HO Alternator Question

[Jonnyswboy]

I just got a quote from BrandX for a 2010 Mazda 6 2.5L 4-Cyl:

Most vehicles with 4 cylinders or less it is generally not recommended to go over 270 amps maximum.

250 amp large case is 445$,
270 amps is 465$,
370a is 535$,
390 amps is 565$.

The 250 amp can use the stock pulley diameter and is recommended over most units for maximum durability. The 270 and 390 idle around 200 amps and have close to Small case and custom large case

I have a few questions.

1. I really would like to use a 390A for my Salt-8 and was wondering what risks or downsides it would pose using a 4-cyl motor?
2. How will BrandX perform vs Singer?
3. If I get one that is incompatible with the stock pulley diameter, will I just need a different size belt and otherwise it will be bolt-in replacement?

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[Popwarhomie 5,000+ posts]

If it's a daily driver I would stick with 270 and under. If not send it.

 

[Jonnyswboy]

It is my daily. But I have 170HP, and apparently 1.5kW is equal to 2hp loss. So I think I'm gonna send it with the 390.

 

[Firewalker]

Brand X is known to reuse old stuff vs Singer which doesn't. I would go with Singer all day long vs Brand X

 

[Buck 5,000+ posts]

I know people who run Brand X and swear by them. I have a very long time customer of mine with two brand x 270's on a Suburban on a Salt 8k and they put in work. Brand X seems to be as good as some of the better, brands, from everything that I've seen from them, so far.

Sometimes big alts have crappy idle output, on high revving motors, sometimes they have no output until 1000-1200 rpm. I would personally go with the biggest one.

The alt pulley will only be so small if your engine revs up to 6k rpm or more. The alt can only spin so fast, so it has to be geared not to over-spin on the top engine RPM, by the size of the alt pulley vs the crank pulley.

I'd get the 390a, and run a decent bank of lithium or something that's lighter with that small car. While idling, you need something with decent reserve power to make up potentially for low alt output, but I would personally get the biggest alt you can fit, see if you can fit more than one alt even, if at all possible.

 

[Firewalker]

Was just going off of what I have been told by a couple people is all. I know a couple others have either here or at DIYMA have had similar issues with them. So who knows. Tbh I am too drugged up at this point from the surgery to really care,lol.

 

[Sman83]

With alts I would think the quality and weight of copper would be the most important factors to consider. Do these two companies include that info?

 

[metalheadjoe 10+ year member]

There's not enough copper in an alternator for any manufacturer to increase their cost, though they might quote the price increase to justify their price increase..