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3.6 - For Those Running Premium Fuel

Kreepin1

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You have absolutely no place from which to call me ignorant or my opinions unfounded. You haven't even read what I posted. Go back and read or shut your mouth.
Yes he does. In this thread you have shown you do not know the basics of internal combustion engines. You said "the internals of a 3.6l pushrod V6? Old as dirt" and when it was pointed out the 3.6 is an OHC architecture you said "OHC is even older."

Several people have tried to educate you about the relationship between compression ratios, ignition timing, and engine performance. The danger of knock and excessive EGT's has been explained. Yet your position that "the manual says there is no benefit to anything over 87 octane" remains unchanged.

We've read the nonsense you've posted. You've been weighed. You've been measured. You've been found wanting. It is you that needs to go back and read or shut your mouth.
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TheRaven

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In this thread you have shown you do not know the basics of internal combustion engines. You said "the internals of a 3.6l pushrod V6? Old as dirt" and when it was pointed out the 3.6 is an OHC architecture you said "OHC is even older."
BS...you're really reaching. There's nothing incorrect in what I said. Pushrod automobile motors are old as dirt and OHC is even older. That's absolutely true, and nowhere did I say I was referring to the Wrangler 3.6l...it was a broad general example.

Several people have tried to educate you about the relationship between compression ratios, ignition timing, and engine performance. The danger of knock and excessive EGT's has been explained. Yet your position that "the manual says there is no benefit to anything over 87 octane" remains unchanged.
It's not "education" when i'm already thoroughly familiar with these principles. Again, IF YOU ACTUALLY READ WHAT I SAID, you'd realize that i never disputed any of those things. What you are neglecting to understand is that all these technical details are irrelevant if the end result is no net difference - and that's what FCA is also trying to tell you. Premium fuel does make a difference, just not one that matters to the end user. You aren't going to gain appreciable efficiency, power, or longevity.

So no, you haven't read, or measured, and you are in absolutely no position to judge. You are all just trying to support and elevate what you believe into manufactured truth because you want to feel superior.

Again, you want to run premium for whatever reason you want to run premium? Fine. Maybe it really does give YOU some benefit. I can't tell you you're wrong about that. Just don't go around spreading this farce and freaking people out over nothing. Like I said, this exact same farce exists on every car forum ever and it's the same BS over and over again...yet here you are STILL perpetuating it.
 
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Kreepin1

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BS...you're really reaching. There's nothing incorrect in what I said. Pushrod automobile motors are old as dirt and OHC is even older. That's absolutely true, and nowhere did I say I was referring to the Wrangler 3.6l...it was a broad general example.
More nonsense... The words in quotes are copy/pasted from your post. You said "the internals of a 3.6l pushrod V6" and I am aware of no such animal. Why would you mention a pushrod engine at all in this thread unless you truly didn't know?

As to engine architectures it is generally accepted that for production vehicles we had flatheads, then OHV (pushrod), then OHC. Wikipedia tells us flatheads were used from the 1890s until the mid-1950s. The first production OHV engine was released by Buick in 1904. The first production OHC engine was released by Isotta in 1910. But OHC engines were restricted to exotics (Crosley, Duesenberg, Sunbeams and such) until the 1980's. There are exceptions like Pontiac's straight 6 built from 1964-1969. You can weasel as much as you want, but you were wrong. OHV came before OHC.

It's not "education" when i'm already thoroughly familiar with these principles. Again, IF YOU ACTUALLY READ WHAT I SAID, you'd realize that i never disputed any of those things. What you are neglecting to understand is that all these technical details are irrelevant if the end result is no net difference - and that's what FCA is also trying to tell you. Premium fuel does make a difference, just not one that matters to the end user. You aren't going to gain appreciable efficiency, power, or longevity.
There is some truth to what you say. Someone that keeps their vehicle stock, drives on relatively flat terrain and only pushes the engine hard on the occasional on-ramp is most likely fine with regular fuel in the Wrangler with 3.6. In contrast someone with big tires, lots of add-on's and long hills to contend with is going to benefit from premium.

But you have taken the first case and applied it broad brush to the second group. Pay attention. The engine and tune are optimized (among other things) for the EPA's fuel economy test loop. That test uses ethanol free free fuel roughly equivalent to PREMIUM. With lower octane fuel the ignition timing is retarded under high load conditions. This reduces power and also triggers excess fuel to dump to keep the catalytic convertor from overheating. Which if it fails gets sucked past the exhaust valves and ruins your engine. So for people in the second group, or people that notice their engine runs rough on regular, premium is a good idea. Get it? Or are you so stubborn that you'll keep claiming OHC came before OHV?

Again, you want to run premium for whatever reason you want to run premium? Fine. Maybe it really does give YOU some benefit. I can't tell you you're wrong about that. Just don't go around spreading this farce and freaking people out over nothing. Like I said, this exact same farce exists on every car forum ever and it's the same BS over and over again...yet here you are STILL perpetuating it.
As far as I'm concerned, you are the only person freaking out.

Me? I did what I said I would earlier in this thread. I'm running a Livernois tune and have been exclusively on 105 octane E85 for the past year. My Jeep drove nice before, and is AMAZING now.
 

quick66

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Caveat...I didn't read all 20 pages. Generally speaking I think you want the lowest octane fuel that will burn without detonation. Lower octane fuel will have a faster burn, and perhaps a better flame travel, resulting in a more efficient combustion. There are many things that factor into this such as piston design (dome vs. dish), combustion chamber size, valve shrouding, quench, etc...

I've heard some people say higher octane fuels may burn cleaner, but maybe that has more to do with the additive packages than the higher octane? I don't honestly know how or if carbon buildup is effected by burn rate differences.

I spent a lot of years drag racing and messing with different fuel types. Even in newer rigs you can get surprising results with different fuels. I had a Ford F150 Screw cab with the 3.5 eco boost. Aftermarket intercooler and tune otherwise stock. It really liked the VP highly oxygenated fuel and would gain 2+ mph through the 1/4 mile over regular pump 93 premium. I used a weather station and kept meticulous notes to ensure true A-B-A testing. So I had a pretty high degree of confidence that the improvement was entirely fuel related. Fuel/octane discussions are always interesting and divisive, lol.
 

1BadManVan

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Caveat...I didn't read all 20 pages. Generally speaking I think you want the lowest octane fuel that will burn without detonation. Lower octane fuel will have a faster burn, and perhaps a better flame travel, resulting in a more efficient combustion. There are many things that factor into this such as piston design (dome vs. dish), combustion chamber size, valve shrouding, quench, etc...

I've heard some people say higher octane fuels may burn cleaner, but maybe that has more to do with the additive packages than the higher octane? I don't honestly know how or if carbon buildup is effected by burn rate differences.

I spent a lot of years drag racing and messing with different fuel types. Even in newer rigs you can get surprising results with different fuels. I had a Ford F150 Screw cab with the 3.5 eco boost. Aftermarket intercooler and tune otherwise stock. It really liked the VP highly oxygenated fuel and would gain 2+ mph through the 1/4 mile over regular pump 93 premium. I used a weather station and kept meticulous notes to ensure true A-B-A testing. So I had a pretty high degree of confidence that the improvement was entirely fuel related. Fuel/octane discussions are always interesting and divisive, lol.
basically, buried in this thread, there is a tuner in here that showed lots of data and examples specific to these motors running on 87 vs 91 and showed the benefits to the motor while even on the stock tune when it comes to knocking. showed the data logs and all. And one guy here has a major hard on for the owners manual and refuses to believe any data being shown to him about it lol. Again, to each their own on what they want to run in their jeeps.
 

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On the highway, I get between 23MPG and 29MPG in my 3.6L eTorque 8 speed Unlimited Sport S going the speed limit with cruise on. In town, though, I think I hit 20MPG if I am lucky.
I recently bought a "22 Willys 2 dr 3.6l and auto. On a 2 hour round trip drive, taking it easy and doing the speed limit I got 8.8l per 100km which is approx 26mpg. Incredible for this Jeep. Oh, and I have 275/70/17 Firestone XT tires

PS running 87 octane(regular)
 

TheRaven

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More nonsense... The words in quotes are copy/pasted from your post. You said "the internals of a 3.6l pushrod V6" and I am aware of no such animal. Why would you mention a pushrod engine at all in this thread unless you truly didn't know?
You aren't aware of pushrod 3.6l V6s?! And i'm the one who "doesn't know"? Read up.

https://www.google.com/search?q=3.6l+pushrod+motors

As to engine architectures it is generally accepted that for production vehicles we had flatheads, then OHV (pushrod), then OHC. Wikipedia tells us flatheads were used from the 1890s until the mid-1950s. The first production OHV engine was released by Buick in 1904. The first production OHC engine was released by Isotta in 1910. But OHC engines were restricted to exotics (Crosley, Duesenberg, Sunbeams and such) until the 1980's. There are exceptions like Pontiac's straight 6 built from 1964-1969. You can weasel as much as you want, but you were wrong. OHV came before OHC.
LOL "It is generally accepted". I love these plays. The attempt to make it seem like what you believe is common knowledge. I dunno, maybe it works sometimes.

Anyway, the first automobile application for OHV was Buick in 1904. OHC was Maudslay in 1902.

https://en.wikipedia.org/wiki/Overhead_valve_engine

https://en.wikipedia.org/wiki/Overhead_camshaft_engine

There is some truth to what you say. Someone that keeps their vehicle stock, drives on relatively flat terrain and only pushes the engine hard on the occasional on-ramp is most likely fine with regular fuel in the Wrangler with 3.6. In contrast someone with big tires, lots of add-on's and long hills to contend with is going to benefit from premium.
OH wow look at this, FINALLY an attempt at a real discussion. Ok, lets do it.

You say "benefit from premium". I guess that's our issue because our definitions of "benefit" are probably very different. You could say "they will benefit with less knock and better spark advance"...but to me, that's not a benefit. Until I get more power, better efficiency, or some positive effect on longevity...I see no benefit. I'm putting more in (money), I should be getting more out. Perhaps you can convince me of some benefit I haven't thought of outside of those categories?

So for people in the second group, or people that notice their engine runs rough on regular, premium is a good idea.
SMH...for a second I thought you had actually read. Clearly you didn't. I have never said that someone who feels that their engine runs better on premium shouldn't run premium. See, this is the problem. Words have been put in my mouth and opinions have been assigned to me that aren't mine.

As far as I'm concerned, you are the only person freaking out.
You have the wrong impression. Freaking out is not my disposition. SMH is a much better description.
 

TheRaven

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I spent a lot of years drag racing and messing with different fuel types. Even in newer rigs you can get surprising results with different fuels. I had a Ford F150 Screw cab with the 3.5 eco boost. Aftermarket intercooler and tune otherwise stock. It really liked the VP highly oxygenated fuel and would gain 2+ mph through the 1/4 mile over regular pump 93 premium. I used a weather station and kept meticulous notes to ensure true A-B-A testing. So I had a pretty high degree of confidence that the improvement was entirely fuel related. Fuel/octane discussions are always interesting and divisive, lol.
This is precisely why I test every single vehicle I ever purchase. I have a well-developed testing regimen that i've used on every vehicle i've owned in the last 20 years. I know there are vehicles out there that get noticeably better fuel mileage or a significant power boost from higher octane fuel. However, outside of FI engines, I have never been lucky enough to find one of these unicorns.


basically, buried in this thread, there is a tuner in here that showed lots of data and examples specific to these motors running on 87 vs 91 and showed the benefits to the motor while even on the stock tune when it comes to knocking. showed the data logs and all. And one guy here has a major hard on for the owners manual and refuses to believe any data being shown to him about it lol.
This is an almost completely inaccurate description of the thread.
 

LOBBS

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I get around 22 mpg in my JLR with the 3.6L, auto and 35s. Currently still running the 4.10 gears but will be going to 4.56s. Only 89 octane or more since the day that I bought it. My daily commute is 30ish miles each way and roughly 80% highway. Going to 35s, I kept added weight to a minimum by going with KO2s and wheels that were only a pound heavier than the factory Rubicon wheels. I don't use the stop/start but do avoid any unnecessary idling as much as possible and don't do drive thrus.
 

Pinky Tuscadero

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It's 95 cents a gallon more where I am right now, the only time 93 octane came into play as an advantage was hauling something really heavy like another Jeep on a trailer where the power and mpg actually suffered from 88 vs 93, otherwise there has been zero improvement for me even in the 2.0 turbo and my 5.7 Hemi and several of these 3.6's, so I'll stick to the 88
It may be regional though based on altitude or perhaps some folks are comparing crappy gas to good gas
That E-85 made my old 4.7 Ram and 3.6 Grand Caravan run like a rocket though so I got that if available reasonably (2/3 of regular gas is reasonable) as the mpg on E-85 is generally 2/3 of any gas (less energy - although more octane)
You guys get what you want and please quit fighting - it's all good :)
 

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Kreepin1

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You aren't aware of pushrod 3.6l V6s?! And i'm the one who "doesn't know"? Read up.

https://www.google.com/search?q=3.6l+pushrod+motors
LOL! Are you joking? The first result is for GM's LFX V6 which is a DOHC engine. The next couple are Ebay ads that appear to be for Ford Sprints built in Argentina using a 3.6l I6. Then a few more related to the GM LGX, also a DOHC... Maybe you could tell me the make, model and years of production instead?

LOL "It is generally accepted". I love these plays. The attempt to make it seem like what you believe is common knowledge. I dunno, maybe it works sometimes.

Anyway, the first automobile application for OHV was Buick in 1904. OHC was Maudslay in 1902.

https://en.wikipedia.org/wiki/Overhead_valve_engine

https://en.wikipedia.org/wiki/Overhead_camshaft_engine
First lines in the OHC link:
"An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber.[1][2] This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion chamber in the engine block."

See how I made the important part bold for the hard of understanding? Neat huh?

OH wow look at this, FINALLY an attempt at a real discussion. Ok, lets do it.

You say "benefit from premium". I guess that's our issue because our definitions of "benefit" are probably very different. You could say "they will benefit with less knock and better spark advance"...but to me, that's not a benefit. Until I get more power, better efficiency, or some positive effect on longevity...I see no benefit. I'm putting more in (money), I should be getting more out. Perhaps you can convince me of some benefit I haven't thought of outside of those categories?

SMH...for a second I thought you had actually read. Clearly you didn't. I have never said that someone who feels that their engine runs better on premium shouldn't run premium. See, this is the problem. Words have been put in my mouth and opinions have been assigned to me that aren't mine.

You have the wrong impression. Freaking out is not my disposition. SMH is a much better description.
When spark is retarded from it's optimal setting power is reduced and the engine is by definition less efficient. When extra fuel is injected to keep the cats from overheating the engine is using more fuel than it needs and again by definition less efficient. But I don't expect this argument to sway you. You've made up your mind and aren't going to let facts get in the way.

Yep. Weighed, measured, found wanting.
 

TheRaven

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Yep. Weighed, measured, found wanting.
Ok...providing links with proof didn't work (big surprise, it never has). I guess we'll have to go back to grade school for this one.

Since you were able, for about ten seconds, to drop the personal jab attempts and actually discuss the relevant concepts two posts ago, i'm going to go out on a limb and assume that somewhere behind that keyboard of yours is a working brain, as small as it may be. But since you completely failed the basic requirements of READING THE MATERIAL before commenting on it, we gotta go way back here.

How did it all start? This was a thread where the OP asked other guys running premium if they were actually seeing any tangible gains...so how did it come to this? After all, the question was answered definitively in post 54:

https://www.jlwranglerforums.com/forum/threads/3-6-for-those-running-premium-fuel.54123/post-1177443

Well my first post wasn't until 174, where I mentioned my testing regimen on every vehicle i've owned:

https://www.jlwranglerforums.com/forum/threads/3-6-for-those-running-premium-fuel.54123/post-1562352

Then Livernois jumped right in with the absolute gem of a claim that "the JL heavily knocks on 87 octane, and should be on 91+ for all engines. that's why they audibly spark knock with 87.", immediately after I just got done explaining that my JL does not audibly knock AT ALL on 87. My jaw was on the desk at this point, in disbelief that a respected tuner would make such an obviously nonsensical claim. So I called them out on it, as did several other members (and rightfully so cause it's a laughable claim). Many very long-winded posts follow, but the gist of it is that they were unable to prove the claim - they DID NOT provide any proof of HP, MPG, or longevity gains from running premium. Only a bunch of data about knock and timing advance, which I never once disputed.

Problem is this - it doesn't take an engineer or veteran car guy to identify "audible spark knock", the majority of members posting in this thread can do it. We would know if we were experiencing problematic knock. We also know that modern engine management systems are designed to manage knock as one of their most basic functions....i mean it's the basis of how modern computer-managed timing systems operate - advance spark until knock is detected, then back off spark. The computer does these calculations thousands of times per second...it will quell knock before even the most keen ear could detect it. So if Livernois is actually experiencing audible spark knock then they have a problem with their test engine(s) or they borked something up. That's not something a smart business wants to advertise on a forum of potential long-time customers., and this is why I was completely blown away when I read that comment. Not good advertising.

So the above discussion is what you decided to insert yourself into, leading with a misinterpretation of a general comment I made that isn't even relevant to this discussion and THE EXACT SAME INFORMATION THAT LIVERNOIS POSTED AND I ALREADY SAID 20+ TIMES THAT I DON"T DISPUTE. We can stop talking about how the JL knocks more on 87 than on 93, it's been established and absolutely no one is disputing it.

So...now that you have the information you need to approach this discussion, do you want to bring something new to the table? Perhaps some kind of proof that the JL does in fact get better fuel mileage, offers appreciably better performance, or will last longer if we run premium? Or do you just want to waste more datacenter storage space on irrelevant conversations about old engines and things we agree on?
 

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For those running premium fuel, what are you seeing (MPG increase and overall improvements if any).

I’m seeing the 3.6 is 11.5:1 compression, and more and more forum discussions for other vehicles that run the Pentastar are using premium with good success.

weather and wind have been fairly consistent here in NE Ohio and over the last 6 days I ran through 2 tanks, seeing just over 3 MPG better on highway runs back and forth to the same place helping my father in law move his inventory from a Snap On truck.

was getting 17 to 17.5 MPG andover the last two tanks of premium have been seeing 20.7 to 21.1. Didn’t have any knock issues or anything before this so running performance (if you can call the Wrangler anything performance related) hasn’t changed much.

Just interested in other feedback.
changed over to 90 pus octane a year back because the recommended chrysler 87 octane was pinging all the time, this was always below the 2000 rpm limit. I've done a few mpg test on mine a while back and there didn't seem to be difference in the octane rating and mpgs....as far as I could tell. Mine gets me about 27mpgs at highway legal speed ..usually around 60mph . If anything 87 octane has a more powerfull explosion in combustion chamber which would to a certain degree increase mpgs ..but theres also CR ratio one has to take into account. If ur pinging then there would be an advantage to the higher octane ..as the condition actually makes the engine lose power
 

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I don’t know the cause of your 3+ MPG fuel efficiency increase, but it’s not from using higher octane fuel. It’s not physically possible. It’s great to use if you have knocking, but it doesn’t increase fuel mileage.

But it’s your money and if you lbelieve that it does, who am I and the laws of thermodynamics to tell you different.
This has historically been the case.

But modern engines dynamically adjust ignition advance based on detonation events.

If premium allows the engine to run more advance then its thermodynamic efficiency improves. So some fuel economy improvement could be seen.
 

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Ok...providing links with proof didn't work (big surprise, it never has). I guess we'll have to go back to grade school for this one.

Since you were able, for about ten seconds, to drop the personal jab attempts and actually discuss the relevant concepts two posts ago, i'm going to go out on a limb and assume that somewhere behind that keyboard of yours is a working brain, as small as it may be. But since you completely failed the basic requirements of READING THE MATERIAL before commenting on it, we gotta go way back here.

How did it all start? This was a thread where the OP asked other guys running premium if they were actually seeing any tangible gains...so how did it come to this? After all, the question was answered definitively in post 54:

https://www.jlwranglerforums.com/forum/threads/3-6-for-those-running-premium-fuel.54123/post-1177443

Well my first post wasn't until 174, where I mentioned my testing regimen on every vehicle i've owned:

https://www.jlwranglerforums.com/forum/threads/3-6-for-those-running-premium-fuel.54123/post-1562352

Then Livernois jumped right in with the absolute gem of a claim that "the JL heavily knocks on 87 octane, and should be on 91+ for all engines. that's why they audibly spark knock with 87.", immediately after I just got done explaining that my JL does not audibly knock AT ALL on 87. My jaw was on the desk at this point, in disbelief that a respected tuner would make such an obviously nonsensical claim. So I called them out on it, as did several other members (and rightfully so cause it's a laughable claim). Many very long-winded posts follow, but the gist of it is that they were unable to prove the claim - they DID NOT provide any proof of HP, MPG, or longevity gains from running premium. Only a bunch of data about knock and timing advance, which I never once disputed.

Problem is this - it doesn't take an engineer or veteran car guy to identify "audible spark knock", the majority of members posting in this thread can do it. We would know if we were experiencing problematic knock. We also know that modern engine management systems are designed to manage knock as one of their most basic functions....i mean it's the basis of how modern computer-managed timing systems operate - advance spark until knock is detected, then back off spark. The computer does these calculations thousands of times per second...it will quell knock before even the most keen ear could detect it. So if Livernois is actually experiencing audible spark knock then they have a problem with their test engine(s) or they borked something up. That's not something a smart business wants to advertise on a forum of potential long-time customers., and this is why I was completely blown away when I read that comment. Not good advertising.

So the above discussion is what you decided to insert yourself into, leading with a misinterpretation of a general comment I made that isn't even relevant to this discussion and THE EXACT SAME INFORMATION THAT LIVERNOIS POSTED AND I ALREADY SAID 20+ TIMES THAT I DON"T DISPUTE. We can stop talking about how the JL knocks more on 87 than on 93, it's been established and absolutely no one is disputing it.

So...now that you have the information you need to approach this discussion, do you want to bring something new to the table? Perhaps some kind of proof that the JL does in fact get better fuel mileage, offers appreciably better performance, or will last longer if we run premium? Or do you just want to waste more datacenter storage space on irrelevant conversations about old engines and things we agree on?
I think an unbiased reader would conclude that you are the one most prone to personal to personal attacks. Further, those "links with proof" were just the opposite; either irrelevant or proving my points. But lets set that aside and focus on the technical discussion.

What you are seeing in this thread are two different sets of experience. Group A are typical drivers who may or may not notice their engine runs better on premium but notices no difference in performance or fuel economy. Group B are people with technical backgrounds and/or experience hot rodding engines who note power increases and explain how spark retard reduces thermodynamic efficiency and can lead to other long term problems.

Why this difference? Shouldn't the science Group B is explaining translate to real world gains Group A notices? The reason is twofold. First, it is not possible to detect the power changes with your butt dyno. Perhaps the next time you test your car you should add drag strip testing to your procedure (you will need to account for weather variations). Time slips don't lie. Second, very little of a typical driver's time is spent near full throttle which is the only time spark is retarded. Under high to moderate manifold vacuum (idle and cruise) the engine does not experience knock, spark is not retarded, and under these conditions there will be no difference in fuel economy between regular and premium assuming the same ethanol percentage. So Group B is saying "there is an increase in efficiency" and Group A is saying "I can't measure it" and both are right.

Of course, I have a very small brain, so I could be wrong...
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