exactly, its all about the timing. The JK engine is not tuned for 93 octane. It won't hurt it but it won't help either. Now im not sure about any of the programming available for these engines but if they allow you to adjust your timing retard then you can tune the engine for 93 or even 100 octane if you so choose. A lot of the new engines will adapt to lower octane but unless the engine was designed for higher octane it will have no way of knowing its running the higher octane. So no benifit. Timing tho should have very little effect on fuel economy. The only benifit to having the engine tuned to 93 octane would be more power.

The designation of gas as regular, plus, and premium is a clever trick by the gas companies for people who know nothing about octane. Oh so the premium must be best for my car. What gets me is that people who do this will argue with you to the death but they have nothing to base thier opinion on except that "I can tell it runs better".

 

dynos are not very accurate tho, we need some kind of engine diagnostics program so we can see if the timing adapts.

 

I would be interested in knowing the technical background of anyone posting to this thread. Gas is not black magic it is based on known scientific principles.

 

3 years of slammin Soju & various mixes of Jungle Juice.

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as for the other part:

Well, i tried the High altitude, low octane Denver Colorado 3.2 beer,
And the Higher Octane Molson's Brador Beer.

According to the dyno the cops stuck in my mouth, i fared far better on the lower octane stuff.

The Canadian octane stuff, in my perception got my motor running better, but i was in fact curled up by the throne and dreaming the whole thing.

What was the question?

 

internet junkie, car forum addict, my friend does aftermarket programming on volkswagens and audi <--- where I got most of my information. I also work with a lot of mechanics and get to chat with them quite often. There are plenty of articles about octane on the interent tho. Wikipedia octane and see what comes up. You don't have to trust us. :toung:

 

87 in the JK... i regularly get 20mpg.

I run 89! (midgrade) not premium, KID. In my low compression 1968 GM 327 V8 from a Vette. And it barely needs it, PREMIUM or 93 octane makes it run horrible.

SO, your tellin me that this 3.8L v6 runs better off of higher octane fuel when my V8 doesn't even need it...

You still haven't learned yet have you?

 

He obviously doesn't have a clue about anything, and I think he's just trying to fire everyone up. It obviously worked.

Don't feed the trolls!

 

It's unfortunate that you don't wish to share the details of your testing. For those who are interested, while my background is in engineering avionics systems, and not fuels, I do have quite a few years in developing and running test regimens. The result you cite (reduced HP with higher octane fuel) could be due to any number of factors. Let me ask a few rhetorical questions, not because I'm trying to goad you into answering them, but to demonstrate to the readers of this forum that testing octane, scientifically, is not as easy as your quote suggests. Specifically:

1. What actions were taken to isolate the change in octane as the only change in the test configuration? IOW, were temperature, humidity, engine condition, etc. all controlled to ensure that they were identical during each pass of the test? A simple example of where a problem could occur: Run the test the first time with a cold engine using one fuel, then with a warm engine and the other fuel.

2. How many pass-throughs were made for the test? When there is no specific reason to determine a number, three is a generally accepted minimum number. Therefore, was each test repeated at least three times, and were idendital results obtained each time?

3. How were the fuels certified as to octane rating? Ideally, an independent lab would have tested and certified each fuel. If the rating was determined by layman simply buying fuel from two different pumps, then the results are suspect.

4. What specific controls were in place to ensure the accuracy and precision of the test measurement apparatus, including the elimination of environment factors impacting test measurements?

This is just a sampling of some of the issues that a proper, scientific testing regimen would consider. And, bottom line is, it won't provide real world results! That's because during real world operation, factors that are held constant in the laboratory test are in fact changing.

So, I'm not going to argue with someone who says he has measured his gas mileage and gets better with this octane or that. It's his dime (per gallon). I don't seriously accept that he's doing harm to the engine unless the octane is so low that he has serious knocking. And, at that, I believe that the JKs engine will adjust itself on the fly (again, I'd be interested in a technical description from someone knowledgeable of what's going in in the engine as the octane level of the fuel changes).

 

Reading this thread reminds me of Carl from Sling Blade....while everyone stood around the lawnmower and tried to figure out why it quit running....Carl (with a single digit IQ) pointed out that it was out of gas!!!

You don't need a 14 page scientific regimen to figure out sh*t stinks!

If running a higher octane than 87 would net 2-3 more mpg, don't you think in this world of corporate average fuel economy (CAFE) that Jeep would tell you to fill with the higher octane and boost their fleet ratings?

There is enough research out there to tell you that burning higher octane than recommended is not going to net 2-3 more mpg. Believe what you want to believe.

 

I believe this is just another H2/3 Verses Jeep thread, just rebadged.

Everyone has their own opinion and/or set of facts to support their own side.

• You think 93 works best, great!
• You think someone spent to much on 93 and it doesnt work? Awesome!

i do not believe either side will be baptising any converts today.

All i know is it is MONDAY :sad: ... and i would rather be out doing field research on gas milage than be at work on my break. I believe...

...i need a beer.