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

    • I'm looking for some real world experiences/feed back from anyone who has personally ran a EFR7670 with a 1.05 exhaust housing or a .83 I'm leaning towards the .83 because its a street car used mostly for spirited driving in the canyons roads. I"m not looking for big numbers on paper. I want a responsive powerband that will be very linear to 8000 rpm. I dont mind if power remains somewhat flat but dont want power to drop off on top. The turbo I've purchased is a 1.05, although the mounting flange T3 vs T4 and internal vs external waste gates are different on both housings, I not concern about swapping parts or making fabrication mods to get what I want. Based on some of the research I've done with chat gpt, the 1.05 housing seems to be the way to go with slightly more lag and future proofing for more mods but recommends .83 for best response/street car setup. AI doesn't have the same emotions as real people driving a GTR so I think you guys will be able to give me better feed back 😀   
    • Surely somebody has one in VIC. Have you asked at any shops?  Is this the yearly inspection or did you get a canary?
    • This is where I share pain with you, @Duncan. The move to change so many cooling system pieces to plastic is a killer! Plastic end tanks and a few plastic hose flanges on my car's fail after so little time.  Curious about the need for a bigger rad, is that just for long sessions in the summer or because the car generally needs more cooling?
    • So, that is it! It is a pretty expensive process with the ATF costing 50-100 per 5 litres, and a mechanic will probably charge plenty because they don't want to do it. Still, considering how dirty my fluid was at 120,000klm I think it would be worth doing more like every 80,000 to keep the trans happy, they are very expensive to replace. The job is not that hard if you have the specialist tools so you can save a bit of money and do it yourself!
    • OK, onto filling. So I don't really have any pics, but will describe the process as best I can. The USDM workshop manual also covers it from TM-285 onwards. First, make sure the drain plug (17mm) is snug. Not too tight yet because it is coming off again. Note it does have a copper washer that you could replace or anneal (heat up with a blow torch) to seal nicely. Remove the fill plug, which has an inhex (I think it was 6mm but didn't check). Then, screw in the fill fitting, making sure it has a suitable o-ring (mine came without but I think it is meant to be supplied). It is important that you only screw it in hand tight. I didn't get a good pic of it, but the fill plug leads to a tube about 70mm long inside the transmission. This sets the factory level for fluid in the trans (above the join line for the pan!) and will take about 3l to fill. You then need to connect your fluid pump to the fitting via a hose, and pump in whatever amount of fluid you removed (maybe 3 litres, in my case 7 litres). If you put in more than 3l, it will spill out when you remove the fitting, so do quickly and with a drain pan underneath. Once you have pumped in the required amount of clean ATF, you start the engine and run it for 3 minutes to let the fluid circulate. Don't run it longer and if possible check the fluid temp is under 40oC (Ecutek shows Auto Trans Fluid temp now, or you could use an infrared temp gun on the bottom of the pan). The manual stresses the bit about fluid temperature because it expands when hot an might result in an underfil. So from here, the factory manual says to do the "spill and fill" again, and I did. That is, put an oil pan under the drain plug and undo it with a 17mm spanner, then watch your expensive fluid fall back out again, you should get about 3 litres.  Then, put the drain plug back in, pump 3 litres back in through the fill plug with the fitting and pump, disconnect the fill fitting and replace the fill plug, start the car and run for another 3 minutes (making sure the temp is still under 40oC). The manual then asks for a 3rd "spill and fill" just like above. I also did that and so had put 13l in by now.  This time they want you to keep the engine running and run the transmission through R and D (I hope the wheels are still off the ground!) for a while, and allow the trans temp to get to 40oC, then engine off. Finally, back under the car and undo the fill plug to let the overfill drain out; it will stop running when fluid is at the top of the levelling tube. According to the factory, that is job done! Post that, I reconnected the fill fitting and pumped in an extra 0.5l. AMS says 1.5l overfill is safe, but I started with less to see how it goes, I will add another 1.0 litres later if I'm still not happy with the hot shifts.
×
×
  • Create New...