PREMIUM-VS-REGULAR GAS FOR 2024 GT??

[GrabThatBlue]

I just found out that almost all our E5 gas stations have 0% ethanol.
The only reason why they are called E5, is that they are allowed to use a maximum of 5% ethanol in their gas, but they don't, so it's technically E0.

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[RLE55]

In this story, my freshly hand-built Spec E30 M20 engine is rated at 8.8:1 compression ratio.

100% irrelevant when discussing a Coyote engine

Ok, here's a study done by Steeda on the 5.0 coyote.....pretty much same results.
https://www.steeda.com/87-vs-93-octane-for-mustang#versus

 

[robvas]

Ok, here's a study done by Steeda on the 5.0 coyote.....pretty much same results.
https://www.steeda.com/87-vs-93-octane-for-mustang#versus

Zero data in that article

Here is an old as dirt dyno of 87 vs 91 (93?) in a gen 1

I'd like to see timing #'s and knock counts for a drive, same car on 93 vs 87

 

[Kitulu]

Here's a side question, somewhat relevant since its usually the price point of 87 vs 91 that causes us to fill up with 87...

Does running 91 do anything for the average fuel mileage, assuming that your driving habits are the same regardless of which octane you put in?

Here's a side comment to go along with the question: If you are going to chime in with something along the lines of, "you shouldn't worry about mileage in a sports car" or "get a daily driver that gets better mileage," don't. Just close the thread and move on. I don’t care if you think that, it is not relevant to the question, and will not help with the answer.

 

[AZ_Ryan]

Here's a side question, somewhat relevant since its usually the price point of 87 vs 91 that causes us to fill up with 87...

Does running 91 do anything for the average fuel mileage, assuming that your driving habits are the same regardless of which octane you put in?

Here's a side comment to go along with the question: If you are going to chime in with something along the lines of, "you shouldn't worry about mileage in a sports car" or "get a daily driver that gets better mileage," don't. Just close the thread and move on. I don’t care if you think that, it is not relevant to the question, and will not help with the answer.

Well theoretically a hotter detonation means a cleaner burn. But in today's computer controlled engines, I doubt there would be any noticeable difference in mileage.

 

[LouG]

I did the first road trip in mine when it was at 600kms I refuelled twice with 98 (93US) and once with 95 (91US). Driving reasonably gently consumption was the same at 10.7 L/100km (22mpgUS)
I haven't noticed any difference since then, apart from saving 20-30 cents per litre.
But I still use both grades.
Where I noticed a big difference was my last car, a turbo 2L. I went from 98 E10 to 98 non alcohol and fitted new Michelin PS5 tyres, which have low rolling resistance, and consumption dropped from 9.5 to 8.5 L/100kms driven quite hard ( I had some great rabbits ahead).
Both changes helped, but better than 10% less consumption? That's pretty damn good.

 

[CaesarX]

Here in Spain we can find 95 and 98... wich one should I use?

 

[GrabThatBlue]

Here in Spain we can find 95 and 98... wich one should I use?

You can use both, but 98 is better since it has less ethanol. Our 95 is the same as 91 in USA. People in USA even use 87 with no issues, which we don't even have in Europe.

 

[Bear376]

My experience is that E0 does more to improve gas mileage than higher octane. Neither makes enough difference to counter the cost. It also varies greatly with vehicles. My Dad would swear that E0 made a huge difference in his gas mileage with his old Chevy truck. While I don’t like the use of ethanol in fuel, I use it because it is cheaper.

 

[Kevi]

Ethanol gives more power but less mileage. That's why all the racers tune for e85 and why alcohol drag cars exist.

 

[Cipis]

Here's a side question, somewhat relevant since its usually the price point of 87 vs 91 that causes us to fill up with 87...

Does running 91 do anything for the average fuel mileage, assuming that your driving habits are the same regardless of which octane you put in?

Here's a side comment to go along with the question: If you are going to chime in with something along the lines of, "you shouldn't worry about mileage in a sports car" or "get a daily driver that gets better mileage," don't. Just close the thread and move on. I don’t care if you think that, it is not relevant to the question, and will not help with the answer.

From my own experience and not regarding the coyote but let’s say general petrol and petrol turbo engines I can say you can feel more smoothness with higher octane fuel and less % of ethanol. Smoothness and power seems to go along the higher the octane. Also I am doing thousands k of km on each car recording each fuel ups to full so have perfect and 100% accurate sample from past cars. I have noticed higher octane fuel makes higher milage for sure if you drive economically and it is your at least few full tanks of that premium fuel. I could make up to aprox 10-15% more km per tank on long trip. Gas pedal responds often with less effort of push and the car literally flies. On the other hand the more you start pushing the engine with high octane fuel, seems like it starts disappearing from tank faster than low octane. You feel the difference overal - the engines runs somehow quieter. Just my observation with fuels, that is why I never go below 98 RON even if I have to look for petrol station off the route.

 

[robvas]

Ethanol gives more power but less mileage. That's why all the racers tune for e85 and why alcohol drag cars exist.

Technically it has less power per amount of fuel (which is why it gives less mileage) but it allows more timing, so it can make more power

but on a engine with low compression and not much timing it won't make anymore power

 

[SpeedLu]

Nothing but Premium for the god's chariot. Regular Unleaded is for econo shitboxes with no power.

 

[robvas]

Peasant fuel

 

[LouG]

Ethanol works much like the water/methanol injection I built for my supercharged MX5. As I understand it, alcohol has much greater latent heat of evaproration than petrol, so it has a much greater cooling effect in the intake system downstream of the injector and in the combustion chamber. Because it is less energy dense than petrol it doesn't give more power, but does allow more timing advance which does.
I believe none of this happens with E10 which is a cheap and nasty way to get higher octane ratings at the cost of slightly higher fuel consumption.

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