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From: John De Armond
X-Source: The Hotrod Mailing list
Date: Apr 1992
Subject: Re: Auto Trans.

>I have to be more than a little bit suspicious about an article that
>says you lose 60 HP in a T400.

You're not the only one.

>An old article in one of the hotrod build-it books says that they
>chassis dynoed a car with a manual trans and later with an automatic
>and found less than 5 HP difference in power.

I'd believe that.

>Another thing to consider is heat - if the trans really did burn 60 HP
>then that is about 45 KW of heat to get rid of - where could it go?
>A bathroom heater puts out about 1.5 KW of heat so the alleged tranny
>losses are 30 bathroom heater's worth.  Not credible.

Further, if I converterd the numbers from my reference correctly,
gasoline makes about 24.6 kw-hr per lb.  In other words, we'd
be burning about 2 lbs per hour just to heat the transmission.
Not very credible at all.

>Some of the writers for the car mags don't show evidence of understanding
>simple, basic physics and engineering principles.  Take their writings
>with a grain of salt.

Glad to see I'm not the only one to notice that.  Another one I get
a real kick out of is the claim that an alternator consumes 5 or
10 or 20 or you-name-it horsepower.  Anyone ever seen a 5 hp continuous
duty motor?  Wonder how many alternators would fit inside one?
Some hard data.  I have a prototype of a nifty little 11 lb cordless
battery charger here that will become a product someday.  This thing
consists of a 2 hp weed whacker engine, an alternator and some
custom controls.  I designed this thing for drag racers and others
who need to rapidly charge a battery away from electrical outlets.
This thing generates 60 amps (alternator's limit, not engine's).
The alternator is directly driven at the two stroke's 5800 rpm peak
power point.

Then there's windage loss.  Some claim that one has to pop the
alternator belt off before running at the strip.   Turning the
field off is not enough.  Supposed to save, well, billions and billions
of horsepower.   I've looked at this from two angles.  One, I've
instrumented the govenor on the engine and two, I've measured
fuel consumption.  Neither show any difference to the resolution of my
instruments with or without the freewheeling alternator connected.
'Nuff said.


From: Dan Malek <emory!gatech!!dan>
X-Source: The Hotrod Mailing list
Date: Oct 1993
Subject: Re: Switch to turn off Alternator 
X-Sequence: 6589

> Date:  Thu, 23 Sep 93 18:25 EDT
> From:  emory!!tcullen (TARY M. CULLEN)

> will loose that 
>extra .001 of a second.  Good Luck, every little bit helps.

>[Let me scale this for everyone.....
>.........  Figure in the efficiency
>and 1.5-2 hp still is more than enough to drive a standard alternator....
>...  JGD]

Before you disconnect the alternator, consider my discovery the other night.
We had a small block Chevy on the dyno with an MSD.  To supply power we
always use a fully charged battery, and leave the charger running to
produce 13.8 volts.  Well, the other night we forgot to turn on the charger,
and the engine was down about 17 horsepower.  The charger went back on
and the power came back.  We then began to experiment.  Anything less than
13.4 caused a significant power loss, more than 14.0 did not help.  Now,
these were not the most efficient combustion chambers because the racing
class required mostly stock parts, so they were very sensitive to MSD
ignition.  More efficient chambers are less sensitive to the MSD, but
it is still more than 2 HP.

You should check out the number of race cars, in all classes, that run
alternators.  You will be quite surprised how many use them.  When we
are looking for that extra 0.01 second, we make sure the alternator is

Ignition systems are power hogs and sensitve to voltage, especially the MSD.
Don't skimp when feeding them, it will really cost you.

	-- Dan

From: John De Armond
X-Source: The Hotrod Mailing list
Date: Aug 1992
Subject: Re: Underdrive Pulleys

>On the flow bench thread it was mentioned that you could check to see how
>inflated the underdrive pulley merchant's claims really are with some
>torque sensors.  Well, that tied in with a debate I'm currently having
>with a friend of mine regarding the underdrive pulleys.  So, what's
>everyone's opinion?  I have seen claims of 20 HP on a Buick V6 Turbo with
>the crank pulley alone (pure snake oil, IMHO).  I've also seen more
>realistic claims of 5HP ... however, I think it's Duttweiller who says he
>sees no difference on the dyno.  Again, I don't know as that really
>proves anything, since I would think it would be very difficult to
>measure small HP gains on the dyno reliably. Bottom line, IMHO?  Good
>hype and hoopla, but very little real gains in a street/strip
>combination.  The trade offs may include poor cooling and low alternator
>voltage.  I would think the real killer for the Turbo car is the low
>voltage, what with the ECM, all the sensors, high energy coil packs, high
>pressure electric fuel pump, injectors, power accessories, etc.

I think it is in general BS too.  A couple of datapoints.  I have the prototype
of a product sitting in my lab I call the Cordless Battery Charger.  It
consists of a 2hp weed-whacker-style engine and a physically small alternator.
It will generate up to 60 amps at 13.8 volts without fully loading the
engine, which is direct-coupled to the alternator and turns at 5800 RPM.
60 anps is 828 watts.  There are 746 watts to a horsepower so it becomes
obvious that even a gonzo 120 amp alternator is only going to use
a couple of HP and then only at full output.

What many people fail to comprehend with the alternator is that if you
slow it down, the voltage regulator will simply crank up the field excitation
to whatever value it takes to maintain voltage.  The mechanical effect
is the torque requirement rises as the speed decreases IAW
torque*RPM/5252 = hp.  Since watts are the same as hp, the alternator will
draw a constant hp to supply a given watt load.  The only difference
will be the very minor air drag difference.  On the Cordless Battery
Charger, I can't see the govenor lift at all when spinning an un-excited
alternator so the drag is trivial.

There was an article in Circle Track mag awhile back where Steward Pumps
build a water pump dyno to see what the story was on water pumps.  The
worst pump consumed about 20 hp.  His racing pumps were down around 8 hp.
(anyone see a big win?)  Underdriving MIGHT help IFF you have extra
cooling capacity AND can cool adequately at low speed (if you even need
to, of course.  Don't neglect the need to keep head temperatures as
constant as possible while assessing whether you have excess flow.

The deep groove pulleys such as the stock car guys use could be a reliability
benefit but not power.  Seems to me the money spent on underdrive pulleys
for the strip could be better spent on a reaction time simulator.

You are exactly correct that low voltage to the electronics is vastly worse
than the few fraction of a HP running without an alternator will deliver.


From: Keith Kucera <emory!!kkucera>
X-Source: The Hotrod Mailing list
Date: May 1993
Subject: Re:  Mustang
X-Sequence: 5268

I highly recommend swapping the stock mufflers for a pair of Walker
Dynomax Super Turbo Mufflers.  I tried both straight pipe and the
Walkers.  Straight pipe kills the low end torque and your ears at 1800
RPM (65-70mph).  The Walkers will give you a noticable power improvement
throughout the power band and only slightly increase sound.  And you
can't beat the price.  A local shop installed mine for a total price of
$75.  Most bang for the buck.

Next remove the intake silencer from inside the right front fender.
This is basically a muffler for the intake and supposidly gives 5-10 hp.
It takes some manouvering to get it out, but it'll come.

Next trick is to install a cooler thermostat.  Stock I think is around
180 or 190 degrees.  The local parts store has 160 degree thermostats.

[I would recommend against this unless you know why you're lowering the
engine temperature and how to evaluate the results.  Many but not all
engines make more power at higher temperatures. See this month's
"Circle track" magazine for a report on the GM restrictor motor that
does.  The engine management system may not like the cooler temperature
too and may never come out of cold enrichment.  JGD]

Another popular item is to replace your stock pullies with underdrive
pullies.  These are available from most speed shops.  These will cause
your accessories to turn slower, lessoning their parasitic drain on the

[I'd advise against this one too unless you know the specific problem
you are trying to fix.  Ford, in particular, is pushing the limit
with their alternators trying to reduce weight and drag in an effort
to improve CAFE.  I have documented a T-bird where the alternator
was too small to supply the load at low engine speed.  Ford patched over
the problem with a larger battery.  A week of stop-and-go traffic still
left his battery drained.  Before slapping a "trick" part on the beast,
make some measurements to see if it will work.  Measure the current
flow at idle and low speed with all the accessories and head lights on
and see if the alternator can keep up.  If it is marginal, slapping an
underdrive pulley on the thing will only make it worse.  Ditto with the
water pump.  I'd bet (without having actually measured it) that
the water pump is on the edge too, all for CAFE considerations.  JGD]

Handling wise, a must do is to slide in the front struts to achieve
maximum negative camber.  Raise the front of the car with the wheels off
the ground and loosen the three nuts on the top of each strut tower
under the hood.  You'll also have to remove the rivit.  Then slide the
top of the strut in towards the engine as far as possible and tighten
the nuts.  You'll notice this as soon and you enter the first hard
corner.  The car actually turns!!  I've seen as much as 1.5 degrees of
negative camber from this trick.  Make sure to have your toe set since
this trick will cause toe out (which is good for quick turn-in but bad
for straight line stability)

Happy Stangin

Keith Kucera

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