2018 GT MPG 87 vs. 93 octane

[bootlegger]

What rear end gears do you have? 3.73's? I personally don't have any problems going up a mountain but I also have 4.10's. Someone with 3.31's won't be so lucky without going really fast. Especially since 6th is an overdrive gear.

PP is 3.73. Even with 3.31, I don't see it being an issue unless it is a really steep grade (for 18+).

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[WildHorse]

 

[WildHorse]

Anyways here's my smiles per gallon with 93 octane ( @ 63 mph cause the speed limit is 60 mph )
FLat road well because Manitoba

 

[Dfeeds]

Anyways here's my smiles per gallon with 93 octane ( @ 63 mph cause the speed limit is 60 mph )
FLat road well because Manitoba

Is your gas pedal busted?

 

[WildHorse]

Is your gas pedal busted?

The RCMP are pricks around here.. they'll pull you over if there radar show 1mph over the speed limit. I shit you not.
And just for the record, it's around the same @ 70 mph.

 

[Mustang5ohMan]

I don’t know coming from my Scat Packs which required premium it seems like you can go any route with this Mustang.
87/89/93....
I mean I live in Florida where it gets hot but i don’t know may run 87 and save the money it says you can in the manual so it hopefully it isn’t an issue.

 

[GregP27]

As an engineer and part-time thermodynamicist, I'd say you need to back off on what can be predicted by compression ratio. The guys who spend MILLIONS of dollars racing say otherwise, at least to me. Admittedly, I'm talking with guys who race airplanes, but these guys and my own experience tell me almost anything over about 10.5 : 1 should be running higher grade fuel, either octance or performance number. As you know, anything over 100 is a performance number, not an Octane rating. They run grade 150 in racing aircraft at Reno. When I was turbocharging sandrails in Arizona (two Subaru turbos on a big VW block), we'd put a regulator in-line with the turbo wastegate that was usually factory-set to 6.0 - 6.5 psi. Then we'd crank down on the regulator to get more boost.

Reguar fuel would detonate rather quickly, then we'd switch to higher octane and get a bit more boost, usually about 2 - 4 more psi before it detonated again. Then, we'd rejet and switch to methanol and get maybe 4 - 8 more psi. Might have gotten more, I don't know because too many guys kept cranking up the boost. It ran better and better right up until it blew up in a scrap iron fit. I stopped at about 280 hp and was happy with the results.

Later, I switched to a Mazda rotary (bridgeported 13B) and was also very happy with it, especially since we could find them almost free in old RX-2's and such sitting around. EASY to work on and get some HP from. We'd get the eccentric shaft pinned and take the bridgeported engines to 10,500 rpm with no issues and 225 - 240 HP and VERY light weight. More with a turbo.

I don't want to start anything, but my engine opinions are taken from hot rodding since the mid-1960's with big and small blocks, natural atmospheric and boosted, as well as Wankels and big WWII V-12s (1649 and 1710 cubic inch V-12's and radial as large as 3,350 cubic inches).

So, you may be correct.

I'll stick with what I KNOW to be true from personal experience, not some magazine. I'm not not that your opinions are from magazines ... not saying that. All it means to the two of us is I run gas that is slightly more expensive than the gas you run, and I do it at my own option. No big deal to either of us. I'd love to get together some time, but California is a LONG way from North Carolina! it's all good as long as we don't blow 'em up or wreck 'em. I'll do my part as well as I can. Hope you do, too.

Cheers to you, Ebm, no sarcasm intended.

 

[Armageddon Turbo]

I run premium all the time.

 

[WildHorse]

87 octane is for one thing: Sales. You're more apt to buy a performance car knowing you can put the cheapest possible gas into it. WHy people put the cheapest things into high performance cars is beyond me. Like oil too. they put the cheapest oil they can get, and if you think the quality of that oil will still be there even halfway before the computer says to change it, your delusional. Or why put dot 4 brake fluid when dot 3 is half the price. Or put in cheap walmart ATF when it's the third of the cost of Mercon ATF etc., etc.

 

[OldPhart]

I run premium all the time.

Hi - Premium gas for my car and premium beer for me... Bruce

 

[Bikeman315]

87 octane is for one thing: Sales. You're more apt to buy a performance car knowing you can put the cheapest possible gas into it. WHy people put the cheapest things into high performance cars is beyond me. Like oil too. they put the cheapest oil they can get, and if you think the quality of that oil will still be there even halfway before the computer says to change it, your delusional. Or why put dot 4 brake fluid when dot 3 is half the price. Or put in cheap walmart ATF when it's the third of the cost of Mercon ATF etc., etc.

If you put in fluids that do not meet manufacturers specifications it can void your warranty for a parts related issue. Using 87 gas will not do this. It certainly will not help the engine performance but it will not hurt it either. So long as Top Tier gas is used no one should be concerned about 87 harming their car. It's a personal choice. I chose to use 93 but that's just me.

 

[Bikeman315]

I don’t know coming from my Scat Packs which required premium it seems like you can go any route with this Mustang.
87/89/93....
I mean I live in Florida where it gets hot but i don’t know may run 87 and save the money it says you can in the manual so it hopefully it isn’t an issue.

Running in the Florida heat in the summer months could constitute "severe" conditions. Let your ears and your butt guide you. If you hear knock or feel the car is sluggish throw in a few tanks of 91/93.

 

[WildHorse]

fluids that do not meet manufacturers specifications

almost all the cheap stuff meets manufactures specs. How long the hold those properties is another matter altogether,

 

[RacinJason]

Tuned or not? I run premium all the time, and since the day I bought the car. 93 is what we have around here. 87, 89, or 93 is all you can get. No E85 or whatever else there may be. Stock on premium I ran 18.2 to 18.3 MPG City mix driving, and driving how I drive. I tuned, same 93 fuel, and I've gotten better gas mileage. 20 and over, driving the same... No tuner would knock the tune either. The tunes are worth your time. More power and better gas mileage?

 

[GregP27]

Bikeman 315, I think you are wrong. Today's engines advance the timing until they detect detonation and back it off slightly until no more detonation is detected. When they do that (think Digital Fuel Injection and the attendant sensors), then the 87 octane fuel WILL result in less power delivered before detonation is encountered ... IF YOU ARE USING THAT MUCH POWER from your engine.

If you are not, then 87 octane is OK. But if you are making more than around half of the max power output of which the engine is capable, higher octane fuel will result in more power produced and delivered before detonation starts to occur. In this case, the lower octane fuel will be constrained to not detonate by the CPU, but it WILL hurt your possible power produced relative to using better-performing fuel. The CPU may not allow the engine to be damaged, but it will also make less power then it would with better fuel.

A carbureted engine will not run that way, adjusting for detonation. But digital fuel injection will.

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