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Discussion Starter · #1 ·
What Octane is everyone running in the 2013 GT? Cause owners manual calls for 87 and higher octanes for higher performance and heavy duty usage which is obvious. But I called and talked to a tech at a big ford dealership here in my area and he suggested running 87 and that 91 could cause rough starts and what not. Anyway any info on this topic is greatly appreciated.
 

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Just like i watch what i eat to stay healthy i do the same with my car and put 93 octane since day one.
 

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91 is the highest available where I live and I've never ran anything else in my 2013 mustang! Picture perfect performance so far!

edit: Non track pack auto GT vert here.
 

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I run 91 on the weekends and 87 during the week. Zero problems. I also try to change up the gas stations that I fill up at. Different gas (chevron/shell/texaco) different detergents cleaning. At least that is how I have always understood it.
 

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The Blue Dragon
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The dealer needs to fire that technician. A high compression motor needs to run higher octane fuel. Yea yea, variable can timing, knock sensors, blah blah blah... Run high octane fuel. Those things are fail safe devices to prevent the motor from damage, not even sure why ford would recommend anything less than premium. Probably just to maintain a low cost of ownership.

Track pack or not doesn't matter. Still the same motor
 

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You always want to run as little octane as the car will allow you to run. Less octane = more energy. More octane allows the fuel to burn slower and cooler which allows you to push the car to it's limits and minimize the risk of detonation. The factory detune's our cars so much that there is no benefit to running a high octane fuel until you tune the car for a higher octane by advancing timing and what not.

I'm still learning about the Coyote motor but I know that many cars that are tuned to run 87 octane fuel from the factory can actually have their performance hurt by running a higher octane fuel. Many cars are designed to advance the ignition timing on start up until the knock sensor detects knock, if you run a high octane fuel the knock sensor will not detect any knock and will pull ignition timing all the way back because it assumes something is wrong and the car needs to run in a safe mode.

If you want to get the most out of your car drop a few hundred bucks on a tuner from American muscle and run a 93 octane tune.
 

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Discussion Starter · #10 ·
I went to the ford website and it specifically says to run premium unleaded fuel in the GT 5.0, Boss 302, and Shelby GT500 5.7, the only new mustang that it said to run regular unleaded is the new V6. So I am running premium, that's what ford says to do on their website. So from my understanding you can run 87 and have no problems because these newer motors are designed to run on it as well but premium will give you optimum performance and MPG.
 

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Discussion Starter · #11 ·
I have attached here the link to the FORD website regarding 2013 Mustang engine specs if anyone is curious. If you look at recommended fuel fuel for the 13' GT you will see what I was talking about in the last message. So as I said I'm running premium fuel, no matter people are saying about 87 octane being the recommended fuel when ford put it on their website.

http://m.ford.com/smartphone/specs.html?cid=car&mid=Mustang&year=2013#appsimHome
 

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GrabberBlue5.0 said:
The dealer needs to fire that technician. A high compression motor needs to run higher octane fuel. Yea yea, variable can timing, knock sensors, blah blah blah... Run high octane fuel. Those things are fail safe devices to prevent the motor from damage, not even sure why ford would recommend anything less than premium. Probably just to maintain a low cost of ownership.

Track pack or not doesn't matter. Still the same motor
+1 The engine designers recommend premium. Any motor that has 11:1 compression ratio needs premium fuel.
 

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Discussion Starter · #13 ·
My 93' prelude I once had ran 10:1 compression and it said right under the fuel gauge premium fuel only. Now obviously these motors have come a long way since 93' and even a high compression motor can run on 87 with no problem, but I am just amazed that Ford dealerships have techs working for them that don't know their ass from their face about the very cars their dealership is selling. Btw the guy I talked to wasn't just a tech he was the shop foreman, I know I won't be taking my car there lol.
 

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The Blue Dragon
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You always want to run as little octane as the car will allow you to run. Less octane = more energy. More octane allows the fuel to burn slower and cooler which allows you to push the car to it's limits and minimize the risk of detonation. The factory detune's our cars so much that there is no benefit to running a high octane fuel until you tune the car for a higher octane by advancing timing and what not.

I'm still learning about the Coyote motor but I know that many cars that are tuned to run 87 octane fuel from the factory can actually have their performance hurt by running a higher octane fuel. Many cars are designed to advance the ignition timing on start up until the knock sensor detects knock, if you run a high octane fuel the knock sensor will not detect any knock and will pull ignition timing all the way back because it assumes something is wrong and the car needs to run in a safe mode.

If you want to get the most out of your car drop a few hundred bucks on a tuner from American muscle and run a 93 octane tune.
Are you sure about that? Less octane means more energy? Not true. More octane means more energy. While a higher octane fuel requires more energy for combustion it also have a significantly higher energy output.

You are correct about vehicles not gaining by using higher octane fuel than they are rated for, but at 11:1 CR the coyote motor is definitely in need of high octane fuel and more advanced timing for proper AND efficient operation.

And what are you talking about with the knock sensors? You are completely backwards on that. If the knock sensors do not detect knock they will NOT pull timing.

Not sure where you're getting your info but you need to correct it
 

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Are you sure about that? Less octane means more energy? Not true. More octane means more energy. While a higher octane fuel requires more energy for combustion it also have a significantly higher energy output.

You are correct about vehicles not gaining by using higher octane fuel than they are rated for, but at 11:1 CR the coyote motor is definitely in need of high octane fuel and more advanced timing for proper AND efficient operation.

And what are you talking about with the knock sensors? You are completely backwards on that. If the knock sensors do not detect knock they will NOT pull timing.

Not sure where you're getting your info but you need to correct it
+1 ^^^^^
 

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Are you sure about that? Less octane means more energy? Not true. More octane means more energy. While a higher octane fuel requires more energy for combustion it also have a significantly higher energy output.

You are correct about vehicles not gaining by using higher octane fuel than they are rated for, but at 11:1 CR the coyote motor is definitely in need of high octane fuel and more advanced timing for proper AND efficient operation.

And what are you talking about with the knock sensors? You are completely backwards on that. If the knock sensors do not detect knock they will NOT pull timing.

Not sure where you're getting your info but you need to correct it
I'm sure about that. More octane does not = more energy. More octane requires more energy to burn. Diesel fuel has an octane rating of approx. 20.

Our cars are tuned from the factory to run 87 octane. Page 152 of the owners manual specifically states the car is designed to run 87 octane fuel, it also states premium fuel is recommended for heavy usage ie towing.

Regarding the knock sensor issue. Some vehicles do in fact have major issues with high octane fuel for the reason I mentioned before. I had a Chevy Blazer w/ the 4.3 and the dealer was extremely adamant in pointing out that I should never run anything more than 87 octane, he said they were seeing several cars come in for service and the only thing wrong with them was their owners were running higher octane fuel. On start up the cars ECU will advance timing until it sees slight detonation, once it sees the detonation it will pull timing back slightly and sets that number as the base number for ignition timing. premium fuel the ECU would often not see detonation and put it into a limp mode which essentially made it a gutless POS. I also have a boat and was told exactly the same thing about my boat as I was told about the Blazer. I'm not saying this is the case with our cars, I'm just pointing out experiences in the past where more octane has actually been bad for performance. I did additional research last night on this very subject and it does not appear to be the case with our cars.

I have regular access to a chassis dyno so I may do a comparison test in the future with the cars stock tune on 87 vs. Premium and see if there's a difference. I am willing to bet money that the difference will be extremely small if any due to the car having a very conservative tune from the factory.
 

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I believe it states that they recommend premium HOWEVER you can use 87. Which is what the dealer put in it when they filled it up, bastards.
 

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Just gonna throw this out there on the discussion table as well. The v6 owners 11-13 say that premium is a waste. Same kind of motor, just smaller. So why is it a waste in the v6 and not the GT? We share 60% of the same equipment.

Btw ford says 12 extra hp with premium over regular octane gas on the GT model. It says so in my 2012 mustang packages book I got when I bought the car.
 

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The Blue Dragon
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I'm sure about that. More octane does not = more energy. More octane requires more energy to burn. Diesel fuel has an octane rating of approx. 20.

Our cars are tuned from the factory to run 87 octane. Page 152 of the owners manual specifically states the car is designed to run 87 octane fuel, it also states premium fuel is recommended for heavy usage ie towing.

Regarding the knock sensor issue. Some vehicles do in fact have major issues with high octane fuel for the reason I mentioned before. I had a Chevy Blazer w/ the 4.3 and the dealer was extremely adamant in pointing out that I should never run anything more than 87 octane, he said they were seeing several cars come in for service and the only thing wrong with them was their owners were running higher octane fuel. On start up the cars ECU will advance timing until it sees slight detonation, once it sees the detonation it will pull timing back slightly and sets that number as the base number for ignition timing. premium fuel the ECU would often not see detonation and put it into a limp mode which essentially made it a gutless POS. I also have a boat and was told exactly the same thing about my boat as I was told about the Blazer. I'm not saying this is the case with our cars, I'm just pointing out experiences in the past where more octane has actually been bad for performance. I did additional research last night on this very subject and it does not appear to be the case with our cars.

I have regular access to a chassis dyno so I may do a comparison test in the future with the cars stock tune on 87 vs. Premium and see if there's a difference. I am willing to bet money that the difference will be extremely small if any due to the car having a very conservative tune from the factory.
I understand that the owners manual says it, but again, look at the CR of the motor and the timing tables, these motors already succumb to detonation fairly easily whether tuned or stock so why use lower octane fuel and increase the risk.

Not sure why you bring up the blazer, we are talking about the coyote motor. And I agreed with you that most vehicles will NOT benefit from higher octane fuel, so that portion of your argument holds no weight.

Also, why being up diesel motors? These are COMPLETELY different motors. Diesel engines run off compression way more so than they do combustion. The CR of any diesel motor is far far higher than the compression of any gas motor. Octane is a measure of the 8 carbon hydro carbon chains, gasoline is based off of these molecules. Diesel (I don't know the chemical make up but I know for a fact octane is far less abundant) is much thicker and has much longer hydrocarbon chains than gasoline, therefore diesel by nature has far more energy stored in it and requires far more heat and pressure than gasoline to combust

Trying to bring diesel into your argument is futile
 
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