Dyno wrote:
> Inlet Pr Atmospheric <-----WOT!
You are talking about a naturally aspirated one cylinder engine with a
carburetor attached to a very narrow intake manifold. The pressure,
temperature
and humidity of air entering the engine is carefully controlled so that
daily
variations in atmospheric conditions don't skew the results. This has
nothing to
with WOT. The ASTM literature claim the test is designed to simulate mild
operating conditions. They characterize the load on the engine as light.
> Again you confuse speed with load. They are not the same.
You are the one that is confused. The engine operates with below
atmospheric
pressure in the intake manifold and that limits engine speed. The load on
the
engine is light.
> What is absurd is your willingness to disregard the body of published
> information on this subject (and there is plenty).
>
I'm ignoring your misinterpretations
> The octane rating of any fuel is only used to rate the propensity of the
> fuel to detonate. It does not indicate the heating value of the fuel
> itself.
There actually is a fairly consistent negative correlation between octane
and
heating value in most motor fuel components so actually your wrong aboutr
that.
But your assumption that heating value alone determines fuel economy is
also
incorrect.
>This is easy to see. Commercial fuels are sold with octane
> ratings of 87 and 93 (pump ratings). Yet both fuels have heating values
> within a couple percent of one another. Another example, methanol has
> (R+M)/2 = 109, yet has half the heating value per kg as gasoline. The
> octane rating does not correlate with the energy in the fuel.
No, with almost all constituent components of motor fuels it negatively
correlates, but that is also beside the point as it doesn't really say
anything
about octane and fuel economy.
> >
> If the engine does not detonate at a particular operating condition, it
> does not matter what the fuel's octane rating is. It was sufficient to
> preclude abnormal combustion.
Sure just keep repeating your mantra over and over and maybe you someday
you
will achieve enlightenment.
Your point isn't incorrect - it just doesn't shed any light on the
relation****p
between fuel economy and the tendency for a particular fuel in a
particular
engine to detonate.
If a load of fuel and air exhibits no detonation at all then that is a
good
indication that some of the energy that could have been converted to
mechanical
power failed to convert (it's wasted). How much power goes to the wheels
is a
function of how much pressure can be applied to the pistons over the
proper
period of time. The most significant limit to this pressure integral is
detonation. Detonation and the measure of fuel to resist detonation is far
more
im****tant than the energy content of any particular fuel because most of
that
energy content ends up being wasted.
In other words, Octane has everything to do with fuel economy.
-jim
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