Octane for '15 5.0

[Arabian Mustang]

How's the gas prices there in Dubai? I've heard it's crazy cheap.

compared to US yes its dirt cheap , compared to Middle east we have the highest prices almost double as other countries like Saudia Arabia , Oman Etc

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[Swoope]

compared to US yes its dirt cheap , compared to Middle east we have the highest prices almost double as other countries like Saudia Arabia , Oman Etc

wondering how this is working out for you?

2014 Audi S5 coupe, 7speed, Giac stage2+, AWE pulley kit, Giac dsg tune

have an rx8 track car and a 12 gti. have been looking at the mustang and the golf r.

beers

 

[Wizzard77]

Is 11:1 really high compression?

I would never put 87 octane in a performance engine with high compression that makes more power on higher octane, because all I'd be doing is robbing power and decreasing fuel economy.
.

Since when is 11:1 a high compression engine? That's borderline to call it high compression, upwards of 11.5:1 or starts to require high octane to prevent knock, 11:1 does not with variable valve & all the other bells & whistles. With a 1% power loss due to 87 instead of 93, I'll be running 87 octane all 100,000 miles that I'll put on the car in the next 3 years.

Also, what do you define as fuel economy? Is it the price you pay per mile, or the mpg number you see in the cluster? In my area premium is about $0.20 more than 87 regular, or about 6% more. MPG improvement of 93 octane versus 87 octane is about 1% or less. So, pay 6% more money for 1% improvement in mileage is a net loss if you are looking a price per mile. (Simple terms: You pay more money per mile if you use high octane fuel.)

Now since you're paying upward of $40k for a vehicle, yes you can probably afford premium gas. If it makes you feel better to do so, then do it, but there's no necessity on a stock engine to run high octane unless you're at the drag strip where 1% power difference may help. Now, when you put your aftermarket tunes in, by all means do what they tell you to do since you're throwing away the thousands of hours the Ford engineers put into testing and evaluating the engine performance to get it to last 100,000 miles on 87 octane.

Now what I hate is the 10% ethanol mandate in many states, except in Iowa that grows all the damn corn used to make ethanol, they get the option of "normal" fuel without ethanol, it's even CHEAPER. What! Their economy is boosted by the rest of us using their corn and yet they don't have to buy it. That's crazy right there. I will buy non-ethanol fuel any time I can get it, generally see 3 to 5% improvement in fuel mileage without ethanol, but it's hard to know for sure without a controlled test.

 

[Wizzard77]

R Remember that changing octane requires the ECU to learn the change...by running into knock and then backing out timing.

This is not true. The car will always, repeatedly, many times per second, lean until knock and then enrich the fuel ratio. Constantly, repeatedly, regardless of if there's 93 or 87 octane in the tank. There's no "learning curve" for the ECU. There are so many factors affecting knock such as engine temperature, ambient air temperature, fuel octane, etc. that the ECU is always adjusting the spark and valve timing, fuel ratio, and many other parameters to make just enough power.

 

[Swoope]

This is not true. The car will always, repeatedly, many times per second, lean until knock and then enrich the fuel ratio. Constantly, repeatedly, regardless of if there's 93 or 87 octane in the tank. There's no "learning curve" for the ECU. There are so many factors affecting knock such as engine temperature, ambient air temperature, fuel octane, etc. that the ECU is always adjusting the spark and valve timing, fuel ratio, and many other parameters to make just enough power.

well there is this thing called long term fuel trim, but i want to know where 87 to 93 is 20 cents.

in fla right now it is 20 from 87 to 91 then 20 to 93.

beers

 

[Arabian Mustang]

wondering how this is working out for you?

2014 Audi S5 coupe, 7speed, Giac stage2+, AWE pulley kit, Giac dsg tune

have an rx8 track car and a 12 gti. have been looking at the mustang and the golf r.

beers

To be honest the audi was my biggest mistake, I grew up as an American muscles fan, dont know why i ended up buy an Audi spending around 6000k usd of mods and parts on it and a 5.0 mustang with few bolts on will rape me anywhere anytime! Very expensive to mod German cars, but the only advantage they got is the DTC, PDK, DSG etc and AWD, from a dig with lunch control I'll be able to have fun with a GT500 2013 as soon as his tires stick to the road! Bye bye!! My advice is stick with the mustang you'll never be wrong with it!!

 

[Wizzard77]

well there is this thing called long term fuel trim, but i want to know where 87 to 93 is 20 cents.

in fla right now it is 20 from 87 to 91 then 20 to 93.

beers

GasBuddy.com, but yes, no 93 octane currently in Detroit Metro area until next summer. 87 to 91 today is $0.22 more in Sept-14. But I do see on GasBuddy that Florida prices are $0.45 different for 87 to 91, too bad for you guys.

And Long Term Fuel Trim (LTFT1 and/or LFTF2) is used on a cold engine at startup under open loop conditions. Short Term Fuel Trim (STFT) is what you care about when driving around on the street. I suspect some aftermarket tunes probably force LTFT1/2 into some value at WOT to run slightly rich on the assumed octane. That's why it would be necessary to use the 91 or 93 octane for specific tunes or risk significant knock.

 

[USPSALIMITED]

Hmm, Ford says a 1% power loss running 87 octane.

I will likely never notice 1%, and all things considered there should be a cost savings with 87.

Barring any problems, 87.

 

[Mikeiscoo2]

Since when is 11:1 a high compression engine? That's borderline to call it high compression, upwards of 11.5:1 or starts to require high octane to prevent knock, 11:1 does not with variable valve & all the other bells & whistles. With a 1% power loss due to 87 instead of 93, I'll be running 87 octane all 100,000 miles that I'll put on the car in the next 3 years.

Also, what do you define as fuel economy? Is it the price you pay per mile, or the mpg number you see in the cluster? In my area premium is about $0.20 more than 87 regular, or about 6% more. MPG improvement of 93 octane versus 87 octane is about 1% or less. So, pay 6% more money for 1% improvement in mileage is a net loss if you are looking a price per mile. (Simple terms: You pay more money per mile if you use high octane fuel.)

Now since you're paying upward of $40k for a vehicle, yes you can probably afford premium gas. If it makes you feel better to do so, then do it, but there's no necessity on a stock engine to run high octane unless you're at the drag strip where 1% power difference may help. Now, when you put your aftermarket tunes in, by all means do what they tell you to do since you're throwing away the thousands of hours the Ford engineers put into testing and evaluating the engine performance to get it to last 100,000 miles on 87 octane.

Now what I hate is the 10% ethanol mandate in many states, except in Iowa that grows all the damn corn used to make ethanol, they get the option of "normal" fuel without ethanol, it's even CHEAPER. What! Their economy is boosted by the rest of us using their corn and yet they don't have to buy it. That's crazy right there. I will buy non-ethanol fuel any time I can get it, generally see 3 to 5% improvement in fuel mileage without ethanol, but it's hard to know for sure without a controlled test.

If mileage is your concern for a v8 mustang.. then go change it to a v6.. in my honest opinion if you put anything other than the highest Octane fuel in a sports car, you really just shouldn't have it. You should be slapped in the face and have it taken away from you. Along with whats left of your man card. You also contradict yourself by saying you buy non-ethanol fuel any time you can get it.. but its still only a 3-5% increase in mileage.. so then youre still just wasting money anyways.

 

[RobHunt]

Put whatever you want in it, 87,89 or 91 (or higher). The motor will compensate accordingly. If you tune it, use whatever the tune needs. Don't worry about opinions, ford recommends 87 according to the manual. Just enjoy your ride and treat it well (maintenance).

I will be running mid grade because it has a little better performance and it has less ethanol.

My wife says that I can keep the man card regardless of the fuel I use. She approved the car purchase.

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[dwaleke]

I will be running mid grade because it has a little better performance and it has less ethanol.

Do you have any references to this? I've never come across docs that state higher octane at the pump uses less ethanol. If anything I'd think it would be the opposite.

Not calling you out. Just want to read up on it.

 

[RobHunt]

http://pure-gas.org also, at most of the pumps, it states may contain x% ethanol. Here it is 10% in 87, 5% in 89, etc.

Most of the time you have to get 91 or better if you want no ethanol.

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[dwaleke]

Ok thank you. Not much on that site for me unfortunately.

I'm in southeast Michigan and pretty much all the pumps regardless of octane level state max 10% ethanol. I've read that the amount hovers around 7-8%. Lower if ethanol is in higher demand.

I'm going to supercharge my car so bring on the ethanol. It I didn't have to fill up frequently I'd run an E85 tune.

 

[Swoope]

http://pure-gas.org also, at most of the pumps, it states may contain x% ethanol. Here it is 10% in 87, 5% in 89, etc.

Most of the time you have to get 91 or better if you want no ethanol.

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that must be a canada thing. most usa gas it 10% eth or less. though you can find sunoco 90 oct eth free at some stations.

beers

 

[souprmage]

I'm glad 91 is only $0.20 more than 87 here.

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