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Random question, but I was driving my car the other day and realized that I needed to get some gas soon. Is there any benefit to using 93 octane on a COMPLETELY stock mustang vs 87 octane? Just wondering. Thanks!
 

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The "STOCK" mustang is by design, completely efficient on the lower octane fuels. This, after all, is a daily driver. The higher octane fuels will produce an improved performance characteristic, but almost unrecognizable performance, disregarding track times perhaps. Don't waste your money for a daily "Stock" driver. Once you add some mods, the equation changes.
 

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I would disagree, the car will get more MPG and run better on the higher octane...do a study sometime and prove it to yourself
 

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I would disagree, the car will get more MPG and run better on the higher octane...do a study sometime and prove it to yourself
Um, exactly how?

The only difference between 87 and 93 octane is 93 has a higher resistance to detonation. It doesn't have more potential-energy. :nono:

A stock Mustang does not have fuel and timing maps to run higher octane. It will go to waste.
 

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Um, exactly how?

The only difference between 87 and 93 octane is 93 has a higher resistance to detonation. It doesn't have more potential-energy.

A stock Mustang does not have fuel and timing maps to run higher octane. It will go to waste.
Unless you are talking about 2010 or later, those have adaptive spark timing that will take advantage of the higher octane.

To the OP, like Nick said, it will not make any difference unless your car is tuned for the 93 Octane, in which case you should not be using 87 because it will "ping" or "knock" or "detonate" (different words for the same thing)

Some say it will actually leave carbon deposits because the higher octane burns slower and may not burn completely unless the spark is advanced (that's what the tune does)

I guess it might be worth a test like 2manystangs suggests, but I think you will find it makes no difference.
 

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Unless you are talking about 2010 or later, those have adaptive spark timing that will take advantage of the higher octane.

To the OP, like Nick said, it will not make any difference unless your car is tuned for the 93 Octane, in which case you should not be using 87 because it will "ping" or "knock" or "detonate" (different words for the same thing)

Some say it will actually leave carbon deposits because the higher octane burns slower and may not burn completely unless the spark is advanced (that's what the tune does)

I guess it might be worth a test like 2manystangs suggests, but I think you will find it makes no difference.

Right, I wasn't exactly sure when they put that in.
 

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well I can tell you 1st hand my father had a stock Crown Vic 4.6...he was complaining about the performance...yeah he used crappy 87 Rally gas...I had him try tanks of 93...now he's a total scientist and did the math, he conclusively found the car ran better and got better milage which offset most of the added expense.
 

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well I can tell you 1st hand my father had a stock Crown Vic 4.6...he was complaining about the performance...yeah he used crappy 87 Rally gas...I had him try tanks of 93...now he's a total scientist and did the math, he conclusively found the car ran better and got better milage which offset most of the added expense.
I would put that on either getting bad gas, or the 87 gas having more ethanol.


Ethanol is something like 30% less potential energy than gasoline. This means the more Ethanol you have, the less power you make, and the worse MPG's you'll get. Ethanol is good for one thing, making BIG power on boosted applications. It's something like 104(?) octane, meaning you can run a lot of boost with a lot of timing on it.
 

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I don't want an on-line debate about credentials but it looks like 2manystangs asked for it... I am a multi licensed, qualified, design engineer, with a specialty in powerplants, with over 20 years experience in concept to production products....this includes Automotive and more specifically Aviation. Fuel burn is one of my specialities. Sorry my friend, but if your Papa noticed some Euphoric event with his classic car, I can tell you honestly from a scientific point of view, that automotive manufacturers are interested in putting cars in the hands of the masses at the cheapest price, and they factor in the cost of fuel. There is no ROI for an owner operating a vehicle designed for 87 octane, to use a higher octane fuel and expect this fuel to provide a significant improvement in performance that is measurable by the average driver. Perhaps "Papa" still thinks Santa Claus is real too.
 

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Actually they tested the 05GT back when it came out due to the VVT. They took a stock 05 GT and tested with 87. got a base line. Then drained it and put 91 octane in it and it got 5 more rwhp. They also tried it on the 05 V6, which doesn't have vvt, it actually lost a few rwhp.
So, the 05 and up GT's, yes you can get a small gain by using 91 or 93 but probably not worth the cost. pre 05, i wouldn't use it at all unless you have to use it due to a tune or running a higher compression motor.
People that have cars that would need to be tuned for it...if you don't have a tune, it's a waste. If you have cats, the unburned gas could destroy them. Also due to the unburned gas, you won't get better mpg and your performance could be lacking.
why this question still comes up...i have no idea.
 

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I don't want an on-line debate about credentials but it looks like 2manystangs asked for it... I am a multi licensed, qualified, design engineer, with a specialty in powerplants, with over 20 years experience in concept to production products....this includes Automotive and more specifically Aviation. Fuel burn is one of my specialities. Sorry my friend, but if your Papa noticed some Euphoric event with his classic car, I can tell you honestly from a scientific point of view, that automotive manufacturers are interested in putting cars in the hands of the masses at the cheapest price, and they factor in the cost of fuel. There is no ROI for an owner operating a vehicle designed for 87 octane, to use a higher octane fuel and expect this fuel to provide a significant improvement in performance that is measurable by the average driver. Perhaps "Papa" still thinks Santa Claus is real too.
I just wasted 30 seconds of my life reading this. how about you post the facts and not crap about what you think you know.
 

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According to your post and facts which are supported by no documented fact or point of reference......if you seriously think you can convince any one that you can "FEEL" a 5 HP gain....you are foolish, this must be a joke...........5HP....Yeah man ....can you feel it.... awesome ......I am so fast now........c'mon.....Really!!!!
 

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Actually they tested the 05GT back when it came out due to the VVT. They took a stock 05 GT and tested with 87. got a base line. Then drained it and put 91 octane in it and it got 5 more rwhp. They also tried it on the 05 V6, which doesn't have vvt, it actually lost a few rwhp.-...]
Where did "they" publish their results?
 

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Sorry....but read this as if you are happy.....I thought about this... and let me put this in perspective. There is a piece of string and it is 1 meter long. I:) grab one end and you grab the other. Then I fart. Did you feel that? Probably not....just like a 5 HP gain.....again, apologies, but it is kinda funny.
 

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Actually they tested the 05GT back when it came out due to the VVT. They took a stock 05 GT and tested with 87. got a base line. Then drained it and put 91 octane in it and it got 5 more rwhp. They also tried it on the 05 V6, which doesn't have vvt, it actually lost a few rwhp.
So, the 05 and up GT's, yes you can get a small gain by using 91 or 93 but probably not worth the cost. pre 05, i wouldn't use it at all unless you have to use it due to a tune or running a higher compression motor.
How many times did they run it on the dyno with each grade of gas? Was it just one run with each grade? Three runs? I wouldn't be surprised to see a few hp (or more) margin of error on either side just between runs.
 

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I don't want an on-line debate about credentials but it looks like 2manystangs asked for it... I am a multi licensed, qualified, design engineer, with a specialty in powerplants, with over 20 years experience in concept to production products....this includes Automotive and more specifically Aviation. Fuel burn is one of my specialities. Sorry my friend, but if your Papa noticed some Euphoric event with his classic car, I can tell you honestly from a scientific point of view, that automotive manufacturers are interested in putting cars in the hands of the masses at the cheapest price, and they factor in the cost of fuel. There is no ROI for an owner operating a vehicle designed for 87 octane, to use a higher octane fuel and expect this fuel to provide a significant improvement in performance that is measurable by the average driver. Perhaps "Papa" still thinks Santa Claus is real too.
well my father has infinitely more education and experience than you(masters in physics and EE, also with Army metrology and calibration for 40 years), maybe you should do some real world testing before just slamming someone you don't even know, his car wasn't a jalopy, it was a mid 90s crown vic with the 4.6, an engine like very similar to what most of us drive..
Now your point that somehow the OEMs "scientifically" put cars in the hands or people for the lowest price is the stupidest thing I've ever read and shows you know nothing about sales or marketing, typical of the engineer set...why would they even build a V8? Why would they require premium fuel? How could Bugatti even exist? Maybe you should check the ventilation in your lab, you've inhaled too much fuel vapor and are delirious.
 

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Blazin 72 you are an educated person. A basic fundamental of probability is the outcome of cumulative result. The variable of chance is eliminated with repetitive test results. Thank you for your insight. You Sir are worthy of a bow.
 

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I don't want an on-line debate about credentials but it looks like 2manystangs asked for it... I am a multi licensed, qualified, design engineer, with a specialty in powerplants, with over 20 years experience in concept to production products....this includes Automotive and more specifically Aviation. Fuel burn is one of my specialities. Sorry my friend, but if your Papa noticed some Euphoric event with his classic car, I can tell you honestly from a scientific point of view, that automotive manufacturers are interested in putting cars in the hands of the masses at the cheapest price, and they factor in the cost of fuel. There is no ROI for an owner operating a vehicle designed for 87 octane, to use a higher octane fuel and expect this fuel to provide a significant improvement in performance that is measurable by the average driver. Perhaps "Papa" still thinks Santa Claus is real too.
Don't come onto this forum and start firing off nukes, rookie.

2ManyStangs was just trying to help. Whether he's right or wrong, at least he has the right intentions. I personally know that 2manystangs is a good person, and is only out here on this forum to help others. I can't say that about you....

The people on here are mostly smart people, who want to help others enjoy their Mustangs as much as possible. I don't respect people who slam on others with no factual basis. I bet you had no clue what would really happen if you put 93 in a stock stang. Yes, your guess was correct, but I really don't think you knew for sure. News flash, it's all in the tune. All you do is change timing and fuel tables and you have a car that will gain power from higher octane fuels. This OP was not about how fuel reacts in a generic engine, but how a SPECIFIC car will react to a different fuel type.

You don't need credentials to know a little about cars, and tuning. I haven't had a single class, yet for some reason I still know way more about 05-10 Mustangs than you do.

We here at AFM are a community, who pride on respecting and helping others. If you cannot abide by those simple rules, Get Out. :nono:
 

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Hi 2manystangs!!!

In fact, I hold a doctorate degree in science and studied under Dr. Martin Pearl, who is a Nobel Prize recipient if we are comparing qualifications, I was also a guest speaker at the Festival of Thinkers.....google that..... go ahead....google it. I apologize if I upset you....but I have no time for ignorance and this will be my last direct communication to you
 

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Hello Nick F

Kindly allow me to explain. If you look back at the responses, 2manymustangs provides fact with no support to them. No one should ever accept information at face value. He challenged me and I responded. Yes, I am a "Rookie" here, but I have over 20 years experience in this subject. Am I still a rookie??? On the forum, yes.....in life NO. In fact I tune the cars at Yas Marina Circuit....go ahead.....google it....I do stangs, Lambos, corvettes, Jaguar, ferrari, and yes bentleys.......so my new friend...apologies for what you see as coming on strong....but hey, that is me, a stone head with the ability to learn...and with that, I thank you
 
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