<VV> High Capacity Alternators

[Jim Davis]

Remember alternators are rated at 70 degrees core temp and 8,000 rpm.  
On a Corvair the core temps reach about 110 when supplying 10 amps on a 
90 degree day.  The output potential drops about 1% per degree for the 
core temp.  The UltraVan engine compartments runs about 110 on a 90 
degree day. Pulling 60 amps from the alternator raises the core temp to 
about 130 F; thus a 140 amp alternator is capable of producing only 75 
amps and at 8,000 rpm.  Based on my traveling for 16 years in an 
UltraVan.  I would say you are lucky to get 60 amps out of a 140 amp 
12SI alternator at 3,000 engine rpm (4,500 alternator rpm).
Jim Davis


On 11/4/2015 7:47 PM, Daniel Monasterio González via VirtualVairs wrote:
> Jim,
>
> If it were my UltravanŠI'd use the 74 Amp. Alternator and triple battery
> capacity.
>
> Just my opinion.
>
> Daniel Monasterio
>
> On 04/11/15 19:16, "Jim Davis via VirtualVairs" <virtualvairs at corvair.org>
> wrote:
>
>> If you had a Corvair powered UltraVan, you would understand the need for
>> a 140 amp alternator.  The frig and ice maker alone draw 60 amps.
>> Jim Davis
>>
>>
>>   On 11/4/2015 7:04 PM, hallgrenn via VirtualVairs wrote:
>>>       
>>> ,,,,,Unless you've got a car amp/speaker setup designed to rock the
>>> world why would you need an alternator with more than 70 to 80 amps
>>> common to GM cars of the 70s.  Larger capacity also means more load on
>>> the engine when charging.
>>> Bob Hall
>>>
>>>
>>> Sent on the new Sprint Network from my Samsung Galaxy S®4
>>>
>>> -------- Original message --------
>>> From: Frank DuVal via VirtualVairs <virtualvairs at corvair.org>
>>> Date: 11/04/2015  7:22 PM  (GMT-05:00)
>>> To: virtualvairs at corvair.org
>>> Subject: Re:  Autozone alternators
>>>
>>> Quadruple? You might be overstating your case. Double I would believe.
>>> Stock: 37 amp
>>> Double: 74 amp
>>> Quadruple: 148 amp
>>>
>>> Not many 70s/80s Chevys had 150 amp alternators.
>>>
>>> Frank Duvall
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