Fuel Octane

[RustyLugNut]

So you wish to say that the octane rating has absolutely nothing to with power or performance, CORRECT!

So, when you have 86 octane in a car and you drive on a regular basis. With a load and in our normal driving habits. When the cars engine begins to "KNOCK" from low octane under load and the computer adjusts the timing to compensate, which adjusts fuel usage to do so, it doesn't consume more fuel then if it were not doing so ????
Higher octane fuels will cause less "KNOCK" in the engine and provides less adjustment via the computer, so there for uses less fuel. AND this is not just my theory, but yet proven by the automotive industry.
When you have engine knock at any load you are doing many things that are not in favor of fuel consumption; higher cylinder temperatures, more negative emissions, and damaging wear on the engine! Even short term continuous knock is damaging to the exhaust system as well. Clogging of the egr valve, catalytic convertor, and a dirty intake to start!

When you see the puff of smoke come out the tailpipe when you accelerate or just give it gas in park, is excess gas, largely unburnt. On any quality scanner or Modis you will see that the injector pulse is wider than usual when the engine is under load, the greater the load the wider the pulse as well as timing adjustments, because it is compensating for the "KNOCK", there for is using more fuel!

YOU can argue what you want to and I will argue what I know and have experience with. To each their own, you teach your flock and I will share my knowledge with whom ever wishes to know.

By the way the Toyota will not register any thing on the gas analyzer! I do have a friend that runs an emission station for the state. The Cavalier was returned to normal and exchanged hands.

You are so blind to your position. I agree with your assessment that there are great variables out in the real world. I have said repeatedly, "with all else being equal". With equal energy content, with equal fuel density, with equal additives, . . . fuel octane being the only variable . . . engines will produce the same power and efficiency. You keep referring to your "real world experience" which is OK if you just simply said "my real world experience shows me that there is variability in the fuel and the resultant performance". But then you go on and attack the lab work that shows that "with all else being equal" fuel octane does not dictate the spark ignited ICE's power and efficiency.

I work in industry as a R&D professional. When I write up a grant proposal, it goes under severe scrutiny. When I publish a white paper, it goes out for peer review of other professionals. And even when I stand in front of the company I now work for and partially own, I must be clear and convincing to the board in suggesting the direction of work and investment in funds or they will tell me to start over and come back later . . . and it rarely is said that nicely.

Don't take critical arguments so personally. Find the salient points and argue with clarity and lucidity to those points.

And I am interested in your Toyota and it's low emissions. I have run across several vehicles, two of which I have owned, that seem to run unusually cleaner then most and barely register on the test machines here in our area. I believe you are in Georgia, correct? I live in San Diego county and my business is located in the LA basin under the CARB and AQMD restrictions. Georgia has to meet Federal 49 state requirements and your testing will reflect that. California has it's own more strict requirements and my vehicles registered here in San Diego county must meet those Federal as well as the Cal state requirements. However, the poor air quality in the LA basin means our testing is among the most strict and sensitive in the world! I cannot test my work vehicles in San Diego because their testing machines and procedures do not meet the AQMD and CARB rulings. I will dig up the old test reports for my Diahatsu. I would like to compare them to your Toyota. Assuming you have the printouts.

[Madsceintist]

"So you wish to say that the octane rating has absolutely nothing to with power or performance, CORRECT?"

I wasn't agreeing with you here................
What I was saying is that it does, and explained why !

We tested on the Toyota but to by-pass the states system it wasn't finalized, so no printout. If he finalizes it then the state charges a fee to the station and it automatically gives you one free retest. However its not about the states emission testing or not, which due to zero detectable emissions it wouldn't pass anyhow. My associates with the dyno are getting a little high for just experimenting, I do have a man that I worked for 11 years ago that has a sun gas analyzer, so I may be able to entice him to plug it in .? My visual inspection is actually a pass, and the gas cap is a dummy. I have plastic covers to hide a few small items under the hood and they don't check under the car for anything but a convertor which is hollow. We don't have the old visual inspection for safety, only the emissions, for registration. I wanted the states visual and mechanical inspection so as to deem the car alternative fuels excepted, this by-passes any further inspections on this car.

Out side of work and home I don't get the kind of time I wish to spend on this anymore. Instead of being on here I should be in the shop!

[RustyLugNut]

Keep up your experiments.

[myoldyourgold]

Madsceintist, RustyLugNut, I really believe you guys are saying the same thing and this it is just semantics.

Not that Wikipedia is the best source but it doses save time.

Many high-performance engines are designed to operate with a high maximum compression, and thus demand fuels of higher octane. A common misconception is that power output or fuel efficiency can be improved by burning fuel of higher octane than that specified by the engine manufacturer. The power output of an engine depends in part on the energy density of the fuel being burnt. Fuels of different octane ratings may have similar densities, but because switching to a higher octane fuel does not add more hydrocarbon content or oxygen, the engine cannot develop more power.

However, burning fuel with a lower octane rating than that for which the engine is designed often results in a reduction of power output and efficiency. Many modern engines are equipped with a knock sensor (a small piezoelectric microphone), which sends a signal to the engine control unit, which in turn retards the ignition timing when detonation is detected. Retarding the ignition timing reduces the tendency of the fuel-air mixture to detonate, but also reduces power output and fuel efficiency. Because of this, under conditions of high load and high temperature, a given engine may have a more consistent power output with a higher octane fuel, as such fuels are less prone to detonation. Some modern high performance engines are actually optimized for higher than pump premium (93 AKI in the US). The 2001 - 2007 BMW M3 with the S54 engine is one such car. Car and Driver magazine tested a car using a dynamometer, and found that the power output increased as the AKI was increased up to approximately 96 AKI.

[RustyLugNut]

Madsceintist, RustyLugNut, I really believe you guys are saying the same thing and this it is just semantics.

Not that Wikipedia is the best source but it doses save time.

It is not a matter of semantics. It is clarity of thought. "All else being equal" seems to be beyond many people's grasp. If you isolate the effects of octane on power and efficiency, you will see that there is no correlation! This is not my PERSONAL belief, but industry accepted FACT!

I know about detonation and power degradation. That is NOT the focus point of my argument.

Look at the two paragraphs you just linked to . . . they support my position.

[myoldyourgold]

I know about detonation and power degradation. That is NOT the focus point of my argument.

Look at the two paragraphs you just linked to . . . they support my position.

This is where we will agree to disagree. It supports both positions. That is why I said what I did and posted what I did. You have to compare apples to apples. Higher octane does yield better results in high compression engines even if the actual energy/density in the fuel is the same. The reverse low octane is also true in the same engine resulting is poor results. The difference is the compression which makes the fuel react differently. I think this horse has been beaten enough.

[RustyLugNut]

This is where we will agree to disagree. It supports both positions. That is why I said what I did and posted what I did. You have to compare apples to apples. Higher octane does yield better results in high compression engines even if the actual energy/density in the fuel is the same. The reverse low octane is also true in the same engine resulting is poor results. The difference is the compression which makes the fuel react differently. I think this horse has been beaten enough.

A quote from the pro tuners at factorypro.com, an AMA site:

Does using a fuel with higher octane numbers automatically make more power?
Not unless they are preventing "knock".

Also from factorypro.com:

How much lead was in "leaded" fuel?
By law, fuels intended for on road use have been limited in maximum lead content for some time. Maximum lead content was limited to .15 to .33 grams/Liter in the late 1970's.
Lead poisoning causes brain damage. Most fuel has been unleaded for quite some time. People born after the late 70's must be much smarter than the older people.

Since I am from the Kennedy administration, I must be stupid in comparison to the young whipper snappers around these parts.

[myoldyourgold]

A quote from the pro tuners at factorypro.com, an AMA site:

Does using a fuel with higher octane numbers automatically make more power?
Not unless they are preventing "knock".

Also from factorypro.com:

How much lead was in "leaded" fuel?
By law, fuels intended for on road use have been limited in maximum lead content for some time. Maximum lead content was limited to .15 to .33 grams/Liter in the late 1970's.
Lead poisoning causes brain damage. Most fuel has been unleaded for quite some time. People born after the late 70's must be much smarter than the older people.

Since I am from the Kennedy administration, I must be stupid in comparison to the young whipper snappers around these parts.

Again the same thing. High compression engines would have a Knock problem if high octane was not used thus producing more or less HP depending on the octane. The same engine with low octane produce less HP because of the knock problem. It is not the fuel energy because they are the same. It works both ways in the same engine. My 350 ZZ4 engine making 485 HP and has a difficult time running on 93 octane without some octane boost. Now lower grades I am lucky to make half that HP but can drive it under the knock if I had to.

I do not know who you are calling young whipper snapper because I have been retired for 15 years. Had a lot of water go under this bridge. That is a complement for me anyway. LOL I know of no one who thinks you are stupid but just the opposite.

[RustyLugNut]

Again the same thing. High compression engines would have a Knock problem if high octane was not used thus producing more or less HP depending on the octane. The same engine with low octane produce less HP because of the knock problem. It is not the fuel energy because they are the same. It works both ways in the same engine. My 350 ZZ4 engine making 485 HP and has a difficult time running on 93 octane without some octane boost. Now lower grades I am lucky to make half that HP but can drive it under the knock if I had to.

I do not know who you are calling young whipper snapper because I have been retired for 15 years. Had a lot of water go under this bridge. That is a complement for me anyway. LOL I know of no one who thinks you are stupid but just the opposite.

No, it is not the same thing. He was challenging my assertion that if I put 93 octane in my Diahatsu, it will still only get 50 mpg and produce 51 HP, "all else being equal". Using real world data which is correct in and of itself to explain away lab results is off base. His conclusions about his experiences are spot on. His application to my lab work was incorrect. As much as science and art have rules, there are rules to productive argument. Define the salient points. Attack and defend. Come to a conclusion, then move on. He could not grasp the salient points. My failure was to continue the argument even realizing this.

And no, I was referring to all the younger people who argue that I am too old to understand new things. So, I just gave them the supposition that it might be due to our generation absorbing gasoline fumes and eating paint chips.

[myoldyourgold]

OK I still understand both sides of this argument. Not knowing the exact condition of your engine or its compression I can see where both could still be right if your engine has enough compression to knock causing the computer to correct it so you do not sense it. If it does then with higher octane then the computer would not sense the knock and not retard the timing and more HP could possibly be made. This very well might not be the case in your engine but a possibility. You I could assume are correct in regards to your own engine knowing or having used high octane and not found any difference. On the other hand the opposite is perfectly logical and is possible. I like it when I can say both are right. LOL Lets move on because I think this has strayed far enough to not be of much value to anyone. Even though I have had some disagreements with Madsceintist I still respect his depth of knowledge and experience when it comes to the automobile. It requires much more than just an efficient reactor to make this all worth while. That is just the beginning. The actual use of HHO to have a gain is much more involved especially with the new engines. They are pretty efficient to begin with but still have gains to be had in most of them. Now back to work