N8N wrote:
> On May 7, 11:11 am, jim <".sjedgingN0sp"@[EMAIL PROTECTED]
> wrote:
>> Dyno wrote:
>>
>>> jim wrote:
>>>> Dyno wrote:
>>>>> Jim,
>>>>> Octane rating has very little to do with fuel economy. Performance,
yes.
>>>> Having AF ratio designed to maximize efficiency in the catalytic
converter
>>>> doesn't have much to do with fuel economy. When fuel economy starts
to
>>>> really matter the catalytic converter is going to be replaced with
systems
>>>> that burn the fuel inside the engine and deliver it to the wheels.
And
>>>> octane will matter.
>>>> -jim
>>> Seeing as how 99%+ of the fuel already IS burned in the engine, I
don't
>>> agree with your assertion.
>> Burning the fuel and using the energy as opposed to shooting it out the
>> back at the guy behind you are 2 completely different things. The
average
>> car engine is using less than 30% of the energy in the fuel so talking
>> about the total energy contained in the fuel as if all of it is being
used
>> is a complete absurdity. If you want to talk fuel economy in a serious
way
>> you need to look at the 70% that is trailing behind every automobile
>> rather than focusing on whether a particular fuel has 1% more or less
>> energy.
>
> You *do* need to account for the energy content of the fuel, because
> even assuming that your engine is tuned to use the exact A/F ratio for
> every fuel that goes into it the overall efficiency of the engine
> itself does not change in any significant manner, so the fuel with the
> higher energy density will yield higher MPG.
>
>> The fact is that the catalytic converter is part of a design
that is
>> consuming additional fuel - not because of the small amount that is
burned
>> inside it but because of the constraints it places on the entire design
>> that limits efficiency.
>
> Huh?
>
>>> Octane rating is related to the susceptibility of the fuel to
>>> auto-ignition.
>> Well that is a very naive and simplistic view of a very complex
subject.
>> The fact is that almost any gasoline powered car on the road will get
>> better fuel economy if you start fueling with aviation gas.
>
> False. In fact, the opposite may be true, although to such a small
> degree that it's hard to say for sure one way or another.
>
>> Why is that?
>> The issue of fuel economy and octane can't be reduced to a platitude
and
>> one simple number on a pump. Gasoline is not a single chemical with
>> simplistic properties its a complicated mix and that mix is constantly
>> changing.
>
> That much is true, but there is absolutely *no* advantage to using a
> higher octane fuel than the engine is optimized for.
>
>> Motor fuel is not designed for the cars. It's designed for
maximizing
>> profits. And cars are designed for maximizing profits. Lead was used in
>> gasoline not because it benefited you car but because it benefited the
oil
>> companies bottom line.
>
> No, TEL was used because it was a cheap and cheerful octane booster,
> allowing fuel companies to sell higher octane fuel without a
> significantly higher cost. It also offered other benefits like
> exhaust valve/seat protection. This allowed mfgrs. to offer more
> efficient engines with higher compression ratios once TEL-enhanced,
> higher octane fuels were available.
>
>> MTBE was mandated not because it benefited your car
>> or your pocket book or your environment - it was mandated because it
>> benefited the oil industry. The EPA estimates it will cost 3 billion
>> dollars to clean up and remediate the damage done to the environment by
>> MTBE. And obviously when the work is actually done it will cost a lot
>> more. And of course you will pay for it because the oil industry can't
be
>> held responsible because they were told by the government to use MTBE
>> instead of lead.
>
> Now that much is plausible, the MTBE thing does smack of policy set by
> politics.
>
>> And this was all done for octane which you claim has
>> nothing to do with fuel economy.
>
> Octane *does* have nothing to do with economy, once you are talking
> about octane ratings higher than that for which your car's engine was
> designed.
>
>> But with fuel headed to $10 and $20 a gal. The driver might
actually
>> start having some say in the process. When the purchasing habits change
>> the motivation is also going to change significantly.
>>
>>> This is generally most significant at high-load operating
>>> conditions.
>> No. Octane and fuel economy are heavily intertwined.
>
> No, they're not.
>
>> The government and
>> the oil companies would prefer you do not look to closely at that fact
-
>> because it's money in their pocket and not yours. Octane ratings are
based
>> on both high load and light load testing and it is nowhere near an
exact
>> science nor are the constituent properties of the fuel constant - they
>> vary a lot with time and place. But more im****tant fuel economy is what
>> you pay per mile and for starters that price on the pump has everything
to
>> do with octane.
>
> Of course higher octane fuels are more expensive, but that doesn't
> affect you if you don't need the higher octane.
>
>> Did you know that the oil refineries call it "octane give away"
if they
>> ****p a fuel that is 0.1% higher in octane than it is legally required
to
>> be. Giving the public .1% higher than it needs to be octane can cost a
>> large refinery 20 million dollars a year. And you claim it has nothing
to
>> do with fuel economy.
>
> That's right. It has nothing to do with fuel economy. Of course the
> oil co's don't want to make fuel a higher octane than it needs to be,
> because higher octane fuels are more expensive to produce. That's why
> they charge more for them.
>
>> The oil companies, car manufactures and government are not
interested in
>> fuel economy. No one cares how much your personal trans****tation costs
>> other than the driver and many of them apparently don't care either.
Today
>> the government is asking you to respond to higher gas prices by driving
>> more - they might as well ask you to slit your own throat. Increased
fuel
>> consumption will only drive the price of fuel higher. The entire system
>> from top to bottom is designed to use more fuel and for the most part
>> people like you just go with the flow and don't question any of the
>> platitudes handed down from above. It's only when consumers will stop
>> buying it that things will change.
>
> OK... so what does this have to do with octane?
>
>>> When I think of fuel economy, I think of light-load operation;
cruising
>>> down the highway or driving around town. On a time-weighted basis,
under
>>> these conditions engine loads (BMEP levels) are relatively low. It is
>>> also at these conditions that the octane requirement is also low.
>> No, incorrect, if you want to maximize fuel economy, the RON
requirement
>> is high under light loads. But your fuel supplier isn't telling you
what
>> the RON in the fuel you are using is. So you have no way of knowing how
>> the octane in your fuel affects your fuel economy.
>>
>>> Increasing the octane rating of the fuel will not alter the energy
>>> inherent in the fuel nor will it boost fuel economy.
>> That belief is how fools are parted with their money.
>
> No, it's fact.
>
>> They would like you
>> to focus on the inherent energy in the fuel. Octane has everything to
do
>> with how the oil companies make their money off you. Octane has
everything
>> to do with how an engine and its fuel can be designed to maximize fuel
>> economy. The only hope is that as prices skyrocket that fuel economy
will
>> become a real issue, instead of a shell game, The realities of octane
are
>> going to have to be addressed head on rather than hidden as they are
now.
>
> I'd suggest you do a little more research before posting incorrect
> wild conjecture as fact. Or, if you're going to make claims that
> contradict what most educated people believe to be the case, at least
> provide some sup****ting do***entation for your assertions.
>
> nate
Thanks, Nate!
I was all set to fire off a followup, but you beat me to it, almost
point by point. A lot of the nonsense that gets posted could easily be
avoided is some posters would simple go buy an engine text book and
simply browse through it.
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