Voltage car running?

[240slidekat]

hey guys what are you seeing on your voltage meter when the car is on and running on a rb25 stock alternator? Reason i asked is when i turn on the car the first 5 minutes or so, the voltage reads around 13.4-13.7 then itll gradually go down to 13.0-13.1 and holds steady. That just seems low to me. That sound like an alternator going bad? or a battery?

[USMCgetsome]

should be 14 or damn near

[eh?]

Are you checking with a good meter right off the alternator?

[240slidekat]

right now im just going of what my apexi gauge is saying. i am going to check with a multi meter tomorrow when i get a chance.

[eh?]

I wouldn't put much trust in a gauge. Check it right off the alternator and make sure you put the ( - ) probe on a good cleaned ground.

[240slidekat]

ok this is what i got...

car on: 13.3 at the battery13.7 at the alternator

car off ignition on:11.96 battery

[eh?]

Is this with electric fans running? It doesn't seem that bad at all to me, maybe just clean up the grounds.

[240slidekat]

yea this is with the electric fans on. with the lights on its another .2-.3 less.

[eh?]

I wouldn't worry at all.

[240slidekat]

it should be ok during high boost applications right?

[eh?]

Don't see why not, If anything I would be worried about the coils.

[RustspecS13]

That's normal for a stock RB/KA/VG30E alternator. I swapped to a VG33E aka quest alternator and now I run 14V solid.

Even with everything on, 2 ele fans, heater, radio, headlights it doesn't get below 14v. Its also a 125a, vs the stock 70-80. I don't think its the amperage difference its the regulator is much better on the quest. But its about $120 I think and it makes a huge difference.

Ive heard of people needing a retune after swapping alts so I'd do it before you do some serious work. That extra volt will help out with spark and fuel pressure under high load and that's always good.

~Alex