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Re: Electric fans & amperage

To: triumphs@autox.team.net
Subject: Re: Electric fans & amperage
From: AMfoto1@aol.com
Date: Tue, 24 May 2005 15:19:49 EDT
Good point! And one many folks don't think about until they find their 
headlights look more like fireflies every time the fan kicks on at night!

The typical original 22 amp TR6 alternator would have been challenged. But, 
with a 55 amp unit you should be okay, unless you happen to be running the fan, 
a pair of 100W halogen driving lights, a stereo system and A/C all at the 
same time. You have to consider the total potential load on the electrical 
system.

It can also be a good idea to test the alternator to be sure it's up to spec. 
It might actually be above spec. I'm using a 60 amp rated Delco that has 
tested to produce 76 amps at 2000 rpm (and am upgrading wiring to handle it!) 
In 
case you are unaware, most auto parts stores are set up to quickly test an 
alternator on a bench. Many also have in-car testing equipment so you don't 
need 
to remove the alternator from a running car. Most offer the service free.

A 16" fan is a bit of overkill. 12" is the usual TR installation, plenty of 
air volume for a 2.5L engine in normal state of tune. I've installed a 14" for 
a more hotted up engine, and it's even a little more than necessary, moving 
1700 cfm. This 14" fan draws just under 10 amps. 

Another concern might be clearance. Check carefully. Many 16, 14 and even 12" 
fans would not fit on my TR4, in the puller location behind the radiator, due 
to slim clearance between radiator and the crosstube that braces the 
spring/shock towers. An especially "thin" fan has only about 1/4" clearance on 
my car, 
with the radiator as far forward as possible (but more space would be 
possible, if needed, by removing the radiator and slotting the mounting holes a 
bit).

Hope this helps! 

Alan Myers
San Jose, Calif. 
'62 TR4 CT17602L 

 I noticed that some of the 16" fans
drew a fair amount of current.  I have changed my alternator over to a Bosch
unit that puts out 55 amps or so, but is a fan that draws 13-17 amps an
issue I should be worried about?

R. Ashford Little II




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