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Discussion Starter · #1 ·
Going to be putting a sub and amp in my car in a few weeks time. Its proper kit, the amp is rated at 1200W RMS and I get the feeling the alt on my 99 211 won't really be able to provide the power needed when I up the volume. Going to get a better battery and sort TB3 but to make sure the battery actually gets charged I'm going to need a bigger alt. Are there any high output alternators off the bigger models that are a straight swap? I'm guessing the 220D alt would be an upgrade but I'm not sure how much power they put out.

Thanks
 

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I dont think the diesal alternator would fit but most k series alternators will.
The 1.1l to the 1.6l seam to be the same the 1.8 is a more powerfull version. You should be able to fit a 1.8 version to your engine if you really need power that much. The running should be the same because the MAP sensor should detect the load.

IMO you should try your system with your original alternator to see how things go. The ECU will detect if the battery gets low and raise the revs to about 1100rpm to produce more power

thanks
 

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The chances of you using 1200 watts is slim I wouldn't reckon that you will need to change the alternator.

What is the rating of the fuse(s) on the amp itself??

If you do change the MGF uses an 85 amp alternator which will give you 20 amps more than the standard unit and it is a direct replacement.
 

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audio

Going to be putting a sub and amp in my car in a few weeks time. Its proper kit, the amp is rated at 1200W RMS and I get the feeling the alt on my 99 211 won't really be able to provide the power needed when I up the volume. Going to get a better battery and sort TB3 but to make sure the battery actually gets charged I'm going to need a bigger alt. Are there any high output alternators off the bigger models that are a straight swap? I'm guessing the 220D alt would be an upgrade but I'm not sure how much power they put out.

Thanks
if you are going to be installing a large audio system i would definately buy one of these

http://cgi.ebay.co.uk/VIBE-POWER-CA...7QQihZ009QQcategoryZ14932QQrdZ1QQcmdZViewItem

these caps will reduce any interference and also supply your amp with the power it needs ,when it needs it to hit those low bass notes

therefore it will put a lower demand on your battery.
 

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if you are going to be installing a large audio system i would definately buy one of these

http://cgi.ebay.co.uk/VIBE-POWER-CA...7QQihZ009QQcategoryZ14932QQrdZ1QQcmdZViewItem

these caps will reduce any interference and also supply your amp with the power it needs ,when it needs it to hit those low bass notes

therefore it will put a lower demand on your battery.
Uh-oh! :rolleyes:

I'd say stick with the same alternator unless you are going to be constantly driving the new kit hard. New battery and TB3 are the best to start with.

Rich.
 

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i to think your alternator will cope fine.

i have a JBL setup in mine with a 1000 watt amp and a 1000 watt sub and 330 watt 6x9's i have no problems atall, sometimes you can SLIGHTLY see a dimmer of the headlights if u wack it right up but only on a realy dark road i notice it, and its not anoth to do anything about
 

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Discussion Starter · #9 ·
Thanks for the comments.

Going to be installing a voltmeter anyway to keep an eye out for any voltage drops. I know the amp (SPL Dynamics S-1200D) won't be giving out a constant 1200 W and will only do that if I played a sine wive, it's a good brand so it will probably be under-rated as well.

A bit off topic but on the note about the ECU raising the rpm, when I first start my car it has quite a high idle (~1200rpm) but usually once I've reached my destination it drops nearer to what it should be (~800). Is this to charge the battery or just because it's warming up?
 

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A bit off topic but on the note about the ECU raising the rpm, when I first start my car it has quite a high idle (~1200rpm) but usually once I've reached my destination it drops nearer to what it should be (~800). Is this to charge the battery or just because it's warming up?
Auto Choke.
 

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It's not auto choke as such as it doesn't enrich the fuel mixture.
The ECU raises the revs on a cold engine to bring more air/fuel in until up to operating temperature. This acheives several things, gets the Cat up to operating temp quickly, gets the the lambda up to temp, gets the engine up to temp quickly and reduces emmisons.
There other reasons too, but those are the main ones.
It's normal for cold idle to be around 1250 rpm and normal idle at 875 rpm.
 
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