I don't think premium gas does any good unless you are tuning. There isn't a real tune available for 2013's yet (or Mopar '11's). IMO, you're better off using mid-grade, as recommended per Dodge.

 

I had to use premium in my GTP for 10 years and I am used to pumping that. Also, they have no ethanol here so that is what I use in my Charger.

 

I am running the Diablo sport 91 octane tune, and run 93 religiously. Last thing I want is a problem with knock and I figure the extra pennies are worth the piece of mind. Even stock I ran at least 89. Same reason. that and if you read the manual 89 is recommended.

Jeff

 

running 87 octane regular...haven't seen any difference in performance or fuel economy vs. 89....owners manual states 89 recommended, 87 acceptible....running higher is just wasted money

 

89 here which is mid grade. 87 is regular in NJ.

 

I do not want to scue your stats but yes in my 6.1l Hemi I run Primium and if I do nor run it, I can tell the difference... I will not vote due to you wanted 5.7 Hemi.

 

I use 89 ( Mid Grade Here ) since the maual states to use it. When I finally do a DS 93 Tune, I will run 93 ( Which is Premium here )

 

I ve run 93 since day one(oct '05) with the exception of 1 tank. I wanna say it knocked a little more but but i dont know. It was a long time ago. One thing that i have noticed though is the condition of my plugs compared to people's that run mid grade and half the distance. I forgot to change mine once and went 60k on one set. When they came out, they looked new except for the obvious signs of heat. I've gone through 3 sets now and its been the same each time. If the 93 has the same effect on the valves and injectors; I'm ok with spending the extra money. I'm not planning on parking it anytime soon. Im having too much fun.

 

Never put anything but 93 in my car. That with ACES IV in the gas tank. I don't notice anything from a standstill, but accelerating while on the highway is extremely noticeable when i've got ACES IV and when I filled up without. I think BND claims ACES increases octane to 101 when filled with 93? not completely sure of the number.

 

running 87 octane regular...haven't seen any difference in performance or fuel economy vs. 89....owners manual states 89 recommended, 87 acceptible....running higher is just wasted money

^ this
.........

 

To me premium gas is a much cleaner gas..
ALWAYS used it on my 2007 RT and I use it on my 2012 SRT. I always used it on my wife's car a Nissan Juke 1.8L engine.... Cleaner Gas means better mileage and keeps your motor running cleaner.. When you do the math you are not paying that much of a difference for better gas..

 

To me premium gas is a much cleaner gas..
ALWAYS used it on my 2007 RT and I use it on my 2012 SRT. I always used it on my wife's car a Nissan Juke 1.8L engine.... Cleaner Gas means better mileage and keeps your motor running cleaner.. When you do the math you are not paying that much of a difference for better gas..

^^^ Yes sir you stand correct. Here is why. The higher the octane number, the more compression the fuel can withstand before detonating. In broad terms, fuels with a higher octane rating are used in high-compression engines that generally have higher performance. Use of gasoline with less octane numbers may lead to the problem ofhttp://en.wikipedia.org/wiki/Octane_rating#cite_note-Ullmann-1 engine knocking. When engine knocking occurs it cause the precise timing of the spark plug and piston stroke cycle. In others words short stroking the engine. The air fuel mixture is ignited by the spark plug so if there a delay there you will not get the full output of the engine.

Think of it this way... Your heart is the core of you body. Your car engine is the core of the car. If something is affect your heart you body reacts. Same goes with your car engine. If your putting 89 in your car, but their a lot of dilution in it then yes you may think it's shitty gas. Then you switch to 87 and you getting better gas mileage. Often shitty gas station will have quality 87, but not 89. The common consumer uses 87 so they either pretend to run 89. When it's really 87. It's cheaper on them. So my suggestion is take a jar and test the gas. When you find a quality gas station stick with it. Now you can't do this to every gas station if say your on the road, but I usually go with shell gas. A common and very popular gas station. Not saying all shell gas is good, but I trust it over many other places. I would also suggest Chevon and Exxon Mobile. One of the only ones left that run their own rigs. I just don't trust BP anymore after there incident.

Also if your a V-8 or + owner and your worry about gas mileage. I'm sorry I think you purchased the wrong car. Should of stuck with a 4 cylinder or bought a V-6 model Charger. Not bashing V-6 because I liked my 2011 Charger SE and there still great cars and have some nice power, but I love my 2012 Charger R/T and as long as I can prevent it will never go back. Either suck it up and pay the bucks or switch back to a lesser cylinder car. If you actually care for your car then you'll do whatever you can do to make those babies last. That's why 4 decades later you still seeing 1970 Chargers. Just saying. Till next time fellas.

 

I'm running the DS Trinity tune, so I run 93 octane! Before the tune, I ran 89 as recommended.

 

89 before Diablo tuning. 93 now. Why pay the premium for a 370 hp V8 and then take away some power by running lower octane? You gotta pay to play.

An excerpt from a guy much smarter than me:

"Production engines are optimized for the type or grade of fuel that the marketplace desires or offers. Engine designers use the term called MBT ( Minimum spark for Best Torque) for efficiency and maximum power; it is desirable to operate at MBT at all times. For example, let's pick a specific engine operating point, 4000 RPM, WOT, 98 kPa MAP. At that operating point with the engine on the dynamometer and using non-knocking fuel, we adjust the spark advance. There is going to be a point where the power is the greatest. Less spark than that, the power falls off, more spark advance than that, you don't get any additional power.

Now our engine was initially designed for premium fuel and was calibrated for 20 degrees of spark advance. Suppose we put regular fuel in the engine and it spark knocks at 20 degrees? We back off the timing down to 10 degrees to get the detonation to stop. It doesn't detonate any more, but with 10 degrees of spark retard, the engine is not optimized anymore. The engine now suffers about a 5-6 percent loss in torque output. That's an unacceptable situation. To optimize for regular fuel engine designers will lower the compression ratio to allow an increase in the spark advance to MBT. The result, typically, is only a 1-2 percent torque loss by lowering the compression. This is a better trade-off. Engine test data determines how much compression an engine can have and run at the optimum spark advance."

 

The above is probably true. However, it's my understanding that the 5.7 hemi is optimized to run on 89 octane gas. Putting 91 or 93 octane gas in without a tune will not create additional power as the stock PCM does not adjust to having higher octane.

As others have stated, the higher octane gas may be cleaner, but a good quality gasoline already has cleaners/additives in it. Bottom line, run whatever you want. I will not run 87 octane, but I see no need to run 91 octane as I cannot tune my car.

Tuning is a different story.

 

The above is probably true. However, it's my understanding that the 5.7 hemi is optimized to run on 89 octane gas. Putting 91 or 93 octane gas in without a tune will not create additional power as the stock PCM does not adjust to having higher octane.

As others have stated, the higher octane gas may be cleaner, but a good quality gasoline already has cleaners/additives in it. Bottom line, run whatever you want. I will not run 87 octane, but I see no need to run 91 octane as I cannot tune my car.

Tuning is a different story.

Yes sir you stand correct as well....Here is another more detailed reason why....

We all know, or some of us know that you PCM controls you electrical timing. When you purchase your cars it already set to a certain Octane level. In a 5.7L it's set to 89. Also the higher the Octane the more combustible it is. Cars with longer Cylinders such as ours require a certain Octane level to create more power. So if you put a higher octane level when it isn't necessary it doesn't effect the PCM because the PCM controls the timing and fire order so it will not cause the problem with the timing of the cyclinders. So what happens instead is excess carbon begins to build up on the piston rings which then cause them to stick. Which then cause the term blow by which is the engine burning oil and fuel which will eventually cause poor performance.

Now with a tune yes it will change the setting of the PCM. That's why your able to supposedly run 91,92,93 octane and so on also the reason why we could not run the previously used tuners unless we switched out the PCMs for the cars...but if your engine's octane level is maxed at 91 then anything higher then that is actually damaging the performance of the engine. Now maybe at first your getting great results with a higher octane level because you running a higher combustible fuel, but eventually through time it was cause severe engine casualty. So to me tunes are great, but if misused properly then your only damaging your car.

Honestly my thoughts I don't think a 5.7L with a tune can handle anything higher then 91 Octane without switching out fuel injectors and several other parts. Now once you switch these items out then yes I think it can properly run correctly. But hey use at your own risk...

 

My mom uses 87 in her Overland which recommends 89. No problems so far.

If I had a Hemi of my own, I would run the recommended fuel for it... just because it is "recommended".
I ran 87 in my 4.7 stroker I6 on my Jeep Cherokee and 89 was recommended.
I detonated so bad it destroyed the pistons.

 

Yes sir you stand correct as well....Here is another more detailed reason why....

We all know, or some of us know that you PCM controls you electrical timing. When you purchase your cars it already set to a certain Octane level. In a 5.7L it's set to 89. Also the higher the Octane the more combustible it is. Cars with longer Cylinders such as ours require a certain Octane level to create more power. So if you put a higher octane level when it isn't necessary it doesn't effect the PCM because the PCM controls the timing and fire order so it will not cause the problem with the timing of the cyclinders. So what happens instead is excess carbon begins to build up on the piston rings which then cause them to stick. Which then cause the term blow by which is the engine burning oil and fuel which will eventually cause poor performance.

[snip]

Honestly my thoughts I don't think a 5.7L with a tune can handle anything higher then 91 Octane without switching out fuel injectors and several other parts. Now once you switch these items out then yes I think it can properly run correctly. But hey use at your own risk...

Technically this Octane rating is a measure of burn rate. a higher octane fuel burns slower and is *less* combustible--more resistant to premature detonatiion caused by heat and pressure.

while some of the things you mention could theoretically happen, I suppose, what is more likely to happen running 92 or 93 with a stock tune is the fuel doesn't burn quite as fast, so you won't generate max cylinder pressure, and won't make max power, as the air/fuel mixture might still be burning well after TDC & beyond as cylinder volume is expanding as the piston moves down, possibly even to the point where the exhaust valve is opening, which just makes it wasted energy

for the most part, all a tune for a higher octane does is add spark advance to light the fuel earlier, to allow full burn and max cylinder pressure to generate the most power. injector sizing of a stock motor won't really affect that, unless they're undersized to begin with, and 93 vs. 91 octane isn't going to be such a huge difference to cross that threshhold. the genIII Hemi combustion chambers and dual plug design is very efficient from a combustion burn standpoint, and it doesn't need a lot of spark advance to get complete burn....maybe 20-25 degrees (compared so some older V8's that needed 40+ degrees)...adding too much spark advance will begin to diminish power, as then you'll be working against the piston on the upward compression stroke too much, which might be the case if you had a stock 5.7 and tuned for max ignition advance for say 110 octane race fuel...

 

People think high octane means more energy in the fuel. It doesn't. Higher octane fuel has less energy and will give you poorer gas mileage. It has a higher flash point allowing more compression heat before detonation. The octane makes the gas harder to light. It takes a higher temperature to ignite thus it has less energy. What higher octane fuel does allow is much higher compression ratios and can create crazy horse power in an engine designed for it. Unless you really need the few percent extra HP anything above regular is a waist of money. Not only does higher octane cost more it has less energy when used in an engine with normal compression. I use mid-grade when I test 0-60 with Torque Pro but run regular most of the time. The big oil companies love to make people think higher octane will make your car go faster because they can buy bigger houses and boats. What you want to look for is TOP TIER fuel. Top Tier fuel has more detergents and will keep things much cleaner. Look for the Top Tier sticker or do a web search to fine gas retailers in your area that have Top Tier fuel, buy mid-grade when you want to smoke the tires and regular for everyday driving.