Which Alternator

Update: I got the 200 amp from KMJ


I've read many threads, I've talked to KMJ on Facebook. I just went to my local alternator shop and the guy told me he could build one for me tomorrow for $250 with a 1-year warranty. He said $140 to install any alternator (if I bring my own or buy from him). What do you think, I just want to get the best for my car. Btw the alt shop is less than a mile from me. Also, he sadly says he doesn't carry big 3 kits so I will have to order one anyways.

The first thing I'd want are some references. How many alternators has he re-built? Any for '03-'04 Cobras? Any HD alternators?

1-year is not a good warranty! Some have a life-time warranty.

I was going through options the other year when replacing mine - I ultimately ended up going with a KMJ 200 amp. Better warranty and a similar price to local builds, but he has more options and it's less hassle.

brigs said:

I was going through options the other year when replacing mine - I ultimately ended up going with a KMJ 200 amp. Better warranty and a similar price to local builds, but he has more options and it's less hassle.

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thats what I was thinking, what is his website? and is he on this forum?

Website: KMJ Alternators

SVT_Nthn said:

I've read many threads, I've talked to KMJ on Facebook. I just went to my local alternator shop and the guy told me he could build one for me tomorrow for $250 with a 1-year warranty. He said $140 to install any alternator (if I bring my own or buy from him). What do you think, I just want to get the best for my car. Btw the alt shop is less than a mile from me. Also, he sadly says he doesn't carry big 3 kits so I will have to order one anyways.

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So basically the price of the KMJ with a coupon.

I went the kmj route with a pieced together big 3 kit. Total was $350. May want to go that route. 1 year warranty is sh*t.


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KMJ here as well. No issues, minor modification.

I had my alt bracket powder coated after I clearanced it and you cant even tell that its been modified.

I imagine my opinion won't be very popular given how everybody gets testy about alternators here and wants some super custom built one, but when my OEM gave out (~200k) I just went to autozone and bought a generic reman'd one. And it's been working fine for like 50k+. And it fit perfectly fine and charges perfectly fine.

efnfast said:

I imagine my opinion won't be very popular given how everybody gets testy about alternators here and wants some super custom built one, but when my OEM gave out (~200k) I just went to autozone and bought a generic reman'd one. And it's been working fine for like 50k+. And it fit perfectly fine and charges perfectly fine.

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same here, when i read these alternator threads and how folks say that "terminators eat alternators", i always wonder if i'm just lucky. because i've only ever changed one alternator in over 205k miles of driving.

and i think i only had to change that one because i put on the wrong size belt that was too tight.

03yllwguy said:

So basically the price of the KMJ with a coupon.

I went the kmj route with a pieced together big 3 kit. Total was $350. May want to go that route. 1 year warranty is sh*t.


Sent from my iPhone using the svtperformance.com mobile app

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already bought my KMJ alt eearlier

P49Y-CY said:

same here, when i read these alternator threads and how folks say that "terminators eat alternators", i always wonder if i'm just lucky. because i've only ever changed one alternator in over 205k miles of driving.

and i think i only had to change that one because i put on the wrong size belt that was too tight.

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mine looks like its the factory one, ill see when i pull it out

Just ordered my KMJ, I am on my 3rd failure with factory then reman, might as well try KMJ. The reman that just failed is less than 8 months old, one previous track event and a few street miles and just failed session 4 out of 4 at a track event this weekend - I'm sick of it. What pully sizes are you putting on your KMJ?

NGO said:

Just ordered my KMJ, I am on my 3rd failure with factory then reman, might as well try KMJ. The reman that just failed is less than 8 months old, one previous track event and a few street miles and just failed session 4 out of 4 at a track event this weekend - I'm sick of it. What pully sizes are you putting on your KMJ?

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I got the KMJ, tbh im not sure what pulley, I was gonna ask my mechanic since I am unsure. I was under the impression that you just use the one on the prev alternatorr

My local guy upgraded my alternator as well. After the 3rd rebuild i shelved it and bought one from j2fab. Its been great in the 2yrs ive had it.

brownsvo said:

My local guy upgraded my alternator as well. After the 3rd rebuild i shelved it and bought one from j2fab. Its been great in the 2yrs ive had it.

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i ended up buying a kmj, just waiting on it now

I bought a KMJ 200 Amp as well with the big 3 kit. Will be arriving next week.

The great thing about KMJ is he offers a lifetime warranty to the original purchaser no questions asked. He's good ppl....you have a problem 5yrs down the road you send it to him and he'll sort you out. And he goes out of his way to help and respond......I don't think i've ever messaged him and waited more than 20-30min for a response....you just can't put a price tag on that.

You do have to clearance the alternator bracket just a bit for the KMJ200 as its a bit larger than the factory unit, but its a quick job with an angle grinder. Good time to do a BIG3 kit while you're in there. He offers those too. You can get the whole kit for like $299 which I personally think he undercharges for.

Alternator pulley size should be based on what size your lower crank pulley is....Metco has a chart for this. If you're running a stock/caged lower you don't need to go up in size on the alt pulley although some people do anyway just to keep from overspinning it. The popular 4lb lowers require a 3.2in alt pulley......Metco and LFP sell them.

I bought a 200amp eBay special and the big 3 wiring upgrade and did the whole thing myself. It was really easy just a little time consuming.