There are many performance cars sold today that come from the factory recomendeding premium fuel or premium fuel only so why would a performance car like my 2013 GT be set up from the factory to run just fine on 87 octane fuel when we all know that Ford could have made more power if tuned from the factory to run on 91 or 93 octane. Ford seems to enjoy squeezeing a few more HP every other year out of the 5.0 so you would think that bumping up power to run on premium fuel would be a good start? .. Opinions?

 

You may be answering your own question: I believe the 5.0 coyote (or some variant) will be the standard v8 motor for many years to come... When they are in the dark years in between big refreshes and updates they might just tune it for higher octane and bump up the figures. All a bunch of smoke but could be...

Another theory is that it makes the car that much more attainable for many that aren't going to take the car to its limits to where they would be able to tell the few hp difference (most people can't anyway). It's already daunting for many to sacrifice mpgs for fun factor... I know it was for me come from the 4 cylinder world... And making premium a requirement just adds to that... Going from 30 mpgs to 20 is already a hit... Then add premium? I think it just makes the car that much more approachable for the new car buyer since it drops the cost of ownership on an already high cost of ownership car (in many people's eyes...)

 

I agree with the OP but I'm sure there are many people who would want to buy a 5.0 and be able to run it on 87. My guess (and this is just my opinion) would be that ford didn't want to limit their market to just us die hard fans. With a tune from Ford racing (and other after market vendors) easily obtainable I think this is a a good decision on their part. People who want the fun of a 5.0 on 87 can do that and those of us who want more can do that very easily.

I got the trackey on my 14 GT/CS and love having it both ways, although I have hardly used the stock key since I had it installed.

My opinion

 

I believe its to keep the yearly cost of driving down. Like extended oil life and or oil change light. Plus I think they like to leave the tuners a little play room.

 

Since the release of 08 Bullitt with "Adaptive spark ignition", your ECU adjusts timing and fuel for 87 to 93. I run 87 most of the time. When I know I want to have some fun I put in 91 (93 isn't available on the West Coast). This is the main reason I don't get a tune. I live at 4000', might be at Crater Lake at 7000', then drop down to the valley at 1500', or a few hours over to the Coast. I want that "adaptive" feature.

On the 4.6 version, it is tuned for 87 and adjusts for 91, adding mid range torque.

The 5.0 is the reverse. It is tuned for 91 and adjusts for 87. Check out your owners manual, or search threads.

 

It's a smart way to design your powertrain. The engine ecu adapts to the fuel you use. The 13-14 5.0 makes 420 on 91 octane, and 412 on 87.

I run 87 octane almost every day unless I'm at the track. Save a few $ every time I pump gas. Then when I head to the track I run 93, and get the full power the 5.0 has to offer.

 

This is interesting, I have never heard of this before. I looked at my owners manual for my 2014 and it gives no such reference. The closest thing it says is;

• 5.0L V8 engine
Regular unleaded gasoline with a pump (R+M)/2 octane rating of 87 is
recommended. Some stations offer fuels posted as “Regular” with an
octane rating below 87, particularly in high altitude areas. Fuels with
octane levels below 87 are not recommended. Do not use fuels with
octane posted on pump below 87.

Premium fuel will provide improved performance and is recommended
for severe duty usage, such as trailer tow.

 

It's been shown that running 93 will give you a decent bump in horsepower...

The car is already able to run 93 without issue, and you get all the benefits of a car that would only be able to run 93. The on board computer can adjust parameters based on the fuel used, which is why you can run anything from 87 to 93.

There really isn't a downside to the current setup. I'm not convinced Ford would have made any more horsepower by keeping it to 93 only...and any gains would have probably been small anyways.

 

keep in mind that you can not get higher then 88 oct in some area. If the car couldn't run on lower grades people wouldn't be able to buy the mustang in some areas.

 

The cars are designed to increase timing when premium fuel is used. The engine will advance timing up until detonation. Higher octane fuel allows more timing advance before detonation occurs.

 

When the price of gas is $3.25.9 for 87, and $3.75.9 for 93, (which is was around here about 3 months ago) that's $6.50 per 13 gallon fill up. (13 x $.50)

Do that 52 times a year (one per week), if you're lucky, and it's $338 per year extra to run the 93.

Not saying the big difference happens all year 'round, but... it adds up. And I don't get that lucky with my driving, it's more that 52 times a year.

That would be why they make them able to run on either octane, OP. It's just a bit more flexible for monetary reasons, and it has happened where one or the other isn't available at the pumps, so...

Although, true, "if you were worried about gas... why are you driving a Mustang, and even worse, a GT?" is a thought that comes to mind..

/I really need to figure out how to use my motorcycle more...

 

Same here. I get slightly better mileage on 87. For track days. 93

 

You can use regular gas in a GT?

 

yes.

 

Someone correct me if I'm wrong here but I thought I heard somewhere that just putting high octane fuel in the tank will NOT automatically cause the CPU to advance the Timing (on newer GT Coyote engines).
To have the CPU automatically advance the Timing I believe you not only have to put 91+ Octane in the tank, but ALSO have to drive the car a bit harder for a period of time (ie. constantly shift at higher RPMs for xx miles).
The way I basically understood it is the GT's CPU will eventually recognize the higher Octane fuel AND the consistant higher RPM's, then slowly adjust/advance the Timing to compensate for both.

If you put 91+ octane in the tank but still always drive/shift very conservatively, I don't believe the CPU will advance the timing much (if at all)...

 

I think you are confusing how the ECU adjusts to your driving style over time, with the adaptive spark ignition which adjusts to octane.

The adjustment to octane is done with knock sensors on each cylinder bank (in the valley). The ECU is designed to provide timing and A/F for peak performance within certain parameters, but if it senses knock from lower octane fuel, it pulls timing and adjusts A/F for slightly lower performance.

The best way to do it for a "play day", is to run your tank low on 87, fill with 91/93, pull the battery cables to clear the memory (I believe there is a fuse that can be pulled also), reset the idle learn, recalibrate the fly-by-wire throttle.

Of course it is not a huge increase in HP or TQ, so if you only drive conservatively, you aren't going to feel the juice anyway. That's why for driving M-F stuck in traffic, it is really just a waste of money to buy 91/93. Might as well burn dollars IMO. 91/93 is for when you want to "stretch its legs".

 

I run the 93 octane premium in my '12 GT here in NJ. I have used regular, but definitely notice a difference. Particularly in higher gears where the engine feels more lethargic. The price difference is about $.30/gal here in NJ. I figure I spent all this money for a high performance engine, I might as well get the maximum performance out of it. $3.60 a fill up is worth it to me.

 

^^ I agree and only use premium (92 is the highest I can find here in Oregon).