Re: My week with Linux: I'm dumping Windows for Ubuntu to see how it goes

Notice that a gasoline with higher octane number allows the air-gasoline mixture to be compressed more, which makes the motor produce more power.

Possibly increasing the spark advance also increases the power yield, I don't know for sure.

Why do you have to insult people that simply do not know something?

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Years ago, it was often marketed that the Premium also had better additives. Today, Top Tier brands are the way to go.

In my Sonata with turbo, regular works fine, but just a half tank of 89 gives me better pedal feel. It is around town that I like it, on the highway no difference. Seems to help with the turbo as it spools up.

I've played with the a few times, depending on when I fill, I alternate to keep a slightly higher octane. I'd never bother with the 93. On my Genesis, non-turbo, straight 87 was good.

No. If the engine cannot utilise the increased knock resistance of the higher octane fuel, the benefit will be wasted. In an engine that has adaptive spark and knock sensors, it is possible that the ignition timing can be advanced thereby altering the point of MBT - but don't count on it. The point of MBT is pretty well defined on the original octane fuel. You may also find the engine runs more smoothly on a higher octane fuel - but there will likely not be any advance on power. Increase the compression ratio of the engine and then you will be talking. Also, you can increase the *static* compression ratio or you can increase the *dynamic* compression ratio. The dynamic (also known as effective) compression ratio directly relates to volumetric efficiency.

We have 3 levels of octane (RON) rating here 91, 95 and 98. 98, the premium fuel, has a higher detergent rating so will keep injectors cleaner.

My main point is that everything we think we know, is wrong. My second point is that everything we think we know was fed to us.

We didn't formulate any ideas on our own. Which is the problem I decry.

That's why I initially brought up gravity. Everything anyone (save for a physicist) thinks they know, is wrong.

Even something as simple as gravity being a force - is wrong. Likewise, orbiting astronauts are weightless in "zero gravity" - is wrong.

Higher-octane fuel being "better" because it costs more - is wrong. Even bread/milk on a gob'ment dietary-requirement chart - is wrong.

Choosing ceramic over NAO or semi-metallic - is also wrong - but you have to understand why it's wrong as there's nothing wrong with the materials.

People only know the marketing, where simply putting a spec of dust into a brake pad allows the marketing to claim good/better/best but it's wrong.

They don't understand anything about the product. People only know what marketing has fed them to believe.

A classic case is Apple happens to have the absolute worst hotfix support in the industry and yet most people believe that it's by far the best.

Who could possibly be that stupid? I assess only one out of a million people can cut through the marketing.

It bothers me that marketing is mostly lies that stupid people believe. It bothers me how much money these companies make out of stupid people.

I agree with Ed Pawlowski that there are highly marketed additives such as polyetheramines (some known by a specific brand name "Techron") which are nothing more than soap for gas whose patent expired long ago so now everyone has them, even Costco (which is what Top Tier brands use).

This Techron garbage is classic marketing where what people think they know is wrong, since, as Ed mentioned, it has nothing to do with the octane rating and worse - it's not even something special anymore.

But people "think" that premium fuel cleans better - yet it's just another marketing l/xl/gxl bronze/silver/gold easy-for-people-to-choose numberline to give people who are stupid a way to justify why they pay more for their gasoline than intelligent people pay.

As an aside, I once called up the parent company of "Chevron" to ask what Techron really meant, and they told me it means whatever they want it to mean - which - after all - is the most honest answer I've ever gotten.

Trademarks don't have to mean anything. Hence, they're used to mean whatever the company wants them to mean.

What they want it to mean is "better gas" but only stupid people think that. And yet, Chevron makes a lot of money off of stupid people, don't they.

While the octane rating is calculated and measured (and then averaged) here in the states, it's ultimately based on the knock propensity of two fuels. a. 2,2,4-Trimethylpentane (which is assigned an octane rating of 100) b. n-Heptane (which is assigned an octane rating of 0)

In the USA the octane rating displayed at the pump (the Anti-Knock Index or AKI) is the average of the RON and MON values, often written as (R+M)/2.

A. Research Octane Number This test is conducted at lower engine speeds and temperatures, simulating city driving or mild acceleration. B. Motor Octane Number This test is performed at higher engine speeds and temperatures, simulating highway driving or more severe operating conditions.

Any association with polyetheramine detergents is merely a marketing ploy.

which modern engines do, and I refer to those

So was I. Pretty much everything has knock sensors these days and most are adaptive. The ignition base timing map is calibrated to the rated fuel octane, engine load and engine RPM. If you fill with a lower octane fuel, the knock sensors will detect any knock and back off the timing. If you fill with a higher octane fuel, the ECU has no way of knowing the fuel is different so will continue to use the basic ignition timing map. As an example, my car is rated for 91 RON fuel. If I fill with 95 RON, the EMS has no way of detecting the change so will retain the same basic ignition timing map. On the other hand, if my car was rated for 95 and I filled with 91, the knock sensors would tell the ECU to back off the timing. That would affect the adaptation and the EMS would create a new timing map on the fly. That will mean the ignition timing will no longer be optimal to give MBT. The greater problem is - the EMS will keep the ignition right on the hard edge of detonation and, long term, that won't be good. Note, the knock sensors need to sense actual detonation before they react. So, with the lower octane fuel present, there will always be a tendency to knock. Note too, there are two ways to deal with knock. The obvious one is to back off the ignition timing. The other is to provide fuel enrichment. This occurs because the excess fuel cools the flame front, preventing it from reaching peak temperatures.

Xeno knows more than I do about this but it's my understanding that the best possible 'efficiency' (which I think he's calling maximum brake torque) is when the engine timing is such that it's on the very verge of knocking.

Note that almost all the time, you're nowhere near the verge of knocking, as it only happens, in normal sedate driving, at times of high load or acceleration or very high heat (which is an abnormal condition usually).

I've run many experiments on my bimmer which said it required premium, where I never "heard" the knocking but more importantly - I never could measure (with the crude methods available to me) any loss in MPG calculations.

Of course, real MPG calculalations are usually done by before and after weighing a plastic bag of a known quantity of test fuel - so we'll NEVER be able to ascertain any difference in fuel economy by our crude methods.

Which is a key point....

1. You can pay 10 cents more per gallon every fillup of your life to achieve a performance & economy of X... or...
2. You can pay 10 cents less per gallon every fillup of your life to achieve essentially the same performanc & economy.

Point being, the word "always" in Xeno's statement, I think is wrong.

Hence, while I defer to Xeno's knowledge, it's my personal assessment that you'll ONLY knock under high heat/load situation which, depending on how you drive, will almost never happen for most people who aren't racing.

You mean that the system is so stupid as not to recalibrate each time you fill the tank?

Are all cars like this?

No. All systems are constantly adaptive. They don't know or care when the tank was filled.

Maximum brake torque isn't the same as engine efficiency but they are correlated so we'll take that as close enough.

Yes, and that is why car engines are so inefficient and why hybrids have such an efficiency win; the engine is designed for maximum power but seldom operates at that regime.

Contrast this with an aircraft engine that is usually being operated at close to full throttle all the time. (Admittedly the aircraft engine allows the pilot or flight engineer to adjust the mixture control to keep it always lean for efficiency but not too lean that it knocks. Some allow fine timing adjustments too.)

Try that on a 2002 and you'll hear the knock and likely feel a pain in the pocketbook for the valve job.

--scott

Not only is the date encoded in the serial number of all USA passenger tires, but the traction, treadwear and temperature (aka speed) of the tire is embossed on the side.

So is the size (of course) and type (e.g., light truck or radial) and so is the load range (which is one of the most important specs on every carcass).

Also embossed on the sidewall is the speed (which is separate from the temperature but which is essentially the same metric done a different way).

But how many people can "read" a tire?

I would wager 999 out of 1000 people simply choose tires by whatever marketing bullshit is fed to them by the tire salesman. Prolly' they buy tires based on warranty as that's an easy "number line" to choose from.

But if you read a tire, you can easily choose a good tire from a less good tire (they're all good - but some are more good than others) by the specs.

If there's a tie between two tires of the same specs (which almost never will happen), then by all means break the tie based on the marketing warranty.

For those who know how to buy tires, how does this process sound to you?

1. Look at the tires on the car already
2. If you like them - then by all means - buy the same tires
3. But if you don't care and if you're doing a set - then get new ones

a. First figure out the factory specs (speed, load range, size range, etc.) b. Then limit your search to NOTHING BELOW those minimum specifications! c. Find the best combination of the factors listed above you care about

Then get the tires that meet your minimum spec at the lowest possible cost. In general, if you mount the tire yourself, the only extra cost is tax.

Most shipping is free to your home (or to a tire shop). Mounting and balancing at home is free also (but only after about 10 years).

If you don't plan on living more than ten years, then it's probably not worth the $300 or so in investment in the tire-changing & balancing tools.