Jump to content
SAU Community

Recommended Posts

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.

post-17518-0-23166600-1422347358_thumb.jpg

Link to comment
https://www.sau.com.au/forums/topic/453163-alternator-upgrade/
Share on other sites

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

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.

  • Like 1

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.

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 .

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?

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?

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?

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Yes to both! Yes to standard ECU and tune, but exhaust is aftermarket. Unsure on brand. Actually have it sitting in at my desk haha! I have to set it up on my laptop but this is a great next step, will do. So I generally try to shift before 4.5K RPM most times. I largely don't do a lot of high-rev driving, but I will take it up to red 1-2x a week max, as I know the occasional "Italian tune-up" is good for these cars.  Oh wow, is this way better than what I'm getting. Does this mean there's a good chance I have an issue?   Thanks for all the info so far guys.
    • Old Son, did you re-use the Holden ABS in the new shell or try a different module?
    • Yeah, nah. I had the actuator rod off it today. The arm will not move at all. Neither out, nor in. Yeah, you'd think so, but I've been thinking about that. Even when the actuator rod fell all the way off at the beginning of this saga, it would build more boost and faster in lower gears than it would in higher gears, and you'd think that that was the opposite of what should happen. But I strongly suspect that there is a thing with the gearing getting the revs to rise faster, that there must be some transient effect with the gas flow rate rising quickly, that you don't get with the more steady state case of the higher gears. Keep in mind - the gate is not shut in either of my weirdnesses. So things are not "normal". We normally think about a turbo spooling up (below the wastegate target) with the gate shut. I have all sorts of mental models running now where the gate is a little bit open, and having it stuck open allowing gas out while it should be going through the turbine has all sorts of weird effects (in these mental models). I'm thinking in the higher gears, the ex mani pressure builds to the point where enough gases spill out the wastegate to just prevent the pressure rising much more at all, or just creeping up, all the whole the revs are increasing and getting closer to the point where a gear shift becomes necessary.
    • Is it possibly wastegate actuator itself is sticking, or even the rod to flapper? Otherwise I reckon things are getting a bit rusty/worn   Also odd it won't boost in 3rd to 5th, but will in 1st, I'd expect the other way around with it slightly open as there's more time on your way to redline for it to spin up
    • Does anyone know ow what these two plugs are for and if they should be unplugged? Just put the dash back together and can't remember if these were plugged in before or unplugged! (Blue and white plugs) 🤦🏽‍♂️
×
×
  • Create New...