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Old 04-27-2010, 06:42 PM   #1
MGargano
 
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Exclamation Alternator Pulley Question

Can anyone tell me if the alternator pulley from a Scion xA/xB will fit on the Yaris alternator? It seems they take different alts, but I'm wondering if the pulleys are the same.

NST sells an overdrive pulley for the xA/xB, which has the same belt size and offset as the Yaris, so I'm wondering if it would work on the Yaris alternator?
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Old 04-27-2010, 06:45 PM   #2
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Nevermind...just got word back from NST that the center bore size is different between the xA/xB and the Yaris. At least now I have a definite answer.

Has anyone had luck finding an overdrive alternator pulley for the OEM Yaris alt?
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Old 04-27-2010, 06:47 PM   #3
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Out of curiosity...what exactly will that accomplish? More power output from the alt?
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Old 04-27-2010, 06:48 PM   #4
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Supposedly, higher/more consistent output when the engine is idle/at low RPM
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Old 04-27-2010, 07:11 PM   #5
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If anyone's interested, I was able to custom order a 20% overdrive alternator pulley from Mike at NST.

Combined with a 10% underdrive crank pulley, the 20% overdrive alt pulley should get me a 10% gain on the alt.

The way he and I figured it, using a 10% overdrive alt pulley & 10% underdrive crank pulley would've been pointless, as the two would cancel each other out and I'd end up in the same place I'm at now.

I'll have a definite answer in 5-6 weeks.
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Old 04-27-2010, 07:15 PM   #6
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Quote:
Originally Posted by MGargano View Post
Supposedly, higher/more consistent output when the engine is idle/at low RPM
I should have prefaced that I'm just learning about cars. So with that being said, higher/more consistent output will get us....better battery life? better performance on after market electronics (amps and such)?

Sounds like a simple and cost effective mod, as long as the results are effective anyways.
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Old 04-27-2010, 08:14 PM   #7
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Originally Posted by suckerface View Post
I should have prefaced that I'm just learning about cars. So with that being said, higher/more consistent output will get us....better battery life? better performance on after market electronics (amps and such)?

Sounds like a simple and cost effective mod, as long as the results are effective anyways.
On my car, for some reason, the voltage runs ~14.1 while I'm moving at a decent speed. At idle/lower RPMs, the voltage drops to ~13.5, with or without the amplifiers, etc on.

I'm hoping this overdrive pulley will allow for a higher/more consistent voltage output at idle/lower RPM.
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Old 04-28-2010, 12:59 AM   #8
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You have a lot to learn.
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Old 04-28-2010, 06:54 AM   #9
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You have a lot to learn.
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Old 04-29-2010, 03:43 AM   #10
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Quote:
Originally Posted by MGargano View Post
On my car, for some reason, the voltage runs ~14.1 while I'm moving at a decent speed. At idle/lower RPMs, the voltage drops to ~13.5, with or without the amplifiers, etc on.

I'm hoping this overdrive pulley will allow for a higher/more consistent voltage output at idle/lower RPM.
You don't need to change anything, unless you're increasing the electrical load at idle, in which case it would be better to put a higher output or larger alternator. Basically, the alternator will increase output with increase in demand. In other words it is load sensitive.

That being said, the xB has a larger alternator for increased output for audio upgrades. That was anticipated because it is geared for the youth market.
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Old 04-29-2010, 07:21 AM   #11
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You don't need to change anything, unless you're increasing the electrical load at idle
The problem I'm having is that the dip in voltage occurs with or without the presence of a load. Mine seems to fluctuate based on the car's speed/RPM, rather than what I'm drawing.

Quote:
Originally Posted by yaris-me View Post
Basically, the alternator will increase output with increase in demand. In other words it is load sensitive. :smile
I really appreciate your input, especially since I'm just learning about this myself, but I haven't not found this to be the case. Even when I turn everything off (HIDs, amplifiers, etc), the voltage drops (sometimes as low as 13.2v) when at idle.

If I turn everything back on, the voltage dips even lower for a second, then stabilizes back around 13.4 - it never increases anywhere near 14.1 at idle, regardless of load.
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Old 04-29-2010, 11:50 PM   #12
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Quote:
Originally Posted by MGargano View Post
The problem I'm having is that the dip in voltage occurs with or without the presence of a load. Mine seems to fluctuate based on the car's speed/RPM, rather than what I'm drawing.



I really appreciate your input, especially since I'm just learning about this myself, but I haven't not found this to be the case. Even when I turn everything off (HIDs, amplifiers, etc), the voltage drops (sometimes as low as 13.2v) when at idle.

If I turn everything back on, the voltage dips even lower for a second, then stabilizes back around 13.4 - it never increases anywhere near 14.1 at idle, regardless of load.
That is why there's a battery. The alternator will adjust and cover the demand, if it's not too great. If you're often faced with a drained battery, then you need to do something.
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