Sirikool

^^^FINALLY! someone who actually thinks. I couldn't say it better myself. thx vin.

os_carlover

ya what bigvinnie said

BigVinnie

iTrader: (2)

Whats funny is that if I mentioned anything like this in Zilvia I would of had nothing but rebudles and contradictions (some people think that they could of said it better), just for not using a correct term or something........
Thanks guys, I'm also learning patients and to be polite instead of going off on someone and calling them stupid, (that gets people No where).............

Preston

Vinnie's the man, Unless you directly attacked somebody for no reason I don't think I'd ever get into a fight with you. I've learned so much off you in the year I've been on these forums. It's awesome to have an in-house tech genius. Keep up the good work.

Just thought it was time to thank you for your hard work.

PNG

Actually, Vinnie's wrong in this particular case. Octane has nothing to do with oxygenation. It's strictly a measure of a fuel's resistance to pre-ignition, and bears no relation to energy content, O2, or anything else. As a matter of fact, many states (California included) mandate oxygenate formulas during the winter months for all grades of gasoline.

BigVinnie

iTrader: (2)

Actually PNG you are going to need proof to back it up.....
Here is from Perfect Power article on knock sensor installs. It specifically states the use of the knock sensor and it's effects on timing.

QUOTE Perfect Power:

Knocking is caused by the burning of the gas inside the cylinder BEFORE the piston goes down. Some people call it detonation. In any case, the piston gets a big knock, which may eventually destroy it. This is bad news ! Bad fuel, or advanced timing, or high temperatures cause knocking.

Some cars employ knock sensors to retard the timing if knocking is detected. It then advances the timing again until it detects knocking, thus adjusting the timing to the optimum point all the time. Fantastic! I like it!

If you want to retrofit an engine with a knock sensor, you are faced with extreme difficulties. Normal engine noise is un-distinguishable from knocking above 4000 RPM. Even by ear.

Where do you place the knock sensor? This is a major problem, because the sound of one cylinder knocking travels a different path as other cylinders and may eventually cancel itself and you detect nothing. Some manufacturer has 5 different locations for knock sensing.

http://www.perfectpower.com/technical_info/knock.asp

Quote from gas facts:
Simply put, the octane rating of the fuel reflects the ability of the
unburnt end gases to resist spontaneous autoignition under the engine test
conditions used. If autoignition occurs, it results in an extremely rapid
pressure rise, as both the desired spark-initiated flame front, and the
undesired autoignited end gas flames are expanding. The combined pressure
peak arrives slightly ahead of the normal operating pressure peak, leading
to a loss of power and eventual overheating. The end gas pressure waves are
superimposed on the main pressure wave, leading to a sawtooth pattern of
pressure oscillations that create the "knocking" sound.
http://www.faqs.org/faqs/autos/gasoline-faq/part3/


Here is how to fool your O2 sensor to increase gas mileage....
I added this for the Fudge of it........
http://pesn.com/2005/03/17/6900069_Acetone/

If an O2 sensor, and knock sensor wasn't valid in todays automobiles then 12.1:1 compression engines and higher would have a very hard time running on 91 octane.....


True octane is denser in content (as described in the stoichiometric air/fuel giving it a higher resistance to burning, although hydrocarbons are the main product of fuel go unchanged (it burns the same). If you look at the stochiometric it explains pretty well that there is residual O2 after combustion, denser Octane, not hydrocarbons release more residual O2.........

If ecu tunes weren't proof enough to show gains of upto 6% utilizing higher grade fuels, to impending knock sensor responces to increase timing, and O2 signals to increase fuel dumping, then nothing that I just said would of been valid.....
But then again PNG I'm assuming that you are oldshool in your methods, using a SOHC with without a KNOCK sensor. Explains why using lower grade fuels may be easier to use and achieve for you especially since the SOHC's run on a lower compression anyway......

PNG

I'm not debating the role of the knock sensor. I'm not even sure where you got that from, considering what I said in my original post.

I'm merely pointing out that fuels with higher octane ratings aren't always oxygenated, and that oxygen content has nothing to do with octane rating.

Try not to confuse the issue by going off on a mileage tangent. Also, the paper you cite on stoichiometric burning seems mostly concerned with natural gas burning under atmospheric pressure (as in furnaces), and has nothing to do with internal combustion engines or anti-knock properties. As a matter of fact, the word "octane" appears only once in the paper, as part of a table of selected hydrocarbons and their corresponding air requirements.

Not looking to pick a fight or anything here, but the fact that you're citing completely irrelevant sources isn't giving me a lot of confidence in your premise.

Am I missing something here? You ARE saying that high-octane fuel is oxygenated, and the reason that it better resists knock is because it's fooling the ECU into running richer, right? If so, then wouldn't high-octane fuel be useless in an engine without an O2 or knock sensor, such as, say, a high-compression carbureted V8?

BigVinnie

iTrader: (2)

The stoichiometric chart was just used to show properties and composition. You are right it is mostly used for the measurement of natural gasses (well that chart at least), not gasses used in the combustion chamber. It did show that Octane is infact the denser of all the fuels.... Thats all..... Higher ratings and obviously harder to burn...... The stoichiometric still follows the same principles and properties when used with octane unleaded fuels.It also showed it's chemical composition. I think that maybe I just didn't explain myself well in the begining, but defenitely wasn't wrong.....
You were arguing that higher grade octanes don't at all effect the use of the O2 sensor. When infact even in vaporization O2 is one of the main elements left behind in the byproduct of Octane.
Shure maybe 20years ago octane fuels did play a larger roll in knock in ping and in the compression of the engines make up. Rather than it does in todays vehicles which atomize fuel to air much better, with higher compressions on lower octanes ( more due to technological advancements in engine management). This means that the grade fuel that is used controls more of the engines timing characteristics to it's compression, rather than just strictly using a fuel to prevent knock and ping from having high compression.
Engines are much more regulated by engine management more than the fuel that is used. The type of fuel and the way it is used today isn't at all in the same manner or characteristics that we used it as over 20 years ago.
My main arguement was that it isn't fuel in general that is harder to burn but more of it's make up in octane, the majority of fuel is hydro carbons.......
My arguement was that if you also use lower grade octanes such as the 87~89 octane it would decrease fuel economy which was one of my main arguements and still hasn't been proven other wise by you. Besides using lower grade fuels gums up injctors and does more damage than good IMO.
My other arguement is that it isn't fuel that is harder to burn, but rather the octane which makes up only one part of the composition of fuel when added to hydrocarbons, which in the combustion chamber the chemical composition is split in order to cause detonation anyways.
Everything I mentioned in this thread is right here and says that I am 99.9% right!!!!!!
This will probably help explain the requirements of octane fuel, to compression.
http://www.faqs.org/faqs/autos/gasol...section-1.html

PNG

I'm still not with you here, because "octane" as defined in "octane rating" doesn't have anything to do with the chemical makeup of a fuel - it's a reference to the fuel's knock resistance as compared to pure isooctane, which is given the arbitrary value of "100" on the scale, and n-heptane is "zero". A 50-50 mix of isooctane and n-heptane would have a rating of "50", and so forth.

Fuels that contain no actual "octane" (the chemical) still have an "octane rating." For instance, pure methanol rates higher than 140 on the "octane" scale, yet has no actual "octane" in it.

Referring back to the PDF, I again point out that the only place the word "octane" appears is in the table of stoichiometric ratios. I'm not sure where you're getting the idea that this document somehow supports the idea of hidden oxygen in octane.

You claim that octane (the chemical) "does infact use O2 as an element in it's composition." This is simply not true. In actuality, the chemical formula for octane is CH3(CH2)6CH3. You will note the lack of the letter "O" anywhere in that formula.

If fuel with an 87 octane rating is sufficient to allow an engine to run optimum ignition timing, then 89 or 91 will have absolutely no benefit for performance or fuel economy. If the ECU uses a knock sensor and is pulling out timing, then yes, the engine won't run as well. But "high enough" octane rating is just that - once the fuel has enough detonation resistance to allow the engine to run with its designed ignition timing and air/fuel ratio, additional detonation resistance doesn't do anything. As for "gumming up the injectors," octane rating has absolutely nothing to do with the situation either. That's a function of the additive package blended in by the refinery, not the detonation resistance of the fuel. Because 87 octane gas is sold on price, not performance, it may not get the same additive package as the same company's Premium (which costs another cent or so per gallon to make with the additional chemicals), but all gasoline has to meet a minimum requirement for detergency set by the federal government.

CowboyTurbo

wow~ I'm learning so much. I feel so smart now.

BigVinnie

iTrader: (2)

O.K PNG hands down you have me on the Octane debate after looking it up in the wikipedia. I did infact look at the chemical composition.
First off there is no Oxygen found in octane, nore in the biproduct of octane. (thanks for the correction humility is bliss, I am laughing at this mistake of mine). O2 is infact found as remenants left behind and not used in the combustion process. level of O2 will vary from level of octane used, timing, and fuel dumping...
Octane comes from the chemical composition of Alkanes. (ALKANES) are nothing more but Saturated Hydro Carbons.

http://en.wikipedia.org/wiki/Gasoline#Energy_content


There is infact oxygen used in the distilling process of fuel, and it is mandatory to use 2% oxygen determined by the weight of the fuel.

PNG

I'm glad we got that sorted out, and I have nothing but admiration for the way you handled the whole thing. I hope I'm as gracious when I inevitably find myself in the same situation.

BigVinnie

iTrader: (2)

It's all good man...
I thought I should clarify Octane ratings on the KA's though. I only mentioned the rating for the DOHC's...
DOHC's perform the best on premium fuel (cali's supreme of 91 octane). As proven since they use a knock sensor the engine will decrease performance and gas mileage using any other lower octane's.
Since you have the SOHC PNG I wanted to clarify the Octane rating for the SOHC. People have told me for performance and best gas mileage to use 89 Octane on the SOHC's since they run a lower compression than the DOHC's....... What does the factory manual say, and what is your opinion...........

PNG

I'll have to see if I can dig up my owner's manual. Personally, I run it all the time on 87 and have yet to hear any detonation or see signs of it on the plugs. I've even dynoed on the bottle with a tank full of 87 and full, stock timing and haven't seen it - that's how low the CR is. I run 91 when I go to the track, just for safety, and my nitrous jetting is what I would consider "safe rich." Based on where the "temper line" is on the plugs' ground strap, I'm going to start taking 2 degrees out at the track, but that's about it.

BigVinnie

iTrader: (2)

Why not just add some boosters or methanol to the fuel mixture?
Although I think octane boosters are a scam and cost too much, would work if you added a couple bottles, at a rip off price......