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would any good come out using premium 93 or 91 octane gas in a stock 2014+ kia forte koup or forte5 sx ? and would there be any negative effects from using premium gas ?
 

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Using higher octane fuel will never have a negative effect on performance, after the ecu adapts to the higher octane you would actually have increased power. Nothing but 93 octane since the first tank in my car.
 

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All higher octane does is resist pinging from higher compression. Higher octane fuel in and of itself will not increase performance unless you weren't using a high enough octane fuel to begin with.

That being said. A higher octane for these cars won't increase performance, on its own, unless the ecu does compensate and advance timing, or increase boost. I don't know enough about our ecu to say whether it does either to a significant degree or at all. But I was under the impression it didnt

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Hi. Sorry, new here, kinda. I lurke. Anyway, please do not put high octane fuel in your turbo. In order to make this decision you have to understand the difference in octane levels right? So let me give you the brief. 89-91-93 no matter what the octane is, you are getting the same gas. Well you are kinda getting the same gas. The difference lies in the additives that is given to the gas which changes the octane level. So you are saying, ok Russel, so these additives give me more go power right? Wrong! The additives just change the temperature at which the gas will burn. So, higher octane burns faster which is why I need it in my car right? Wrong! Higher octane fuel was created so that cars can run at a higher compression rate and while under boost (creates higher compression). In order to do this they had to decrease the temperature at which the fuel burns to prevent pre-ignition. So I know what you are saying, Russel, we get crazy amounts of boost, we NEED higher octane fuel. Once again, wrong, at least partly. We do have crazy amounts of boost. I have checked mine in at 26 or 28psi. It's redonk! How we get that though is why we don't need higher octane. Our cars use direct injection which puts the fuel right where it needs to be right when it needs to be there. Not before, and not after. Can you put higher octane fuel in your car? Absolutely! Will you get better performance? You might end up losing some performance. Until higher octane fuel becomes cheaper than the good ole 89 or 87 (depending on where you are), you won't catch me putting it in my car!

With all of that said, if it came out rude, my deepest apologies. Playwithmymind, I understand that the ecu will adapt to the conditions, but with direct injection, you won't see an increase in performance.
 

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Exactly. The only way to get more power (other than things such as lower the charge air temp, and advance timing) is more fuel.

To get more fuel in the same space, you need more pressure (that's where forced induction comes in). But you can only put so much pressure before heat causes the fuel to pre ignite (before the spark plug fires). This is bad. To fix this to a degree, most cars retard timing.

This creates kind of a knock histerosis (my word). It usually takes more timing retard to fix the knocking than it would have to prevent it to begin with.

Anyways. I digress. Higher octane fuel resists this preignition so that you can run higher pressures, giving more fuel, giving more power.

For example. My car ticks along around 19 psi, give or take, on 87 octane. My old 3000gt vr-4 with 17g phantoms couldn't push much past 16 psi on 93 octane without the knocking getting drastically out of hand. Different cars, different tech.

But, going along the same lines, putting vp-118 racing fuel in my vr4 didn't change anything at all, till I upped the boost. That's when the power settled somewhere on the exciting side of 700.

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Russel;8929We do have crazy amounts of boost. I have checked mine in at 26 or 28psi. It's redonk![/QUOTE said:
I would really like [email protected] to chime in on this. Have a 9.5 to 1 compression ratio running 18 lb of boost stock being GDI yes can get away with 87 but you will have a higher chance of your engine turning into a grenade if you understand these engines are prone to LSPI. If you are running 26-28 lb on this 1.6L engine what method are you using to control boost? and what was done to the bottom end to help hold it together?
 

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A higher octane for these cars won't increase performance, on its own, unless the ecu does compensate and advance timing, or increase boost. I don't know enough about our ecu to say whether it does either to a significant degree or at all. But I was under the impression it didnt
Yes these are adaptive ECUs and yes they do have limits but running 87 will have its adaptive learning have the timing reduced. Reset the adaptives and give it a fresh tank of 93 and watch the timing increase 3-4° at WOT. I have logged every sensor for every mile I have driven on this car and have seen timing differences with 93 from one gas station to the next. Anyone that thinks 4° of timing @ 18lb of boost on 93 has the same power output as 0° of timing @ 18lb of boost needs to go back to basics and start over.
 
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Hi. Sorry, new here, kinda. I lurke. Anyway, please do not put high octane fuel in your turbo. In order to make this decision you have to understand the difference in octane levels right? So let me give you the brief. 89-91-93 no matter what the octane is, you are getting the same gas. Well you are kinda getting the same gas. The difference lies in the additives that is given to the gas which changes the octane level. So you are saying, ok Russel, so these additives give me more go power right? Wrong! The additives just change the temperature at which the gas will burn. So, higher octane burns faster which is why I need it in my car right? Wrong! Higher octane fuel was created so that cars can run at a higher compression rate and while under boost (creates higher compression). In order to do this they had to decrease the temperature at which the fuel burns to prevent pre-ignition. So I know what you are saying, Russel, we get crazy amounts of boost, we NEED higher octane fuel. Once again, wrong, at least partly. We do have crazy amounts of boost. I have checked mine in at 26 or 28psi. It's redonk! How we get that though is why we don't need higher octane. Our cars use direct injection which puts the fuel right where it needs to be right when it needs to be there. Not before, and not after. Can you put higher octane fuel in your car? Absolutely! Will you get better performance? You might end up losing some performance. Until higher octane fuel becomes cheaper than the good ole 89 or 87 (depending on where you are), you won't catch me putting it in my car!

With all of that said, if it came out rude, my deepest apologies. Playwithmymind, I understand that the ecu will adapt to the conditions, but with direct injection, you won't see an increase in performance.
If you are on a stock tune the 28 psi you are seeing is probably absolute which would include the one atmosphere we all breathe
 

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I would really like [email protected] to chime in on this. Have a 9.5 to 1 compression ratio running 18 lb of boost stock being GDI yes can get away with 87 but you will have a higher chance of your engine turning into a grenade if you understand these engines are prone to LSPI. If you are running 26-28 lb on this 1.6L engine what method are you using to control boost? and what was done to the bottom end to help hold it together?
I would always recommend premium with any turbocharged car. Yes the factory say you can run lower octane but they just design the ecu to be able to pull power out when it inevitably knocks for poor quality fuel. As for the boost part of it I quoted his post
 

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Yes these are adaptive ECUs and yes they do have limits but running 87 will have its adaptive learning have the timing reduced. Reset the adaptives and give it a fresh tank of 93 and watch the timing increase 3-4° at WOT. I have logged every sensor for every mile I have driven on this car and have seen timing differences with 93 from one gas station to the next. Anyone that thinks 4° of timing @ 18lb of boost on 93 has the same power output as 0° of timing @ 18lb of boost needs to go back to basics and start over.
No I agree. If it does change the timing that far then that's usually not only enough to show, but to feel. 4 degrees advance on my 3000 was good for 14 whp, at all 4 wheels.

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I was just under the assumption (yes I know) that to be idiot proof, it had a limit of advance that never went past the safety of 87 octane, even with 93 in the tank. So that if you went from 93 to 87, nothing was advanced anyways, so no harm done

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I hand cast my block in my garage with a 60/30/10 mix of aluminum, carbon fiber, and unobtainium. Lol just kidding. I misspoke earlier. It is 16-18lbs. That being said, my earlier comments were based on higher octane fuel being a performance gain all by itself. I was unaware though that our ECUs could adjust timing that much. That is pretty awesome and I would love to see the numbers you are getting. You might just convince me to fill up with 98. :)

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I hand cast my block in my garage with a 60/30/10 mix of aluminum, carbon fiber, and unobtainium. Lol just kidding. I misspoke earlier. It is 16-18lbs. That being said, my earlier comments were based on higher octane fuel being a performance gain all by itself. I was unaware though that our ECUs could adjust timing that much. That is pretty awesome and I would love to see the numbers you are getting. You might just convince me to fill up with 98. :)
With just a FMIC the car gained 22 WHP (166 stock with auto trans). 3" ss dp and full 3" ss exhaust, FMIC and SRI for 209 WHP 219 WTQ on a stock ecu. Running 87 at WOT and 18lb of boost, one might see 4.5° maybe 6° advanced timing on quality 87, I am consistent between 9 and 11° on 93. For me and most who race and have history in different areas of motorsports 4-5° of timing at WOT and 5000+ rpms is a huge bonus. Might not be that noticeable all by itself but could be the little extra needed to break past the 14.5 sec mark or get that little extra the guy beside you doesn't have.
 
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Yes indeed. If it advances timing for 93, where is the limit? I can get 100 from a Chevron up the road...

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With just a FMIC the car gained 22 WHP (166 stock with auto trans). 3" ss dp and full 3" ss exhaust, FMIC and SRI for 209 WHP 219 WTQ on a stock ecu. Running 87 at WOT and 18lb of boost, one might see 4.5° maybe 6° advanced timing on quality 87, I am consistent between 9 and 11° on 93. For me and most who race and have history in different areas of motorsports 4-5° of timing at WOT and 5000+ rpms is a huge bonus. Might not be that noticeable all by itself but could be the little extra needed to break past the 14.5 sec mark or get that little extra the guy beside you doesn't have.
Sounds like a FMIC is an excellent first mod!

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Yes indeed. If it advances timing for 93, where is the limit? I can get 100 from a Chevron up the road...
lol well I would build the bottom end and upgrade the turbo to push 30lb of boost before going that high.

Also remember air temp plays a huge role in this also, if it is a constant 60° F and your AITs never got high you will be less likely to have issues with 87. If you live in the southern hotter climates where it is 110° F and IAT is 170° F 93 just might be your friend lol
 

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87 octane cause stuttering on hot days here. The humidity is so much so that some days I almost have to take my boat to work. The stuttering alone has made me switch to 93.

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87 octane cause stuttering on hot days here. The humidity is so much so that some days I almost have to take my boat to work. The stuttering alone has made me switch to 93.
Sounds like Florida lol

Sounds like a FMIC is an excellent first mod!
No catch can first lol, really depends on how far you want to go with modding
 

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Hi. Sorry, new here, kinda. I lurke. Anyway, please do not put high octane fuel in your turbo. In order to make this decision you have to understand the difference in octane levels right? So let me give you the brief. 89-91-93 no matter what the octane is, you are getting the same gas. Well you are kinda getting the same gas. The difference lies in the additives that is given to the gas which changes the octane level. So you are saying, ok Russel, so these additives give me more go power right? Wrong! The additives just change the temperature at which the gas will burn. So, higher octane burns faster which is why I need it in my car right? Wrong! Higher octane fuel was created so that cars can run at a higher compression rate and while under boost (creates higher compression). In order to do this they had to decrease the temperature at which the fuel burns to prevent pre-ignition. So I know what you are saying, Russel, we get crazy amounts of boost, we NEED higher octane fuel. Once again, wrong, at least partly. We do have crazy amounts of boost. I have checked mine in at 26 or 28psi. It's redonk! How we get that though is why we don't need higher octane. Our cars use direct injection which puts the fuel right where it needs to be right when it needs to be there. Not before, and not after. Can you put higher octane fuel in your car? Absolutely! Will you get better performance? You might end up losing some performance. Until higher octane fuel becomes cheaper than the good ole 89 or 87 (depending on where you are), you won't catch me putting it in my car!

With all of that said, if it came out rude, my deepest apologies. Playwithmymind, I understand that the ecu will adapt to the conditions, but with direct injection, you won't see an increase in performance.
I think this needs clarification.

Octane is a measure of the gas resistance to what is called knocking, pinging or detonation. These words are short for PRE-IGNITION.

Pre-ignition is when the air/fuel mixture ignites before the spark plug fires. When you compress the air and gas, you can reach the compression threshold of the gasoline before the spark plug fires if the octane is too low for the conditions.
What conditions? Anything that raises pressure and/or temperature, like forced induction.

There are much stronger forces present in a pre-ignition event, and this is what damages engine internals over time. It also produces higher combustion temperatures, which is also damaging.

You will never catch me putting in less than 93 octane fuel unless it's not available. The engine in stock form may be ok for light/normal driving out of boost on 87 octane gas, and the luckily for you the ECU is smart enough to detect knocking and retard the timing because the octane level isn't high enough when you boost the engine and go wide open throttle.

If you ever do any spirited driving or plan to increase the power level of the engine, please only use 93 octane or higher. Anything else is just dancing with the devil.
 
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