RE: [alfa] smaller alternator

[Jon Pike <jhpike@xxxxxxx>]

Hmmm... I'd think that the average current should go up,  and with a CD 
type ignition system it surely does..  but the basic points style has 
the points closed (and max current flowing) for the majority of the 
time.  Remember it's the change in current that creates the spark, the 
sharp opening of the points.  So, unless the dwell angle changes somehow 
it should be about the same,  or maybe increasing somewhat due to the 
number of charge/discharge cycles per second increasing.  Maybe it even 
decreases..

Thing is,  it's not that much, in proportion to horsepower..  What's the 
fuse on the coil circuit, and how much lower than that is the running 
current?  Not sure off the top of my head, but I'll bet it's a 8A,  if 
it's the only thing on that circuit...

Let's look at the power requirements of the alternator,  at max load.  
Let's see,  mine is:
12V @ 55A.  12V X 55A = 660W.   746W = 1HP.  So, 660W = .88HP,  then say 
the alternator is 80% efficent,  we're back up to 1.1 HP required for a 
full 55A load.   I have no idea how much physical work HP it takes to 
spin up the alternator, bearing drag, belt drag, etc..  but it would 
seem that going from 0-55A load only adds a HP or so extra.  And,  you 
probably never pull the full 55A with everything on in the car.. 
I'd guess there's probably lots more HP eaten by the fan at high RPM... 
So 1-2 HP maybe..  if you are racing,  and lightened so that each HP 
feels stronger.. and you're after 1/10ths of seconds... sure, take the 
whole dang thing out and run on battery!  But for street, it's probably 
not very noticable.  Get rid of the mechanical fan,  put in an electric 
with maybe a 1/4 to 1/2 HP loading on the alt when it runs,  and you're 
probably way ahead of the game.

Uh, IMHO.. 
Jon


> Doesn't the ignition system require the higher voltage/current that is supplied by the alternator especially at higher loads and rpms???
> jeff
> 77 Spider
>
> Ed Lutz <edlutz@domain.elided> wrote:
> Its a somewhat common thing with serious street racers to have a alternator 
> cutout switch which takes the alternator out of the circuit all together. 
> It works.
>
> Ed
>
> At 04:37 PM 11/8/2004, White Anthony wrote:
>  
>
> > > Joe wrote:
> >    
> >
> > > > > Now that I've given this some thought, I'm inclined to question the
> > > > > alternator issue.
> > >      
> > >
> > > I understood Dr Tenney recommended gutting the alternator entirely, and then
> > > running the engine from the battery.
> > > Race only option, of course.
> > >
> > > Anthony White
> > > Wellington, NZ
> > > --
> > > to be removed from alfa, see /bin/digest-subs.cgi
> > > or email "unsubscribe alfa" to majordomo@domain.elided
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided