not as if it is an un-controlled fire hose of current.

03-29-2012, 12:13 PM
Also upgrading your ground cables from the battery to the car and battery to the engine helped me the most. Go to a welding supply store and buy 1 or 0 AWG wire and make your own. The amount for current draw that the sub(s)/amp(s) ask for needs better grounds. upgrading the power wire to the sub(s)/amp(s) will help quite A lot too.

03-29-2012, 01:44 PM
I removed my 4 gauge big three upgrade and went with welders cable. I will be using welders cable from now on. Its cheaper and better with more, finer strands of copper. It's much easier to work with.http://i472.photobucket.com/albums/rr85/smstavros/P1000836.jpg

03-29-2012, 05:05 PM
Add an extra ground from the battery to chassis and engine to chassis, then run an extra positive from the alternator positive stud to your battery (with fuse, of course). This alone increases how much power you get from any alternator by giving the electricity an easier path to follow. I'm running about 1300 watts RMS and YES A CAP HELPS! It isn't free energy, but it softens the load you place on the alternator. Rather than a ton of big surges (can't be good for the regulator) you get a more consistent draw. A capacitor's best improvement is in sound quality, I noticed more punch and overall cleaner bass when I put mine on. The problem with caps is that people think it's a replacement for a good battery and high output alternator. It is not, it just levels out the load and gives the amp that extra bit of power when it needs it.

My system on the stock alternator with all the extra ground wire will still draw more power than my alternator can provide, at night the lights dim significantly at higher volumes, but there is no high/low flicker thanks to the cap. A WRX alternator is a good upgrade that can be easily found, and any parts store should be able to go into their book and tell you the amperage if you are going the parts store route. Otherwise you're looking at having someone build one for you.

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03-29-2012, 05:10 PM
another good ground upgrade is from the back of the right side alt bracket bolt straight to the battery. ill post pics of my 4awg setup, but welders cable sounds like a good idea, too. still more pics and descriptions coming....

01-14-2014, 09:18 AM
Bumping this thread, I picked up an alternator from a 2008 Legacy in my local wrecking yard (110 amp unit) and I'm trying to figure out how to retrofit the plug harness from a two prong square box to the three prong connector. Should I use the wires from a third gen legacy?