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 Post Posted: Fri Feb 06, 2009 7:33 am 
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a friend of mine whose an electircal engineer for Ford in the UK was telling me the other day that most alternators are good for 18000 RPM. Max ratio in a road car is 3-1 but for a race car reving past 7K 2.5-1 is a good guide for longevity of the brushes and bearings etc.

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 Post Posted: Fri Feb 06, 2009 7:53 am 
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PSweeney wrote:
a friend of mine whose an electircal engineer for Ford in the UK was telling me the other day that most alternators are good for 18000 RPM. Max ratio in a road car is 3-1 but for a race car reving past 7K 2.5-1 is a good guide for longevity of the brushes and bearings etc.


I appreciate that info.  I can't use the 4" pulley because it's a single center bolt so I have to go with the 5.25".  With the 2 1/2" pulley that's on the alternator that gives me a 2.1:1 ratio. The way I had it figured that would spin the alternator to 16,800 with the engine at 8k.  I was thinking of using a bigger alternator pulley but it looks like I'm good with what I have.  :-$

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 Post Posted: Fri Feb 06, 2009 8:06 am 
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I put a deeper larger one on ours. The bad part is you have to pick up the RPM before it kicks in. So sometimes it won't charge until you get it above 1200 after you start it.

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 Post Posted: Fri Feb 06, 2009 10:16 am 
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WR169 wrote:
I put a deeper larger one on ours. The bad part is you have to pick up the RPM before it kicks in. So sometimes it won't charge until you get it above 1200 after you start it.





That's how most of them work and mine does that also...After I start it you just need to give a little throttle and then it's good and charging =;  =;

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 Post Posted: Sat Feb 07, 2009 6:56 pm 
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I got the alternator mounted and the belt & pulley worked out. Now I'm trying to decide what gauge wire to run. I know what I would use for a short run but I'm not sure about a 12' or so run. I'm thinking around 10 maybe 8?

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 Post Posted: Sat Feb 07, 2009 7:49 pm 
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I have 10 from the starter to the alt. You don't have to run it back to the battery.

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 Post Posted: Sat Feb 07, 2009 9:05 pm 
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Chuck,

I think you're better off with two large, dedicated wires, all the way back to the battery.  

I have a 2-0 from the positive terminal of the altenator back to the positive terminal of the battery, and a 2-0 from the altenator case back to the negative terminal of the battery.

This solved some issues I had with my data logger.

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 Post Posted: Sat Feb 07, 2009 9:30 pm 
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WR169 wrote:
I have 10 from the starter to the alt. You don't have to run it back to the battery.




How does the safety switch work wired like that???? It will back feed the system and keek running even if you turn the switch off O:)  O:) ...

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 Post Posted: Sat Feb 07, 2009 9:33 pm 
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gearhead1011 wrote:
I got the alternator mounted and the belt & pulley worked out. Now I'm trying to decide what gauge wire to run. I know what I would use for a short run but I'm not sure about a 12' or so run. I'm thinking around 10 maybe 8?




Chuck a #10 won't cut it...I was going to use a #8 but found a #6 in Tractor supply that is welding wire..It has a very thick tough casing and very thin stranded wire the bends very easy....You know that you need a decent wire to run that distance to carry that amperage...  =;

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 Post Posted: Sun Feb 08, 2009 6:28 am 
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I also run #6...from the alt. to the battery side of the switch


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 Post Posted: Fri Feb 13, 2009 3:32 pm 
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interesting facts.....

http://www.cvrproducts.com/alternator_tech.html

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 Post Posted: Fri Feb 13, 2009 5:10 pm 
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Hey I picked the right wire. =;  Barry the field wire is on the small post on the starter side of the shut off switch. so when the switch is off the field is off.

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