Alternator Upgrade

[PSI086]

Having voltage issues with my alternator and was looking at maybe doing an upgrade if it was necessary. What sort of amps would be sufficient for my set up. Car is a VL turbo running 2 x 044 pumps (1 is staged to come on at 10psi) , 6 x LS2 coils, 750cc low impedence injectors, Haltech ps2000, no thermo fans, basic stereo with no amps and battery in the boot. Currently have a RB25 alternator in the car which is 80 amps but my be failing higher up in the rpm as you can see in the data log below. Ramped up fine on 17psi but had a smaller drop in voltage, 22psi it broke down under boost.

[Dose Pipe Sutututu]

you're having the same issue as I am

I'm currently running a 85AMP VL Commodore alternator (Bosch replacement) after replacing my 80AMP R33 alternator.. has gotten a touch better, but I'm getting around 12.8volts up top.. and the idle voltage is horrible.

I'm contemplating in getting this one:

http://www.ebay.com.au/itm/Nissan-Skyline-HR33-GTS-RB25DE-120-Amp-3-0L-6-Cyl-Turbo-Non-Turbo-Alternator-/131390382961?pt=AU_Car_Parts_Accessories&hash=item1e977a2371

[R_34]

I would look at upgrading the wire going from the alternator to the battery.

I checked on my RB20, I have 14.1V at idle on the battery but got 15.3V on the alternator.

I investigated a little more and I found that the wire coming from the alternator going to the power connector next to the battry to power all the car is responsible for the total loss in voltage.

So try to check it on your car and upgrade it if you find that is voltage is much higher than the one you see on your battery. Much cheaper and more efficient than getting a more powerful alternator.

[Dose Pipe Sutututu]

I've added a second 4ga feed and still have issues.

It's because the alterntor itself cannot produce the voltage to suit the car's demand.

I tested the voltage on the alterntor and it's only like 0.2 volts higher than what's being logged on the ECU.

I'm assuming that the Bosch alternator has issues working at high RPM And the factory unit well is just old.

[discopotato03]

I found cleaning all the earth points in the engine bay made a difference to my S2 33 . Also the voltage regs don't last forever . I got caught out a while back and had to have my OE alternator rebuilt . The reg is the same as those on early Falcon Mitsi alternators - EA EB from memory . I don't think the OE R33 alt is listed in Australian parts catalogs but long time auto sparkys can usually work it out .

My car shows around 14V at the battery and a little higher at the alternator so good enough for me ATM .

[Dose Pipe Sutututu]

I found cleaning all the earth points in the engine bay made a difference to my S2 33 . Also the voltage regs don't last forever . I got caught out a while back and had to have my OE alternator rebuilt . The reg is the same as those on early Falcon Mitsi alternators - EA EB from memory . I don't think the OE R33 alt is listed in Australian parts catalogs but long time auto sparkys can usually work it out .

My car shows around 14V at the battery and a little higher at the alternator so good enough for me ATM .

Adrian, what voltages are you getting with your headlights on & the rear demister?

[Missileman]

I tooks some reading a while ago.... http://www.sau.com.au/forums/topic/386795-battery-alternator-issue/#entry6170028

[PSI086]

My alt to battery wiring is brand new as I've just put a new engine harness in the car. Used 16mm welding cable which should be heaps I'd imagine. Is the size of the sense wire critical? I might pull the engine to chassis earth strap off and clean the connections again just to eliminate that.

Also what sort of amps would be sufficient for my set up? Something around the 90 mark would be heaps I'd imagine or am I bettter off upgrading to a 105-110amp unit?

[t_revz]

you dont need to upgrade amperage for your requirements. 80 amps is easily sufficient unless the stereo was a killer. it held 14v flat up till about 5k then something happened. looks like either something turned on that pulled excessive power or had a short. the vibration at that rpm is causing something to move(loose connection). the ignition supply to the alternator plug is failing.

does it dip revving up quickly? accelerating quickly or only when speeding up slowly?