Today's Message Index:
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1. 11:50 AM - Franklin Versus Lycoming (flyseaplane)
2. 12:31 PM - Re: Franklin Versus Lycoming (Tedd McHenry)
3. 01:16 PM - Re: Franklin Versus Lycoming (Tedd McHenry)
4. 04:07 PM - Re: Franklin Versus Lycoming (albert piccioni)
5. 05:00 PM - Re: Franklin Versus Lycoming (Tedd McHenry)
6. 08:36 PM - Re: Franklin Versus Lycoming (albert piccioni)
7. 09:55 PM - Re: Franklin Versus Lycoming (Tedd McHenry)
Message 1
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| Subject: | Franklin Versus Lycoming |
--> Engines-List message posted by: "flyseaplane" <flyseaplane@netzero.net>
"Both engines rated 180 hp., both normally aspirated and carbureted. The
Franklin 6A-335 B is 6 cylinders, 334 cubic inch, 7:1 compression, 2800 rpm
red line. The Lycoming O-360 is 4 cylinders, 361 cubic inch, 8.5:1
compression, 2700 rpm red line."
There are several factors involved:
1) You can not actually "measure" Horsepower, it must be mathematically
derived by multiplying Torque (X) RPM and dividing by 5252 ( a constant)
If the Franklin makes the SAME EXACT torque as the Lycoming, but at a higher
RPM, it will automaticly have more horsepower.
2) The manufacturers may rate the engine by different testing means. Perhaps
the Lycoming makes 180 HP with the alternator running at full charge,
spinning a vacuum pump, running through a muffler and sucking through an air
filter. The Franklin may be bolted to the dyno with no accessories to rob
power.
3) No two dynos produce the same exact readings. Repeat that several times.
4) Maybe Lycoming is assuming a worst case scenario, and Franklin is
assuming best case. Everybody I have ever spoke to that has dynoed their
"stock" Lycoming has said it made more power than it was rated at. A good
friend of mine dyno'ed his Lycoming O-290-D2 (135 HP rated) at 143 HP. Eight
more horsepower is a nice margin of error, that way you can guarantee you
will get 135 out of it at most times, even when it is getting close to TBO.
I would like to see both engines side-by-side on the same dyno. That would
settle all wondering.
Lincoln E. Schlecht
EAA Tech Counselor #4434
Message 2
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| Subject: | Re: Franklin Versus Lycoming |
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
I get the strong sense that some people are trying to make excuses for Lycoming
here. Both engines are certified, and both manufacturers are stating their
rated power. A dynamometer is just an instrument. The measurements of two
different CALIBRATED dynamometers are not going to give significantly different
measurements, once corrected for atmospheric conditions. And those corrections
are standardized by the SAE test (both companies quote SAE power), as is the
use of auxiliaries. And the argument that power is calculated, not measured,
is pure moonbat. It's like saying if I measure a board with a tape measure
that reads in feet and you use one that reads in inches we'll each conclude
that the board is a different length. It's nonsense. X foot-pounds of torque
at Y RPM is Z horespower, period; it does not matter whose dynamometer it's
measured on or who does the calculation. So there's no reason whatsoever not
to take the power ratings at face value.
I think a lot of people are still confused from the days before power tests
were standardized, and manufacturers used to do all sorts of things to make
their power numbers look better (such as disconnect all auxiliaries, including
the water pump). Those days are long gone.
Tedd McHenry
Surrey, BC
Message 3
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| Subject: | Re: Franklin Versus Lycoming |
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
> And the argument that power is calculated, not measured,
> is pure moonbat.
Sorry, that looks like I'm saying Lincoln's argument is "moonbat," and that's
not what I meant. Lincoln is right that the same torque at a higher RPM yields
more power. I was dragging in another argument out of context.
Tedd McHenry
Surrey, BC
Message 4
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| Subject: | Re: Franklin Versus Lycoming |
--> Engines-List message posted by: "albert piccioni" <adpiccioni@cnx.net>
Simply put,,,,to settle this thing in peoples minds,,,,,,we can MEASURE
torque to calculate H.P.
We cannot MEASURE H.P. to calculate TORQUE
alberto,,,,,in the okanagan,,,,muggy day here today
----- Original Message -----
From: "Tedd McHenry" <tedd@vansairforce.org>
Subject: Re: Engines-List: Franklin Versus Lycoming
> --> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
>
> > And the argument that power is calculated, not measured,
> > is pure moonbat.
>
> Sorry, that looks like I'm saying Lincoln's argument is "moonbat," and
that's
> not what I meant. Lincoln is right that the same torque at a higher RPM
yields
> more power. I was dragging in another argument out of context.
>
> Tedd McHenry
> Surrey, BC
>
>
Message 5
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| Subject: | Re: Franklin Versus Lycoming |
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
> Simply put,,,,to settle this thing in peoples minds,,,,,,we can MEASURE
> torque to calculate H.P.
> We cannot MEASURE H.P. to calculate TORQUE
At the risk of flogging a dead (or at least dull) horse, that's not true. We
measure torque directly and from it calculate power because it's more
convenient. But we could just as well go the other way by, for example, using
the engine to raise a 550-pound weight and measuring the speed in feet per
second to get a direct measurement of horsepower. We could then take that
number and divide by rotational speed and the appropriate constant to get
foot-pounds of torque.
Saying that torque is measured directly whereas power isn't tends to imply that
there's something vague or misleading about power, or that torque is somehow a
more meaningful measurement. Those assertions aren't true, either.
Tedd McHenry
Surrey, BC
Message 6
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| Subject: | Re: Franklin Versus Lycoming |
--> Engines-List message posted by: "albert piccioni" <adpiccioni@cnx.net>
Not so,,,what you say has been tried and found unsatisfactory,,,,,,the
system you advocate uses too many items that introduce inconsistent
varialbles.
alberto,,,,in the okanagan
----- Original Message -----
From: "Tedd McHenry" <tedd@vansairforce.org>
Subject: Re: Engines-List: Franklin Versus Lycoming
> --> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
>
> > Simply put,,,,to settle this thing in peoples minds,,,,,,we can MEASURE
> > torque to calculate H.P.
> > We cannot MEASURE H.P. to calculate TORQUE
>
> At the risk of flogging a dead (or at least dull) horse, that's not true.
We
> measure torque directly and from it calculate power because it's more
> convenient. But we could just as well go the other way by, for example,
using
> the engine to raise a 550-pound weight and measuring the speed in feet per
> second to get a direct measurement of horsepower. We could then take that
> number and divide by rotational speed and the appropriate constant to get
> foot-pounds of torque.
>
> Saying that torque is measured directly whereas power isn't tends to imply
that
> there's something vague or misleading about power, or that torque is
somehow a
> more meaningful measurement. Those assertions aren't true, either.
>
> Tedd McHenry
> Surrey, BC
>
>
Message 7
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| Subject: | Re: Franklin Versus Lycoming |
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
> Not so,,,what you say has been tried and found unsatisfactory,,,,,,the
> system you advocate uses too many items that introduce inconsistent
> varialbles.
Alberto:
Your statement was...
> > > We cannot MEASURE H.P. to calculate TORQUE
I wasn't proposing that measuring power directly was the best way, I was simply
pointing out that your statement above was not true. It quite clearly IS
possible to measure power directly, as I described, and in fact that is how
horsepower was originally defined.
But the entire issue is silly since, strictly speaking, we don't measure torque
directly, either. We measure volts, the output of the piezoelectric cell
attached to the dynamometer. Then we calculate torque from that (in most cases
the dynamometer calculates it for us). Then we calculate power from that.
Tedd McHenry
Surrey, BC
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