3.6 - For Those Running Premium Fuel

[geem03]

I noticed with my 3.6 manual that I gas up less since I started using high octane these last few weeks....coincidence?...I think not...

But I have no scientific background or data to prove or disprove this occurrence.... just what I've noticed.

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[Chocolate Thunder]

Children. Personal insults and lack of respect for opposing views heavily clouds any intelligence you may bring to the table. Hard to learn when one has to sift through the BS to get to actual facts and experience.

I tuned out quite a while ago as these threads ALWAYS end up going there. So give me the TLDR synopsis: who had the bigger Johnson?

 

[firedude]

This is the best thing in this thread by far. I bet the Stang was running on 92 octane.

 

[1BadManVan]

This is the best thing in this thread by far. I bet the Stang was running on 92 octane.

nah, E85 I heard

 

[TheRaven]

I tuned out quite a while ago as these threads ALWAYS end up going there. So give me the TLDR synopsis: who had the bigger Johnson?

This, and 3.6l vs 2.0l. Not things you'd expect Jeep guys to get really defensive about, but it's tough for me to think of anything that gets Jeep guys more riled up...questioning the obvious superiority of the 2.0 or daring to run regular fuel.

Oh and if we had big johnsons, we'd be far too busy for these discussions.

that's why I utilized the ignore button on that one certain member. Its a shame people stoop to these levels though over a subject like this.

You are one of the "children" he's referring to. It is a shame though.

 

[Snazzy Jeep]

I'm just a newbie to jeep life, but I can get 90 octane non-ethanol here. I ocassionally used it until gas went sky high. I would run the tank to nearly empty and fill it up. I did notice an increase in both power and mileage when I used it. I wish I had taken a picture of the gauge on our jeep the other week, we had to drive through Atlanta at 50 MPH the whole way, our mileage showed 24.5 on our 3.6 etorque. yes, we were driving modestly. I generally get pretty good mileage unless we are in 4wd in the back mountains where we live. Just my experience. we now have 15,100 miles on the jeep.

 

[Steph1]

Haven’t seen any mpg gains, but engine definitly runs smoother. However, with the price of gas these days, It will have to get used to regular gas, at least for a while.

 

[jaymz]

There is a surprising number of guys here who seem to be in the wrong profession - if you know better than the engineers that built and tested these motors over thousands of miles, you should be applying for their jobs. You'd almost definitely be making more money than whatever you are doing now.

It's not necessarily that anyone knows better than the OEM engineers. It's that they aren't constrained by the corporate bean counters to the same extent as OEM engineers are. There are gains to be had due to that fact. Sometimes significant, sometimes not.

No matter which way you go, when you buy a vehicle, you put "blind faith" in engineers. When you purchase an aftermarket modification, you put "blind faith" in the people who created it - who more often than not aren't even engineers - they're tinkerers or even just salesmen. So you're done trusting the professional creators of the vehicle you paid $40k+ for, now you're going to trust this one guy with a very convincing sales pitch. That makes total sense.

Smokey Yunick was not an engineer - just a tinkerer. And he was known as a genius in the automotive performance circles. I'd trust what he'd have to say as much, if not more, than a professional creator.

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?

Why would "less knock and better spark advance" not be a benefit? Both of those things by definition are beneficial.

 

[TheRaven]

There are gains to be had due to that fact. Sometimes significant, sometimes not.

Can't disagree there. Sometimes there ARE benefits to be gained...I actually said that a few posts ago. I just have yet to find a vehicle that DOES benefit in any significant way.

Smokey Yunick was not an engineer - just a tinkerer. And he was known as a genius in the automotive performance circles. I'd trust what he'd have to say as much, if not more, than a professional creator.

Fair statement...problem is that here we are not talking about an automotive "genius" vs a professional. We are talking about a random dude at a small aftermarket outfit vs. a team of career professionals following long established controls and procedures. I am an engineer myself and I know the kind of work I and my team put into our development projects. So I trust other teams like my own over random dudes I don't know. Now if those random dudes can put forth some results, then i'll take a look, and judge for myself.

Why would "less knock and better spark advance" not be a benefit? Both of those things by definition are beneficial.

Yes...and this was also addressed. I have never said those things are NOT a benefit. What I have been trying to explain is that they are not the kind of benefit necessary to justify an additional $800 per year in fuel costs. The question posed in this thread is whether or not it's WORTH running premium...meaning is there a return on the "investment"? In this case, the answer is no. That's it.

 

[wsly14]

I’m interested in trying this out for myself. I’ve been running 87 octane for the last 3000 miles and haven’t noticed any knocking or issues, but I’m curious to see if anything noticeable happens by switching to 91. (Whether it’s worth the cost is a separate debate IMO)

I was thinking of disconnecting the battery and touching the + and - cables together to reset the ECU upon switching fuels. I’m hoping this will allow the ECU to readjust to the higher octane fuel more quickly. I think switching fuel without some kind of reset will leave the ECU calibrated for 87 octane. I can see how the ECU would automatically adjust parameters when going from 91 to 87 octane, but not sure it would adjust as much when making the switch the opposite way.

Does this make sense?

 

[TheRaven]

I’m interested in trying this out for myself. I’ve been running 87 octane for the last 3000 miles and haven’t noticed any knocking or issues, but I’m curious to see if anything noticeable happens by switching to 91. (Whether it’s worth the cost is a separate debate IMO)

I was thinking of disconnecting the battery and touching the + and - cables together to reset the ECU upon switching fuels. I’m hoping this will allow the ECU to readjust to the higher octane fuel more quickly. I think switching fuel without some kind of reset will leave the ECU calibrated for 87 octane. I can see how the ECU would automatically adjust parameters when going from 91 to 87 octane, but not sure it would adjust as much when making the switch the opposite way.

Does this make sense?

I absolutely recommend trying it for yourself. Going on the advice of a bunch of random guys you don't know on an internet forum (or even a random guy from a small tuning outfit) is never a great idea...too many variations in driving habits, environment, weather...etc. It's different for everyone.

Also, the ECM WILL adjust to the new fuel grade regardless of if you reset it or not. HOWEVER, if you do a manual reset, it should give you faster results. The ECM "learning" process is pretty slow, and that can be frustrating when you just want to answer a question that costs you money.

 

[JeepinJason33]

No problem with 85 here in Denver thanks to the altitude. For two months I had the same 150 mile commute several days a week. I ran 85 the first month and 89 the next month and did not notice a measurable increase in mpg. No pings at 85 and that is what the dealer is actually putting in their vehicles so I am going to keep running it.

 

[1BadManVan]

No problem with 85 here in Denver thanks to the altitude. For two months I had the same 150 mile commute several days a week. I ran 85 the first month and 89 the next month and did not notice a measurable increase in mpg. No pings at 85 and that is what the dealer is actually putting in their vehicles so I am going to keep running it.

Altitude definitely plays a role for sure. We live at sea level and definitely notice the difference running 91

 

[jeepdabest]

 

[TaiMc]

This is the best thing in this thread by far. I bet the Stang was running on 92 octane.

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