93 Octane! I like it!

[Punkindave]

A few years ago, my oldest daughter had an internship at Duke University and it meant about a 50 minute (avg) commute 1 way - now it included rural roads, city and freeway driving. The car was a Mazda 3, with a 2.5 and automatic. We measured the mpg from 2 gas stations - filled up on Saturday each time and the difference was 2 or more mpg difference. We did the same test twice to be sure.The winner was a few cents higher per gallon but they stated it was Top Tier Gasoline. I've been using name brand gas in everything ever since. Oh - and it was the regular 87 each time.

I normally run the local convenience store 87 octane fuel (Wawa, Sheetz, etc)
One day I was running VERY low and stopped at a Shell station and tanked up. The fuel mileage gage was immediately showing substantial differences and the next fill up calculated a 2mpg difference!! I've since filled at Exxon/Mobil and other Shell stations and seen the same results. No butt dyno improvements, but the savings is indisputable. I drive 120mi/day so any savings is good!
Now to try the next tank at the local Wawa to see if it goes down again.

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[word302]

I normally run the local convenience store 87 octane fuel (Wawa, Sheetz, etc)
One day I was running VERY low and stopped at a Shell station and tanked up. The fuel mileage gage was immediately showing substantial differences and the next fill up calculated a 2mpg difference!! I've since filled at Exxon/Mobil and other Shell stations and seen the same results. No butt dyno improvements, but the savings is indisputable. I drive 120mi/day so any savings is good!
Now to try the next tank at the local Wawa to see if it goes down again.

This is what most people don't understand. If you're 3.6 isn't performing optimally on 87 you're probably buying junk gas.

 

[Rogues Gambit]

It's like anything else, every once in a while, you get yourself, your family, your car, etc. A treat

 

[word302]

It's like anything else, every once in a while, you get yourself, your family, your car, etc. A treat

Engineers and science would argue that this particular treat does absolutely nothing.

 

[Rogues Gambit]

Engineers and science would argue that this particular treat does absolutely nothing.

Well, Dr's and dietitians would argue that you shouldn't have dessert and alcohol either, but it's not like you'd have it all the time now

 

[srt20]

LMAO fantastic thread!!!

 

[roaniecowpony]

I'll probably use 91-93 if I tow a travel trailer.

 

[Joker4L]

Here in Georgia the difference between 87 and 93 Octanes is about .70cents. At about 16 gallons a fill up, any tiny improvement isn't worth the extra $11 a fill up. I fill up 5 to 6 times a month so thats an extra 60 plus dollars a month. Sorry I will run 87 all day, I will at least due Top Tier Fuel lol

 

[Headbarcode]

My turbo JLUR only ever drinks mobil 93. No clue what the price difference is compared to regular, but whatever it is, is a small price to pay for the peace of mind in knowing that I'm doing my part to keep it happy and running at its best.

I was under the impression that the v6 isn't a high enough compression engine to require more than 87? I've been reading about some that are using higher octane to battle against pinging/fuel knock, but that might be a mask for an underlying issue.

 

[Crusifix]

The ECU in these jeeps will run spark up against the knock threshold. Once the sensors detect knock it will pull the timing down. A higher octane will increase this threshold and allow about 3-4 extra degrees of timing on 93 octane before knock is detected and spark timing is set.

 

[Martindfletcher]

I heard I think litebrite the compression ratio is like 11:1. Higher octane should smooth it a bit. Doubt its enough to mpg to offset cost. Certainly in some environments it runs smoother.

 

[Martindfletcher]

The compression ratio is 10.2:1 in the 3.6 included in the JL. You may be thinking of their video where they turbod their 3.6 and that was an entirely different thing.

Why would the turbo increase a compression ratio? Isn’t just dependent on stroke, cylinder head volume and piston diameter ?

 

[Martindfletcher]

https://www.allensoffroad.com/community/thread-36-post-74.html

 

[higbyz]

My turbo JLUR only ever drinks mobil 93. No clue what the price difference is compared to regular, but whatever it is, is a small price to pay for the peace of mind in knowing that I'm doing my part to keep it happy and running at its best.

I was under the impression that the v6 isn't a high enough compression engine to require more than 87? I've been reading about some that are using higher octane to battle against pinging/fuel knock, but that might be a mask for an underlying issue.

I run 91 octane non ethanol in everything. Pretty sure if the engines could talk , they would thank me.

 

[jdubya421]

Why would the turbo increase a compression ratio? Isn’t just dependent on stroke, cylinder head volume and piston diameter ?

I meant an entirely different issue altogether, but I guess I was wrong about the ratio.

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