engine accessories

Has anyone a best guess figure for the power used in running engine
accessories, is it likely to be just a couple of hp each for the
alternator, a/c, power steering, water pump.

Thanks
Smokeyone

I've seen mustangs pick up 15 RWHP by removing the AC, PS, and adding
an electric WP

> wrote
> Has anyone a best guess figure for the power used in running engine
> accessories, is it likely to be just a couple of hp each for the
> alternator, a/c, power steering, water pump.

Well, a typical alternator is 14 volts, 50 amps, which is 700 watts.
That's almost a hp (746 watts per hp).

The most power-soaking accessory is the a/c compressor, which
is usually in the 5-10hp range. The other accessories are probably
in the same range as the alternator, although the water pump doesn't
take as much and the power steering may (it's not a continuous drain
remember) take more.

Floyd

"fbloogyudsr" > wrote in message
...
> > wrote
>> Has anyone a best guess figure for the power used in running engine
>> accessories, is it likely to be just a couple of hp each for the
>> alternator, a/c, power steering, water pump.
>
> Well, a typical alternator is 14 volts, 50 amps, which is 700 watts.
> That's almost a hp (746 watts per hp).

That's only when it's putting out 50 amps, if it's putting out less, there
will be less resistance against the engine. It would also be more than 700
watts required, because it isn't 100% efficient. Also, aren't typical
alternators these days rated higher? 75-100 amps?

> The most power-soaking accessory is the a/c compressor, which
> is usually in the 5-10hp range. The other accessories are probably
> in the same range as the alternator, although the water pump doesn't
> take as much and the power steering may (it's not a continuous drain
> remember) take more.

I agree, A/C is the biggest user.

I've also seen some people gearing their accessory belt to turn slower, to
improve the performance of their engine.

Bill 2 wrote:
> "fbloogyudsr" > wrote in message
> ...
> > > wrote
> >> Has anyone a best guess figure for the power used in running
engine
> >> accessories, is it likely to be just a couple of hp each for the
> >> alternator, a/c, power steering, water pump.
> >
> > Well, a typical alternator is 14 volts, 50 amps, which is 700
watts.
> > That's almost a hp (746 watts per hp).
>
> That's only when it's putting out 50 amps, if it's putting out less,
there
> will be less resistance against the engine. It would also be more
than 700
> watts required, because it isn't 100% efficient. Also, aren't typical

> alternators these days rated higher? 75-100 amps?
>
> > The most power-soaking accessory is the a/c compressor, which
> > is usually in the 5-10hp range. The other accessories are probably
> > in the same range as the alternator, although the water pump
doesn't
> > take as much and the power steering may (it's not a continuous
drain
> > remember) take more.
>
> I agree, A/C is the biggest user.
>
> I've also seen some people gearing their accessory belt to turn
slower, to
> improve the performance of their engine.

I'm not sure I understand the purpose of doing this... I'm running a
Delco 12SI alternator on my '55 Stude which has only a minimal current
draw when the engine is running (i.e. all that is really active is the
coil and two gauges if nothing is manually turned on) and at the
factory-specified 550 RPM idle, the alternator is barely keeping up.
If the idle fluctuates a bit, you can see the ammeter needle wiggle.
I'm considering going to a *larger* alternator pulley if I can find
one. Getting stuck in traffic after dark or in the rain and draining
your battery sucks.

Or do more modern vehicles tend to idle at a higher speed? The crank
pulley looks to be about the same size as I'm used to seeing on more
modern vehicles. (It's actually a '63 Stude V-8 under the hood)

nate

"Jack VR4" > wrote in message
ps.com...
> I've seen mustangs pick up 15 RWHP by removing the AC, PS, and adding
> an electric WP
>

And the electric water pump gets its power from ??? couple in an electric
fan and a few other accessories and you'll need a bigger alternator.

Snow

Set the idle up a bit, or if you want to be really old fashioned put a
hand throttle in.

On a small car, the amount of power lost to power accesories and steering
can be quite large. The power steering on a small car can increase the
fuel consumption by about 5 percent, and A/C is about the same or greater.
It all adds up, though.