Alternator Switch

[R32 TT]

i'm looking to run 2x 100w headlights, + 2x 55w lights (drifting in places with no lighting, or poor lighting), twin shrouded thermo's behind the radiator, 2x thermo fans in front of the radiator (1 in front of the oil cooler, 1 in front of p/s cooler), if you think that + all the ignition/fuel pump/accesories/ecu etc etc doesn't chew a bit, then you're kidding yourself. once you consider the inefficiencies of the alternator, it's probably not such a insignificant figure, but hey, that's just my opinion.

I could be wrong, but lets say the Alternator is 100A unit. That's 100A x 12v = 1200Watts (1.2 Kw) at full load. A bit of googling suggests alternators are about 50% efficient. So to provide a full blown 100A continous to drive all your accessories, lights, pumps, fans etc would be up to 2.5kw.

Does that sound right? (Auto Sparkies please correct me)

(by the way, I am not arguing with you, if you want to save anything you can, then go for it - but this might be the figure you're talking about saving if what I say above it correct?) Worth weighing up against the possibility of the extra hassle involved that's all.

[nisskid]

I could be wrong, but lets say the Alternator is 100A unit. That's 100A x 12v = 1200Watts (1.2 Kw) at full load. A bit of googling suggests alternators are about 50% efficient. So to provide a full blown 100A continous to drive all your accessories, lights, pumps, fans etc would be up to 2.5kw.

Does that sound right? (Auto Sparkies please correct me)

(by the way, I am not arguing with you, if you want to save anything you can, then go for it - but this might be the figure you're talking about saving if what I say above it correct?) Worth weighing up against the possibility of the extra hassle involved that's all.

if it was a figure like that with no additional free revving response, then i probably wouldn't bother, but it's worth remembering, it would literally be about a half hour job, if that, people spend a lot more time making amazing looking CAI's which would give you barely that.

[Duncan]

Well, I reckon do a dyno run with and without the alternator on the fan belt (remember to still run the water pump of course) and see what the maximum difference is. I'm all for improvements but I suspect this is too marginal to chase.

One other item worth mentioning - I run an underdriven fan and alternator pulley which is another way of reducing the drag. I did it for increased cooling but it should mean less drag from the alternator as it turns 30% less