93 octane to 87

[BBB]

you bought a v8 performance car, treat it as such

premium fuel only or get a honda econobox

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[paul123]

Honestly, I'd be more concerned about power seats, windows, and other fancy electronics working 10-15 years from now. The manual says you can run 87, it'll be fine as long as you don't get a tune.

^ this

 

[Raoh]

you bought a v8 performance car, treat it as such

premium fuel only or get a honda econobox

Hey! You're still here! And I need to budget myself a bit more if I am driving twice as far to work every day, and the easiest way to do that is to drop some of the fuel cost. But, considering it will be more highway driving and less city driving, maybe the jump wont be so bad. I only get 18.1 mpg average, but highway I get something like 25.

 

[BBB]

Cost difference between 87 and 91/93 is like $0.25/gal. On a full tank of gas you'll be saving $4. That ain't shit

 

[Figures]

The manual even states that its on a 1% or roughly 5HP decrease in power, so you should be fine.

Octane really is a number that relates to "detonation" of the fuel, higher Octane has a slower detonation or has a higher resistance to burn.

Great video about tuning from Steve Dinan



Good info here to:

http://www.contactmagazine.com/Issue54/EngineBasics.html

 

[paul123]

for long distance commuting, try the 87. If you don't take an MPG hit, just keep doing that. Supposedly the Coyote pulls timing, and prevents knock, at the expense of power. If it's in the owners manual

 

[paul123]

Cost difference between 87 and 91/93 is like $0.25/gal. On a full tank of gas you'll be saving $4. That ain't shit

^ this. I forgot gas is cheap

 

[Blk2015GT]

The manual even states that its on a 5% decrease in power, so you should be fine.

Octane really is a number that relates to "detonation" of the fuel, higher Octane has a slower detonation or has a higher resistance to burn.

Great video about tuning from Steve Dinan



Good info here to:

http://www.contactmagazine.com/Issue54/EngineBasics.html

This x1000000.

Most common misconception that higher octane is "the good stuff" that's been drummed into the public's minds. Completely untrue.

Second, the car's own manual says 87 and up. Unless you're running a tune or FI on the GT you don't NEED 89, 91 or 93.

Third, as pointed out, you only lose 1% hp actually, not 5%. Do the easy math its a whopping 4.35hp at the crank, under 4hp at the wheels. (" If you fill up using 87 octane, you’ll be down on horsepower—by about one percent according to Ford" http://www.caranddriver.com/reviews/2015-ford-mustang-gt-instrumented-test-review)

It's quite a bit more on the Ecoboost b/c it's a turbo engine- about 11.3% http://www.mustang6g.com/?p=4973

I'll take gas at $2 any day over 4-4.5hp. Premium 93 here is $.50 more per gallon than 87; that's $7.50 filling up with 15 gallons. Tossing money down a hole to get 4hp basically; even if yo only fill up once per week that's $400 a year for 4hp.

 

[Raoh]

Cost difference between 87 and 91/93 is like $0.25/gal. On a full tank of gas you'll be saving $4. That ain't shit

87 and 93 had a 65 cent difference when I checked last near me. That's over 10 dollars a tank, and that adds up! If it was such a small difference, I wouldn't care lol.

 

[Raoh]

This x1000000.

Most common misconception that higher octane is "the good stuff" that's been drummed into the public's minds. Completely untrue.

Second, the car's own manual says 87 and up.

Third, as pointed out, you only lose 1% hp actually, not 5%. Do the easy math its a whopping 4.35hp at the crank, under 4hp at the wheels. (" If you fill up using 87 octane, you’ll be down on horsepower—by about one percent according to Ford" http://www.caranddriver.com/reviews/2015-ford-mustang-gt-instrumented-test-review)

It's quite a bit more on the Ecoboost b/c it's a turbo engine- about 11.3% http://www.mustang6g.com/?p=4973

I'll take gas under $2 any day over 4-4.5hp.

Man, even 87 is 2.40ish right now here. And that's super cheap. I am going to start using 87!

 

[Blk2015GT]

87 and 93 had a 65 cent difference when I checked last near me. That's over 10 dollars a tank, and that adds up! If it was such a small difference, I wouldn't care lol.

Yeh no way 87 to 93 only has a $.25 difference. Maybe 87 to 89 or 91

87 to 93 is right at $.50 everywhere around here. That's a $7.50 per fillup; not a tiny amount to get that 1% hp (4.35hp)

 

[Chameleon]

No, you will be fine going to 87.


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[Glenn G]

I would take reset the ecu by pulling the negative battery terminal for a few mins. Right now your octane adjust ratio is probably at -1 because you have been using 93 so the PCM is using the most aggressive timing map programmed in it. as it detects pinging from the lower octane fuel it should adjust itself down to +1 for 87. By resetting the ecu you will start back at 0 so the timing difference is not as huge and it won't knock as hard if you get on it.

I am assuming the OAR works the same for the V8 as it does for the ECO, I don't see why it wouldn't but :shrug:

 

[Raoh]

I would take reset the ecu by pulling the negative battery terminal for a few mins. Right now your octane adjust ratio is probably at -1 because you have been using 93 so the PCM is using the most aggressive timing map programmed in it. as it detects pinging from the lower octane fuel it should adjust itself down to +1 for 87. By resetting the ecu you will start back at 0 so the timing difference is not as huge and it won't knock as hard if you get on it.

I am assuming the OAR works the same for the V8 as it does for the ECO, I don't see why it wouldn't but :shrug:

Can I avoid any knocking by just not driving it very hard for a half a tank or so?

 

[Glenn G]

Can I avoid any knocking by just not driving it very hard for a half a tank or so?

Yeah if you are not beating on it you will be fine. In normal driving it might not even ping at all which is actually bad because you want the ECU to know it has lower quality fuel in it. You want to do some mid throttle pulls (don't rag on it) it takes my Ecoboost about 5-6 pulls to learn a new OAR. It's a pity Cobb doesn't support the V8 because that's how I monitor my fuel quality every tank.

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