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Discussion Starter #1
Hi !

Did anyone try or is regulary using premium gasoline for is 2.4L Forte Koup ? Have you seen some benefits if yes ?
It's supposed to upgrade performance, the engine preservation, the valve cleanliness and to decrease the fuel comsuption.

well, I know which difference does a 91 octane fuel, but it is better in a high compression level engine.

What do you think about that ?
 

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premium in any Forte is a waste of money. Octane serves only the purpose of preventing pre-detonation in high compression engines - which the 2.4 is not. Top Tier fuel suppliers use the same detergents in all grades of gas they sell, so a good quality 87 octane fuel is what you'll want to use in this car.

If you get a Koup Turbo, it'll likely require 91 or 93. Until then, save your money.
 

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If an engine is designed to run on 87 octane then that will give the best performance. With 91 you'll actually lose power. The only way to gain HP is to reprogram the computer to increase the timing for 91 octane, assuming the engine is stock. If an engine has a recommended octane higher than 87 (usually written on the gas cap) you'll gain performance because the computer has the ability to keep adding timing as long as it doesn't detect spark knock. Save your money and use 87.
 

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You'll lose power if you use higher octane fuel?? I can't find a station in my city that carries 87 grade. It is 89 to 93 grades.
 

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Discussion Starter #5
I already know what does octane bring in fuel, but in my first car, a 1997 toyota corolla, i used premium for a while and i was able to do about 50 miles more per tank of gas. Strange !
 

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Ohh ! Lol I worked in a Shell gas station few year ago, and here in my city it's

From shell Canada :

Shell Road Octane Numbers (Anti-Knock Indexes)
The following are minimum specifications for Shell fuels:

Shell V-Power: 91
Shell Silver: 89
Shell Bronze: 87
 

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My tank has only ever seen one time when I didn't use premium - the 5 litres they put in it in Korea to get it on the boat. Since then I have exclusively used the same gas station and always their highest octane offering. My main reason is that it is a Co-op, and I get about 11 cents on a litre back at the end of the year, so high grade fuel there is actually cheaper than any other gas in town.

I remember in school they went on and on about octane and fuels and emmissions and all the other stuff I can't ever think of, but the important thing is that if you run your car hard, use premium. If you drive it like a granny, then run whatever you want. The ECU in a Forte can and will adapt to the higher available octane if you provide it on a consistent basis, so once you start, it's in your benefit to continue. Of course, every tank of fuel is different (like pouring drinks.. some have a little more kick than others) and since you'll never run your tank dry it's always a blend in the tank, anyways.

So is premium required? No. Will you actually notice a difference in performance or fuel economy? Possibly one or the other - but never both. Will your car notice the difference? Yes.
 

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Hey Kiatech, will the ECU also adjust over time to the fuel air ratio when you use a CAI? Or always run richer fuel until you tune it?
 

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Mfury, the Fortes are MAP based EFI. A difference between MAP & MAF is MAP does not meter air like MAF;instead, it takes the readings from several sensors, then, chooses a pre programmed map. Yes, we will be running rich:) until a tune.
 

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Over here unleaded gas is 91 octane and premium is 95-97 octane then this fuel with ethenol added and thats 93 octane.
I try and use Premium 95 octane my car performs better down low and greater pulling power when taken off in higher gears. Also better economy (MPG).
I steer clear of these cheaper gas outlet places where they offer 4-8 cents off for shopper docket, they use s--t fuel and my car doesn't perform as good.
The fuel my car goes better on is Premium unleaded 95oct from Shell
 

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*sigh* the car will NOT run rich due to intake changes. You could run a car with a filter built from a wool blanket next to a car without a filter at all... the cars will adjust their fuel trims accordingly and run just fine based on the air available.

The ECU constantly monitors the air/fuel mix in the exhaust, via the upstream O2 sensor, and constantly adjusts the injector pulse width to compensate.

The entire "open intake makes your car rich" theory is funny... think about it: 'rich' means more fuel than required, which means less air... how is a less restrictive intake supposed to lower the air coming in? If anything... logic would say that you'd run lean. But thankfully fuel injection and O2 sensors (and the last 30 years of auto engineering...) have completely negated the problem and the car will compensate for nearly anything you can throw at it.
 

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*sigh* the car will NOT run rich due to intake changes. You could run a car with a filter built from a wool blanket next to a car without a filter at all... the cars will adjust their fuel trims accordingly and run just fine based on the air available.

The ECU constantly monitors the air/fuel mix in the exhaust, via the upstream O2 sensor, and constantly adjusts the injector pulse width to compensate.

The entire "open intake makes your car rich" theory is funny... think about it: 'rich' means more fuel than required, which means less air... how is a less restrictive intake supposed to lower the air coming in? If anything... logic would say that you'd run lean. But thankfully fuel injection and O2 sensors (and the last 30 years of auto engineering...) have completely negated the problem and the car will compensate for nearly anything you can throw at it.
thank you for clarifying this, very good to know. I think I and a bunch of people are probably just unsure of how exactly a MAP system works since we've probably all had mostly MAF cars in the past
 

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kiatech wrote:
*sigh* the car will NOT run rich due to intake changes. You could run a car with a filter built from a wool blanket next to a car without a filter at all... the cars will adjust their fuel trims accordingly and run just fine based on the air available.

The ECU constantly monitors the air/fuel mix in the exhaust, via the upstream O2 sensor, and constantly adjusts the injector pulse width to compensate.

The entire "open intake makes your car rich" theory is funny... think about it: 'rich' means more fuel than required, which means less air... how is a less restrictive intake supposed to lower the air coming in? If anything... logic would say that you'd run lean. But thankfully fuel injection and O2 sensors (and the last 30 years of auto engineering...) have completely negated the problem and the car will compensate for nearly anything you can throw at it.
to get the potential from youre purchase like a cai it will run rich until you get the tune.
 

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Since I drove it away from the dealer, this car has gotten only premium 93 octane gas. At first I was using Shell V-Power, since it has the motor cleaning additives, but recently switched to Texaco with Techron which also cleans the motor. So far, Texaco lasts longer than Shell.
 

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Premium gas = waste of money, though I know that some people seem to use premium for the sake of using premium. Don't kid yourself: you aren't FI, and you aren't high compression. Premium is NOT required.
 

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You'll lose power if you use higher octane fuel?? I can't find a station in my city that carries 87 grade. It is 89 to 93 grades.
Gasoline has a BTU rating of around 115,000 or so. This stays the same irregardless of the octane rating. The octane rating is a measure of a fuels resistance to auto ignite. So your running a fuel in your engine that's harder to ignite than what it was designed for. You won't get as complete a burn which results in less power and higher emmisions. As KiaTech says the ECU over time will adapt to the higher octane of the fuel and make use of it. However no manufacturer is going to allow it's ECU to come close to pushing the fuel and timing curves to just before detontation especially if the engine doesn't have a knock sensor for the simple reason of warranty issues. If your able to flash the ECU to take full advantage of the 91 or high octane then it's probably worth it but for maybe a few horsepower from the stock ECU with the fuel costing 11 cents a litre more doesn't really seem worth it IMO It's strange you don't have 87 octane there. How much does the 89 cost?
 

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Funny this forum came up cause i posted something similar on another thread but since i first purchased my koup i have been putting 87Octane, until today i decided to go with 89Octane reason why i switched was because car was just running shity. Anyhow, long story short car is running smooth as butter and also improved my mpg by 6. 6mpg. when i was running on 87 i will average 25 maybe 26 on a good day. Well today it instantly jumped to 30mpg city lots of stop and go and shit. But anyways i hope you get where am going with this. Get rid of that cheap Gas man as a matter of fat look it up in the manuals you can add up to 91 or 93 i believe. The vehicle can take it. High compression ratio is like 10:1 or something like that so yeah. The End!!
 

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93 ultra sunoco here <----- have to :p
 

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Reporting on improved MPG by use of premium fuel is flawed logic. It implies that there is more power contained in premium fuel, therefore causing the ECU to inject less of it. This is false.

Atmospheric conditions, driving habits, warm-up time, etc. contributed to your improved mileage. Octane levels in your fuel had nothing to do with it. It's merely a pre-detonation preventer, and contains no more power per gallon than 87 octane.
 

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to get the potential from youre purchase like a cai it will run rich until you get the tune.
You realize of course that the Forte comes from the factory with what is essentially a CAI? And what science or voodoo do you wish to cite to back up your claim? I have provided a very complete argument to support my side of the debate; let's see your's. I am not trying to start a war, but my intentions here are to support the forum with facts and known information. You arguing against me will require that you substantiate your claim.
 
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