FI SP4 stock 170 amp alt. battery and amp help.

[Rick Griffin]

I got a good deal on a FI sp4 15 and have a 170 amp stock alt in my 06 bmw. Would like to start with stock alt for a while, just need suggestions on what amp I can use to push it. Bear in mind, 170 amp stock alt, I was thinking a good 2500 watt rms amp would push it ok with a battery upgrade. Opinions and options would be helpful.

[Mr DeeBeez]

Sq 2200. I have mine on a sq3500, but the 2200 would push it pretty nicely.

Shouldn't need a ho alt, but make sure you do big 3

[Rick Griffin]

Sq 2200. I have mine on a sq3500, but the 2200 would push it pretty nicely.

Shouldn't need a ho alt, but make sure you do big 3

Thats what I was thinking, that or a dd m3c. What about a batt though, 1 extra batt in the back should be ok right? xs 3100?

[Mr DeeBeez]

I had my 3500 in my blazer with stock alt, d3100 up front and xp3000 and I was able to hold low 12's.

A 2200 should be ok with a d3100 in back.

Is your sp4 a d1 or d2?

[Rick Griffin]

D2

[Guest]

I have crescendo encore 4.5k with 2 extra batts in the back on D1 SP4 15", no light dimming no voltage struggling

factory alt, no big3, 3 runs of 1/0 going from my (-) rear batts to the metal ground

@2ohm it does 2,734 watts on the SMD amp dyno

If I ever wanted to go 1ohm or lower it would require alot more electrical

so I like 2ohm for now and 2.7k is good for the SP4

The only highoutput alternator for my SUV is $800 from DC power

I had a crescendo bc2000 @.5ohm in my mustang on this sub

with 2 extra batts in the back and 250amp mechman alt

never went below 12.8V

[Rick Griffin]

you have a D2 ohm sub wired at 2 ohms?

[Guest]

you have a D2 ohm sub wired at 2 ohms?

sorry I meant I have a D1 @2ohm

[SLYentist]

i imagine that the alternator is that large for a reason. it doesn't make sense for BMW to put in a higher output alt than what's required, from a economic and reliability standpoint. I wouldn't put an huge amp on it, just because it's a 170 amp. The stock electronics in 04+ BMWs is pretty substantial.

[Rick Griffin]

I agree, thats why I was asking about how much power, with big 3 and and extra battery, about how much power or size of an amp I might be able to run without significant drop? I was thinking an aq2200d or possibly a saz 3000d but I dont know if that will be too much.