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Re: Power Upgrades- Alternators and Fans

To: Triumphs <triumphs@autox.team.net>
Subject: Re: Power Upgrades- Alternators and Fans
From: "Power British Performance Parts, Inc." <britcars@powerbritish.com>
Date: Sun, 14 Mar 1999 09:56:41 -0500
References: <199903140915_MC2-6DE9-8A79@compuserve.com>
Tony Rhodes wrote:

> >Correct me if I'm wrong (yeah, right, like I have to ask!).
>
> Dan, I think you are right on target.  Probably optimistic a bit on efficiency
> of motors and generators.  30% sticks in my mind....
>
> I agree that on the face of it, an alternator (or generator) should
> only suck up a small amount of power.  Maybe I don't understand the
> effect of a little extra load on idle speed, but when I take my 4 liter
> V-8 and suddenly load it with a seat heater and a rear window defroster, the 
>idle
> drops considerably until the computer catches it (about 1/2 to 1 sec) and 
>raises
> the idle speed a tad.  Also interesting to see the voltage drop a lot in that
> time and then re-stabilize at the 15.3 I usually see.
>
> Does the added load of one HP really drop the idle that much?  Must be...
>
> Another issue this raises.  Once I was in the market for the accura integra.
> At that time, in an effort to wring the maximum HP, they put a clutch
> on the alternator (like the AC) and with the throttle wide open, the engine
> stopped spinning the alternator and AC compressor!  It seems to me that if the
> alternator load is so minimal, it is not worth the complexity and expense
> of adding the clutch.
>
> What do you think?
>
> -Tony

I think an important note to make here is that at idle, an engine is only 
making 10
maybe 15 horsepower.  You don't get to 104hp until 4,500 rpm.  If the alt. 
places a 2
hp load on an engine making 10-15 horsepower, that's a big percentage and 
you're going
to see a drop in rpm for sure.

Regards,

Brian Schlorff    '61 TR-4     '64 TR-4     '72 TR-6     '79 Spit
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