Kia Forum banner
21 - 40 of 42 Posts

·
Registered
2019 Kia Sportage. SX with AWD. 2.0L Direct Injected Turbocharged & Intercooled Gas.
Joined
·
1,398 Posts
I don't know how many ways I can say this, BUT THIS IS JUST NOT TRUE FOR OUR CAR. This subject has been researched by people far more knowledgeable than you or I -- and I read much of the research. It is confusing because there are many cars where this is true. It all depends on the design of the engine and the way the ECM has been programmed. What happens is that when you put in premium, the car doesn't know that fact. So the ECM constantly tries to improve performance by pushing the limits. If you get a high performance vehicle with a large engine, then there will be a difference in the majority of cases. But in the tests I've seen for turbocharged small 4 cylinder vehicles, there has been no added performance WHEN THE MANUFACTURER SAYS TO USE 87 GAS. To make the generalization that premium will ALWAYS give you higher power FOR OUR CAR is just wrong. Technically, you're not going to hurt your car with premium gas either. You are just wasting your money for no added benefit.

Your statement that 87 gas won't hurt anything is important. Those who use premium gas so their engines will last longer are clearly wrong and you and I would agree on that. So, for argument's sake, let's say you do have a power increase with premium fuel. The first question is how much of an increase will it be. In the testing I've seen for other cars WHERE THE MANUAL SAYS THAT PREMIUM WILL GIVE YOU ADDED HP, the increase is in the range of 5%, i.e., 20hp for a 400hp engine. In these engines, when you use 87 gas, your car is detuned. (It is NOT detuned for our car). So let's say that you can achieve half that result, or 2.5% or about 6hp on the 2.0 turbo. Because of engine dynamics, that 6 hp will only be fully useful when the engine is pushed -- not when you are driving normally. So, you MIGHT get it when passing a car or accelerating on the freeway. The question for the owner then comes down to how much extra money do you want to spend for a slight performance increase useful only a small part of driving time.

I've seen a few tests where using premium actually decreases power. I have trouble believing this, but they were done by competent organizations and mostly in Hondas. It seems you can program the ECM to provide more economy with higher octane gas and this actually decreases hp. This strategy would make sense if you are selling economy vehicles. I don't know if Kia does this and until our car is tested, there's no way of getting this answer.

Much of what happens when we buy a car, given that it is one of the most expensive purchases by most of us, is that we are human and it affects our psychology. We want to treat it well as if it was a member of the family. So we clean it often, we buy "jewelry" for it, and we "feed" it the very best. Is this really necessary? No, but it makes us feel better. I've changed the Kia logos and put a trim ring on my steering wheel. Does this make the car perform better? Again, we both agree that premium will not make your engine last longer and your car just doesn't need it.

I guess I just don't know how you can make your generalizations with the abundance of tests by competent organizations saying there is NO benefit for using premium fuel in cars designed to use regular. They clearly don't agree with you. Don't get me wrong, your argument does make "common sense" based on generalizations. And, it was exactly what I believed over a decade ago when I retired and had the time to research issues like this. The research changed my mind from the simple "common sense" argument, to a more sophisticated understanding.

In the end, what's important here, is that there is no benefit to the HEALTH of your car in using premium fuel. And we both agree on that. There might be a very slight power increase if your generalizations are true for our specific car, but is that worth all of the extra money you pay for it? For me, after doing all of my research, tuning track cars, and actually visiting engine manufacturing facilities and talking with the engineers, I just don't buy the generalization FOR OUR CAR. So, are you willing to spend all of that money for the life your compact, economy SUV just on the speculation that there might be a power increase that's only usable a small part of your driving time????? Hmmmm.... The answer for me is clearly no....
I am pleased you finally agreed that an engine can reach higher levels of HP output on Higher Octane Fuel.
Its actually higher than 6 HP. More like 10 to 15, as measured on a chassis dyno. And, that was the basis of this thread that the OP raised the question. Max HP. Have a blessed day!
 

·
Registered
Joined
·
421 Posts
The only way premium gas will affect engine performance is if you can tune the ECU for it. And then you can't go back without retuning it.
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
I am pleased you finally agreed that an engine can reach higher levels of HP output on Higher Octane Fuel.
Its actually higher than 6 HP. More like 10 to 15, as measured on a chassis dyno. And, that was the basis of this thread that the OP raised the question. Max HP. Have a blessed day!
I guess you didn't read my response. Let me spell it out for you.... THERE IS NO ADDED HORSEPOWER IN USING HIGHER OCTANE FUEL FOR OUR SPORTAGE. THIS IS BECAUSE OUR CAR WAS DESIGNED TO USE 87 OCTANE. YOU ONLY GET AN INCREASE IN CARS DESIGNED FOR THAT PURPOSE. That's why this is a complicated subject. I was trying to explain why there isn't a simple answer, but you do have to read my response to understand it. Please don't spread misinformation to others who read this forum and are not geeks like me who actually read the research and speak to engine designers/modifiers.
 
  • Like
Reactions: JoeW

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
The only way premium gas will affect engine performance is if you can tune the ECU for it. And then you can't go back without retuning it.
I would generally agree with you, and in many cases this is true. However, tuning really only works well if you have modified the engine and want to take advantage of that mod. For example, if you use E85 gas or put on headers. The car's ECM constantly tries to maximize performance/mileage unlike older cars where the parameters are set. The most important factor in higher octane gas is the compression ratio, and that will not change even if you tune the car. There are some small safety factors built into the ECM but for every change you make to it, there are both positive and negative results. I've tuned track cars (with the help of experts, of course), and I was surprised now little I got from it. They used to sell "chips" for cars to change the tune, but most of them didn't do much, if anything. You can actually get more performance by changing the shift points than doing tunes. I always run my car in SPORT mode for that reason.

If you want to really waste your money (I don't), bring your car to a tuner and see if you can increase the dyno results. I've done it with a number of track cars and always turn out disappointed.
 

·
Registered
2017 Kia Sportage SX
Joined
·
837 Posts
I have had several different turbocharged engines and have a basis to have some input on this.
Some vehicles, usually higher performance or sport oriented models, will require a minimum octane level to achieve a specified output. At the same time, they will state can run up to xx octane and get xx more hp due to that. These are engines that were specifically engineered to adjust to the octane level.
I don't know 100% the logic or reasoning that leads to some being like that. I can only assume this is a compromise as they know the higher octane fuels might not be available everywhere that vehicle will be sold, and it is a compromise to get the higher output if possible as desired.

That being said, the 2.0 t-gdi engine we have in the Sportage SX model doesn't seem to be among those.
The vehicles I have had, that were able to adapt, the HP gain was generally in the 6 - 10 hp range, and honestly you would be hard pressed to even notice it. But, specs are something a percentage of people get carried away over.
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
I have had several different turbocharged engines and have a basis to have some input on this.
Some vehicles, usually higher performance or sport oriented models, will require a minimum octane level to achieve a specified output. At the same time, they will state can run up to xx octane and get xx more hp due to that. These are engines that were specifically engineered to adjust to the octane level.
I don't know 100% the logic or reasoning that leads to some being like that. I can only assume this is a compromise as they know the higher octane fuels might not be available everywhere that vehicle will be sold, and it is a compromise to get the higher output if possible as desired.

That being said, the 2.0 t-gdi engine we have in the Sportage SX model doesn't seem to be among those.
The vehicles I have had, that were able to adapt, the HP gain was generally in the 6 - 10 hp range, and honestly you would be hard pressed to even notice it. But, specs are something a percentage of people get carried away over.
This behavior has more to do with marketing than engineering considerations. If you could get higher octane gas at the same price as regular, all cars would be designed to use the highest octane gas. Since the primary benefit of higher octane is being able to use a higher compression ratio (and not give more power or additives), you would always use premium in every car and there would be no benefit to using any higher octane like racing fuel. So most compact cars like ours are designed to not get any benefit from higher octane gas because the vast majority of buyers don't consider this to be a performance vehicle. Cars that are specifically performance vehicles, like my sports car, REQUIRE higher octane gas because most buyers bought this type of car for performance. If a car has a significant number of buyers who are concerned with the cost of gas and also a large group of buyers who want performance, then they design the car for both depending on what octane gas you buy. I used to have a BMW designed to get more hp out of premium gas. All of this is done by design. Fundamentally, what the engineers do is optimize performance for premium and then use the knock sensor to detune for regular. While it's not quite that simplistic since there are many variables programmed into the ECU, it is basically true. Designing a car to use both regular and premium fuel is more costly because your testing regimen must include both factors. That's why most inexpensive cars don't have this feature.

That said, no matter what facts you put in front of someone, there are people who are going to give mystical qualities to premium gas from more power to more additives. They have to justify themselves paying more for something. It's more about psychology than technology. Gas companies have been taking advantage of this behavior through marketing things like having extra additives in their premium gas and by not communicating what premium gas really does. In point of fact, the "extra" additives used do nothing for performance or protection over those additives require for Top Tier gas. This comes from the days before Top Tier where good additives were not required to be in gas. Even in our manual, Kia states that fuel additives are only required if you don't use Top Tier gas -- but then again, most people don't read the manual....
 

·
Registered
2022 Kia Sportage SX AWD
Joined
·
68 Posts
This behavior has more to do with marketing than engineering considerations. If you could get higher octane gas at the same price as regular, all cars would be designed to use the highest octane gas. Since the primary benefit of higher octane is being able to use a higher compression ratio (and not give more power or additives), you would always use premium in every car and there would be no benefit to using any higher octane like racing fuel. So most compact cars like ours are designed to not get any benefit from higher octane gas because the vast majority of buyers don't consider this to be a performance vehicle. Cars that are specifically performance vehicles, like my sports car, REQUIRE higher octane gas because most buyers bought this type of car for performance. If a car has a significant number of buyers who are concerned with the cost of gas and also a large group of buyers who want performance, then they design the car for both depending on what octane gas you buy. I used to have a BMW designed to get more hp out of premium gas. All of this is done by design. Fundamentally, what the engineers do is optimize performance for premium and then use the knock sensor to detune for regular. While it's not quite that simplistic since there are many variables programmed into the ECU, it is basically true. Designing a car to use both regular and premium fuel is more costly because your testing regimen must include both factors. That's why most inexpensive cars don't have this feature.

That said, no matter what facts you put in front of someone, there are people who are going to give mystical qualities to premium gas from more power to more additives. They have to justify themselves paying more for something. It's more about psychology than technology. Gas companies have been taking advantage of this behavior through marketing things like having extra additives in their premium gas and by not communicating what premium gas really does. In point of fact, the "extra" additives used do nothing for performance or protection over those additives require for Top Tier gas. This comes from the days before Top Tier where good additives were not required to be in gas. Even in our manual, Kia states that fuel additives are only required if you don't use Top Tier gas -- but then again, most people don't read the manual....
This begs the question - what are the non-Top Tier stations selling? Is it simply the same fuel without additives? Or is it a lower grade fuel? Same fuel with lesser grade additives?
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
This begs the question - what are the non-Top Tier stations selling? Is it simply the same fuel without additives? Or is it a lower grade fuel? Same fuel with lesser grade additives?
The EPA started requiring minimal additives in all gas in the early 1990's. Then, some auto manufacturers and gas companies banded together to form the Top Tier spec in about 2004. The benefit for the auto companies is that their warranties became more effective because of less engine problems. Given that Top Tier gas normally costs about 3 cents per gallon more on average, there was a profit and quality motive for the gas companies. All gas must follow the EPA spec, but only Top Tier gas has the additional additives that the manufacturer wants you to have for your car. Most cheap gas from non-major brands are not Top Tier certified. Top Tier gas suppliers must have their gas tested to adhere to the standards. Here's the current list of Top Tier brands...

  • 76 (USA)
  • ARCO (USA, Mexico)
  • Aloha (USA)
  • Amoco (USA)
  • BP (USA)
  • Beacon (USA)
  • Break Time C Stores (USA)
  • Breakaway (USA, Canada)
  • CITGO (USA)
  • Cenex (USA)
  • Chevron (USA, Canada, Mexico, Guatemala, Honduras, Panama, El Salvador, Colombia)
  • Co-op (Canada)
    • Co-op Diesel (Canada - select locations only)
  • Conoco (USA)
  • Costco Wholesale (USA, Canada, Mexico)
    • Costco Wholesale - Diesel (USA - select locations only, Canada - select locations only)
  • CountryMark (USA)
  • CountryMark PLUS (USA)
  • Diamond Shamrock (USA)
  • Energy (Mexico)
  • Esso (Canada)
  • Express Mart (USA - Wisconsin)
  • Exxon (USA)
  • Fast Fuel (USA)
  • Fast Stop - Diesel (USA - select locations only)
  • Fast Stop Express - Diesel (USA - select locations only)
  • G500 (Mexico)
  • HFN - Hawaii Fueling Network (USA)
  • Harmons Fuel Stop (USA)
  • Hele (USA)
  • Holiday (USA)
  • Irving Oil (USA, Canada)
  • Kirkland Signature Gasoline (USA, Canada, Mexico)
    • Kirkland Signature - Diesel (USA - select locations only, Canada - select locations only)
  • Kwik Star (USA)
  • Kwik Trip (USA)
  • MFA Oil (USA)
  • Marathon (USA)
  • Metro Petro (USA)
  • Meijer (USA)
  • Mobil (USA, Canada)
  • Ohana Fuels (USA)
  • PUMA (Guatemala, El Salvador, Honduras, Panama, Puerto Rico)
  • Phillips 66 (USA, Puerto Rico)
  • QT (USA)
  • QuikTrip (USA)
  • Ranger (USA)
  • Ranger Fuel (USA)
  • Ranger Mustang (USA)
  • Ranger Stallion (USA)
  • Ranger Thoroughbred (USA)
  • Reeder's (USA)
  • Road Ranger (USA)
  • Rutter's (USA)
  • Shamrock (USA)
  • Shell (USA, Canada, Puerto Rico)
  • Simonson Station Stores (USA)
  • Sinclair (USA)
  • Sunoco (USA)
  • Tempo (Canada)
  • Texaco (USA, Canada, Panama, Guatemala, Honduras, El Salvador, Colombia)
  • Tobacco Outlet Plus Grocery (USA)
  • Ultra Top Fuel (Puerto Rico)
  • Valero (USA)
  • Value America (USA)
  • WOW (USA)
  • Win Win (USA)
  • YPF (Argentina)
Fuel additive companies don't really want you to understand the Top Tier spec as fuel additives are unnecessary if you use Top Tier gas. If the gas you are buying is cheap, you might not be using Top Tier gas. This is a perfect example of you get what you pay for (as long as it's not a myth).....
 

·
Premium Member
2017 Sportage SX AWD / Mineral silver with beige interior
Joined
·
1,112 Posts
I was just in Kansas and the pump's don't state if it's top tier gas. I Googled BP and it is top tier. WAY CHEAPER in Kansas too and they don't have 85% octane like Colorado.
87% is is their cheapest and I pay about 40 cents more for it here in Colorado.
 

·
Registered
2021 Sportage SX 2.0T-GDI AWD
Joined
·
85 Posts
I have a 2021 SX Turbo, and have these same questions and issues.

First a note: at higher altitude, like myself in Denver, 'regular' gas is 85 octane and 'premium' is 91 octane. So I will use the terms, not the numbers.

I am in full agreement about the common confusion many owner/drivers have about additives, and about 'more HP' with higher octane. And I'm in agreement that it has a lot to do with how modern engines operate when managed by modern ECU especially in conjunction with detectors.

BUT ... what I have noticed in direct experience (I've spent a lot of tanks of gas a time comparing):

'regular' gas - my 2021 SX Turbo has a LOT of what i term hesitancy ... I think it's partly turbo lag, and partly transmission shift lag. But it makes it nearly impossible to drive "smoothly", especially pulling away from a stop ... you're either lugging very slowly, or just the tinyiest bit more gas and the turbo kicks and the transmission shifts down and everything jerks and you zoom away to 40mph before you know it

'premium' gas - 95% of that problem goes away, and the vehicle is MUCH smoother.

This is VERY annoying to me, and I really wish it was not so. Grrrrrrrr
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
I have a 2021 SX Turbo, and have these same questions and issues.

First a note: at higher altitude, like myself in Denver, 'regular' gas is 85 octane and 'premium' is 91 octane. So I will use the terms, not the numbers.

I am in full agreement about the common confusion many owner/drivers have about additives, and about 'more HP' with higher octane. And I'm in agreement that it has a lot to do with how modern engines operate when managed by modern ECU especially in conjunction with detectors.

BUT ... what I have noticed in direct experience (I've spent a lot of tanks of gas a time comparing):

'regular' gas - my 2021 SX Turbo has a LOT of what i term hesitancy ... I think it's partly turbo lag, and partly transmission shift lag. But it makes it nearly impossible to drive "smoothly", especially pulling away from a stop ... you're either lugging very slowly, or just the tinyiest bit more gas and the turbo kicks and the transmission shifts down and everything jerks and you zoom away to 40mph before you know it

'premium' gas - 95% of that problem goes away, and the vehicle is MUCH smoother.

This is VERY annoying to me, and I really wish it was not so. Grrrrrrrr
Most ECM programming today is complex. Normally, most past engines in high altitude will perform OK on 85 octane. This dates back to the use of carburetors but is less true for direct injection. As car makers try to squeeze as much as they can (i.e., max the compression ratio and still use 87 octane gas), this is becoming less true. So, it is recommended by most manufacturers that if you live in a higher altitude and 85 octane isn't working well, move to mid grade, which should be 87 octane. In fact, GM manufacturers specifically state in a number of articles that it doesn't matter if you live in a high altitude, if the manual calls for 87 octane that's what you should use. In fact, there should still be no reason to go all of the way to premium. If you look in the manual, there is no exception for using 87 octane gas as a minimum even in high altitudes. In a few states, there have been laws passed that require a statement on the pumps that the octane level may not meet manufacturer requirements. My recommendation to you is to follow the manual and never put lower than 87 octane into your car. When I've travelled through Denver before, I always have put at least mid-grade gas in my cars....
 

·
Registered
2021 Sportage SX 2.0T-GDI AWD
Joined
·
85 Posts
Interesting ... I re-check the manual recommendation. The last time I read the fuel section of a manual, it mentioned absolutely nothing about altitude at all.

Of course, I fill 80% at Costco, where there is no mid-grade option (only regular/premium) 🤷‍♂️

Full disclosure - I don't think in my entire life I've ever bought a tank of mid-grade gas - it will seem very strange. And of course like everywhere, gas prices have risen in Denver, with regular-grade averaging about $3.60/gal right now (yikes).


Most ECM programming today is complex. Normally, most past engines in high altitude will perform OK on 85 octane. This dates back to the use of carburetors but is less true for direct injection. As car makers try to squeeze as much as they can (i.e., max the compression ratio and still use 87 octane gas), this is becoming less true. So, it is recommended by most manufacturers that if you live in a higher altitude and 85 octane isn't working well, move to mid grade, which should be 87 octane. In fact, GM manufacturers specifically state in a number of articles that it doesn't matter if you live in a high altitude, if the manual calls for 87 octane that's what you should use. In fact, there should still be no reason to go all of the way to premium. If you look in the manual, there is no exception for using 87 octane gas as a minimum even in high altitudes. In a few states, there have been laws passed that require a statement on the pumps that the octane level may not meet manufacturer requirements. My recommendation to you is to follow the manual and never put lower than 87 octane into your car. When I've travelled through Denver before, I always have put at least mid-grade gas in my cars....
 

·
Registered
2021 Sportage SX 2.0T-GDI AWD
Joined
·
85 Posts
The manual for my 2021 Sportage SX Turbo says only to use 87 octane. I can find no mention anywhere in the manual of altitude recommendations for fuel or anything else in vehicle operation.

The 'conventional wisdom' is

1) at higher elevation, 85 octane is typically sold as 'regular', which is 87 octane at lower elevation
2) modern engines with knock and pre-knock detectors shouldn't have human perceptible knock at all, but regardless, in any engine if there is knock, higher octane fuel is indicated
3) I'm not having knock per se, just 'hesitancy', but likely higher octane will help

Too bad I'm a cheap bastard that would prefer not to pay extra, lol.

I'll probably try a few tanks of 87 octane (which is so-called mid-grade in Denver), and see how it goes. 🤷‍♂️


Interesting ... I re-check the manual recommendation. The last time I read the fuel section of a manual, it mentioned absolutely nothing about altitude at all.

Of course, I fill 80% at Costco, where there is no mid-grade option (only regular/premium) 🤷‍♂️

Full disclosure - I don't think in my entire life I've ever bought a tank of mid-grade gas - it will seem very strange. And of course like everywhere, gas prices have risen in Denver, with regular-grade averaging about $3.60/gal right now (yikes).
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
The manual for my 2021 Sportage SX Turbo says only to use 87 octane. I can find no mention anywhere in the manual of altitude recommendations for fuel or anything else in vehicle operation.

The 'conventional wisdom' is

1) at higher elevation, 85 octane is typically sold as 'regular', which is 87 octane at lower elevation
2) modern engines with knock and pre-knock detectors shouldn't have human perceptible knock at all, but regardless, in any engine if there is knock, higher octane fuel is indicated
3) I'm not having knock per se, just 'hesitancy', but likely higher octane will help

Too bad I'm a cheap bastard that would prefer not to pay extra, lol.

I'll probably try a few tanks of 87 octane (which is so-called mid-grade in Denver), and see how it goes. 🤷‍♂️
There is a reason the manual does not mention 85 octane at all. Don't substitute "conventional wisdom" for scientific fact and what is in your manual. Many of us are cheap bastards which is one reason I never put premium in the car (besides the fact that it doesn't help). 85 octane at higher elevations is a remnant of the time carburetors were used instead of fuel injection. Pressured fuel systems are not as sensitive to altitude. Your car was tested and designed with the limits in your manual. So use them...
 

·
Registered
2021 Sportage SX 2.0T-GDI AWD
Joined
·
85 Posts
Thanks. Good point on pressurized fuel systems. I'll do some Real World Testing (sample size = 1), and update.

There is a reason the manual does not mention 85 octane at all. Don't substitute "conventional wisdom" for scientific fact and what is in your manual. Many of us are cheap bastards which is one reason I never put premium in the car (besides the fact that it doesn't help). 85 octane at higher elevations is a remnant of the time carburetors were used instead of fuel injection. Pressured fuel systems are not as sensitive to altitude. Your car was tested and designed with the limits in your manual. So use them...
 

·
Registered
2021 Sportage S 2.4 FWD
Joined
·
292 Posts
My owners manual says to use USA 87 or higher. It doesn't say only 87. I am in the USA as octane measurement scales around the world can be different. You do NOT have an option for USA 85 regardless of your altitude.

1. 85 isn't listed in the owners manual. Since air is thinner at attitude, 85 is great for naturally aspirated vehicles to help reduce power loss. Since a turbo creates its own boost, it doesn't get that option of running 85.
2. I heard detonation in too many Hyundai/Kia products over the years. And, there is a limit on how much correction can be ECU applied when the knock sensor gets vocal. Its pretty obvious when timing gets cut with drivability. Takes a non-zombie driver since most US consumers tend to be sheeple.
3. With a turbo, premium fuel is the only conventional wisdom. The ecu will push the threshold for maximum power/efficiency/mpg depending on what the gas pedal is doing. If you want the most power, you use premium fuel. If you are a happy drone cheapskate commuter, than 87 is fine. Weather and load has a lot to do whether its very obvious versus barely perceptible.
4. You don't need a tune to benefit from premium fuel. The tune is there already and always detuning because of how vocal the knock sensor gets.
5. The 2.0T's that I've seen on the dyno(Optima/Sonata) all made 10-15 more HP with premium fuel and they showed more timing advance. I haven't seen a Sportage on a dyno but would wager the sibling to be the same. There is more to a dyno than simple peak power... area under the curve and drivability... things that a driver with a pulse will notice.

Mazda is one of the few automakers honest about their turbo power... giving different HP ratings for octane. And others simply recommend premium fuel for 'best performance' or other marketing, which is what your owners manual shows... marketing for the masses.

I doubt anyone posting in this thread has ever worked on a turbo engine, dyno, or with fuel. Thread is laughable.
If you want maximum power from a turbocharged car, you use premium. That is all.
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
My owners manual says to use USA 87 or higher. It doesn't say only 87. I am in the USA as octane measurement scales around the world can be different. You do NOT have an option for USA 85 regardless of your altitude.

1. 85 isn't listed in the owners manual. Since air is thinner at attitude, 85 is great for naturally aspirated vehicles to help reduce power loss. Since a turbo creates its own boost, it doesn't get that option of running 85.
2. I heard detonation in too many Hyundai/Kia products over the years. And, there is a limit on how much correction can be ECU applied when the knock sensor gets vocal. Its pretty obvious when timing gets cut with drivability. Takes a non-zombie driver since most US consumers tend to be sheeple.
3. With a turbo, premium fuel is the only conventional wisdom. The ecu will push the threshold for maximum power/efficiency/mpg depending on what the gas pedal is doing. If you want the most power, you use premium fuel. If you are a happy drone cheapskate commuter, than 87 is fine. Weather and load has a lot to do whether its very obvious versus barely perceptible.
4. You don't need a tune to benefit from premium fuel. The tune is there already and always detuning because of how vocal the knock sensor gets.
5. The 2.0T's that I've seen on the dyno(Optima/Sonata) all made 10-15 more HP with premium fuel and they showed more timing advance. I haven't seen a Sportage on a dyno but would wager the sibling to be the same. There is more to a dyno than simple peak power... area under the curve and drivability... things that a driver with a pulse will notice.

Mazda is one of the few automakers honest about their turbo power... giving different HP ratings for octane. And others simply recommend premium fuel for 'best performance' or other marketing, which is what your owners manual shows... marketing for the masses.

I doubt anyone posting in this thread has ever worked on a turbo engine, dyno, or with fuel. Thread is laughable.
If you want maximum power from a turbocharged car, you use premium. That is all.
Again, this is misinformation. The reason the manual says 87 or higher is that 87 may not always be available AND IS A MINIMUM. The option is for the manual to say ONLY 87 which is a foolish statement. You are assuming that when you use 87 octane gas, your car has retarded the spark. In some cars this is true, but when an engine is designed/maximized to use 87 octane gas, the knock sensor is only there to prevent engine damage in case you get bad gas -- or in the case of Denver, 85 octane gas. If we were talking about turbos 10 years ago, then I might tend to agree with you. And if you tested on gas that was not rated Top Tier, that's another factor. But there has been significant developments in engine design especially with the increasing power of supercomputers and the power of the computers in your car. Many tests by reputable sources have been done in recent years. I've previously actually listed many of the articles. There are still cars produced that get a slight benefit from higher octane gas like Ford's Ecoboost engines, but that is in the range of 1-2% and only exists in the higher horsepower versions.

You cannot take results from turbos tested years ago, when engines were less sophisticated, and apply them today. Those cars that recommend premium fuel for "best performance" are designed that way. I have a sports car that recommends premium fuel for best performance. In fact, at the fuel door, it says to use premium fuel. If you use regular, you lose significant power, but it won't hurt the car. And yes, I used to track a number of cars and had turbos, many dyno tests, and used racing fuels far above premium. Most engine designers today, would love to use higher octane gas to maximize engine performance. I think the current high optimization number is about 113 octane. But the cost of providing that kind of gas is huge. What is laughable is to believe that what was true in the past is true today and that all of the reputable sources saying something different are all lying.

And if all of this was not enough, even when testing those cars that got added power with premium on the track, the lap times were almost identical which means that in real life, you can't really feel an improvement and if you do, it's more psychological than real. So consider this.... If you can't objectively get added power on the track, and regular fuel won't hurt your car (using Top Tier fuels), what's the benefit?????

Again, there is nothing wrong with using higher octane gas if you don't care about money and get some psychological benefit. It certainly won't hurt your car. But it reminds me of the type of performance improvements done by ricers, i.e., CAI's, K&N filters, less restrictive mufflers, etc. You think you're getting a race car, but it's still a compact SUV.... (and a very good one, by the way...)
 

·
Registered
2020 Kia Sportage SX AWD and 1988 Mercedes 300CE
Joined
·
456 Posts
Again, this is misinformation. The reason the manual says 87 or higher is that 87 may not always be available AND IS A MINIMUM. The option is for the manual to say ONLY 87 which is a foolish statement. You are assuming that when you use 87 octane gas, your car has retarded the spark. In some cars this is true, but when an engine is designed/maximized to use 87 octane gas, the knock sensor is only there to prevent engine damage in case you get bad gas -- or in the case of Denver, 85 octane gas. If we were talking about turbos 10 years ago, then I might tend to agree with you. And if you tested on gas that was not rated Top Tier, that's another factor. But there has been significant developments in engine design especially with the increasing power of supercomputers and the power of the computers in your car. Many tests by reputable sources have been done in recent years. I've previously actually listed many of the articles. There are still cars produced that get a slight benefit from higher octane gas like Ford's Ecoboost engines, but that is in the range of 1-2% and only exists in the higher horsepower versions.

You cannot take results from turbos tested years ago, when engines were less sophisticated, and apply them today. Those cars that recommend premium fuel for "best performance" are designed that way. I have a sports car that recommends premium fuel for best performance. In fact, at the fuel door, it says to use premium fuel. If you use regular, you lose significant power, but it won't hurt the car. And yes, I used to track a number of cars and had turbos, many dyno tests, and used racing fuels far above premium. Most engine designers today, would love to use higher octane gas to maximize engine performance. I think the current high optimization number is about 113 octane. But the cost of providing that kind of gas is huge. What is laughable is to believe that what was true in the past is true today and that all of the reputable sources saying something different are all lying.

And if all of this was not enough, even when testing those cars that got added power with premium on the track, the lap times were almost identical which means that in real life, you can't really feel an improvement and if you do, it's more psychological than real. So consider this.... If you can't objectively get added power on the track, and regular fuel won't hurt your car (using Top Tier fuels), what's the benefit?????

Again, there is nothing wrong with using higher octane gas if you don't care about money and get some psychological benefit. It certainly won't hurt your car. But it reminds me of the type of performance improvements done by ricers, i.e., CAI's, K&N filters, less restrictive mufflers, etc. You think you're getting a race car, but it's still a compact SUV.... (and a very good one, by the way...)
Serious question: since you state that our cars do not retard spark, what does happen when the knock sense picks up detonation? Obviously not all pumps labeled as 87 are going to give you precisely 87 (some maybe higher, some lower), some when you buy what is labeled as 87 and it is in fact closer to 85, how does the computer compensate for any detonation that may occur?

Sent from my SM-N986U using Tapatalk
 

·
Registered
2017 Kia Sportage
Joined
·
1,632 Posts
Serious question: since you state that our cars do not retard spark, what does happen when the knock sense picks up detonation? Obviously not all pumps labeled as 87 are going to give you precisely 87 (some maybe higher, some lower), some when you buy what is labeled as 87 and it is in fact closer to 85, how does the computer compensate for any detonation that may occur?

Sent from my SM-N986U using Tapatalk
I did not say the car can't retard the spark, only that it is designed for maximum efficiency at 87 octane and AT THAT SETTING, the spark is not retarded. But, it is far more complex than that and for convenience sake, I've perhaps oversimplified. The ECU controls a number of factors including fuel regulation, boost pressure, timing, compensation for high load, etc. Since the car was designed to run/maximized at 87 octane, if you put in 85 octane a number of these parameters will change and the car will no longer run at maximum efficiency in order to protect the engine. But if you put in higher than 87 octane, since the car was already maximized, the higher octane does practically nothing. Again, this is a complex subject because some cars are DESIGNED to get more power from premium fuels. In the olden days, perhaps 5-10 years ago, you could get a very small hp increase in most cars. The quantum advance of computer power in cars increases like Moore's law so it can make adjustments now it could not make even 5 years ago. Different manufacturers have different design schemes. VW has a history of giving added hp with increased octane while Honda does not. Again, this is a complex subject. Those who are stuck in the past, believe increased octane will always give increased hp -- and I don't blame them for believing that because that is the way it used to be.

But this is a scientific/technical argument. Let's look at real life -- how you and a would drive a Sportage. If you look at the results of lap times when qualified entities tested octane differences in performance, lap times barely increased if at all, even in engines designed to use higher octane gas. So if you floor the car getting on to the freeway, even in cars with differences, you won't notice virtually any increased speed. One of the reasons for that is that with internal combustion engines, maximum hp is only reached at higher rpm's. So you are not getting any added hp at lower rpm's when you are accelerating. Now if you had a stick shift, you could pop the clutch -- but we all have automatics and do not have launch control. So for all that added money you spent on premium, in real life it's not doing you hardly any good. Much of what we do in our cars is psychological. We polish it, we get accessories we really don't need, we remove emblems. We liked the way the car looked or else we would not have purchased it. Many people change the oil at smaller intervals than the manual recommends. The engine doesn't need it, but it makes them feel better that they've taken car of their "baby". Since cars are our second largest purchase, in many ways, we want to take care of it in special ways. I am not immune to some of these things because it does make me feel better. But most of it is purely psychological. So I will put full synthetic in the engine even though my testing says it isn't absolutely needed IF I change the oil every 7500 miles on my EX. It does protect me, however, if I don't. Putting in premium fuel is the same thing -- it's psychological. They way I look at it, however, is that if it makes you feel better, and you have the extra money, being happy is OK and a good use of money. I spend those extra bucks donating to food banks and that is what makes me feel good since I've been rather lucky in life. I won't even wash my car often -- usually every other month. But I live in a place with little rain, I don't drive a whole lot any more, and the car is always garaged. When I lived back east, it was another matter.
 

·
Registered
2020 Kia Sportage SX AWD and 1988 Mercedes 300CE
Joined
·
456 Posts
I did not say the car can't retard the spark, only that it is designed for maximum efficiency at 87 octane and AT THAT SETTING, the spark is not retarded. But, it is far more complex than that and for convenience sake, I've perhaps oversimplified. The ECU controls a number of factors including fuel regulation, boost pressure, timing, compensation for high load, etc. Since the car was designed to run/maximized at 87 octane, if you put in 85 octane a number of these parameters will change and the car will no longer run at maximum efficiency in order to protect the engine. But if you put in higher than 87 octane, since the car was already maximized, the higher octane does practically nothing. Again, this is a complex subject because some cars are DESIGNED to get more power from premium fuels. In the olden days, perhaps 5-10 years ago, you could get a very small hp increase in most cars. The quantum advance of computer power in cars increases like Moore's law so it can make adjustments now it could not make even 5 years ago. Different manufacturers have different design schemes. VW has a history of giving added hp with increased octane while Honda does not. Again, this is a complex subject. Those who are stuck in the past, believe increased octane will always give increased hp -- and I don't blame them for believing that because that is the way it used to be.

But this is a scientific/technical argument. Let's look at real life -- how you and a would drive a Sportage. If you look at the results of lap times when qualified entities tested octane differences in performance, lap times barely increased if at all, even in engines designed to use higher octane gas. So if you floor the car getting on to the freeway, even in cars with differences, you won't notice virtually any increased speed. One of the reasons for that is that with internal combustion engines, maximum hp is only reached at higher rpm's. So you are not getting any added hp at lower rpm's when you are accelerating. Now if you had a stick shift, you could pop the clutch -- but we all have automatics and do not have launch control. So for all that added money you spent on premium, in real life it's not doing you hardly any good. Much of what we do in our cars is psychological. We polish it, we get accessories we really don't need, we remove emblems. We liked the way the car looked or else we would not have purchased it. Many people change the oil at smaller intervals than the manual recommends. The engine doesn't need it, but it makes them feel better that they've taken car of their "baby". Since cars are our second largest purchase, in many ways, we want to take care of it in special ways. I am not immune to some of these things because it does make me feel better. But most of it is purely psychological. So I will put full synthetic in the engine even though my testing says it isn't absolutely needed IF I change the oil every 7500 miles on my EX. It does protect me, however, if I don't. Putting in premium fuel is the same thing -- it's psychological. They way I look at it, however, is that if it makes you feel better, and you have the extra money, being happy is OK and a good use of money. I spend those extra bucks donating to food banks and that is what makes me feel good since I've been rather lucky in life. I won't even wash my car often -- usually every other month. But I live in a place with little rain, I don't drive a whole lot any more, and the car is always garaged. When I lived back east, it was another matter.
I'm not sure what horsepower has to do with spark knock or low rpm acceleration. Torque on the other hand is directly impacted by both. Low rpm acceleration is one of the peak conditions resulting in detonation. Detonation results in less sustained push on the piston, providing less torque at the crank. Retarding the spark, or any other means that the ECU can take to reduce detonation, results in a less efficient combustion versus piston position. Once again, less torque (the necessary force required for acceleration).

I do concur with the rest of your argument regarding not getting an increase in power (hp or torque) by using more than 87 octane in our engines. But, I error on the side of pumping a higher octane to ensure that I always am getting at least 87 octane (I can assure you that even at Tier 1 stations of the same brand, the octane rating of the fuel dispensed can vary from station to station.

Sent from my SM-N986U using Tapatalk
 
21 - 40 of 42 Posts
Top