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Discussion Starter · #1 ·
So, I've been using shell 91 in my K5GT since I got it 8 months ago.
For me, it's not about fuel mileage but rather performance. The only way we can tell is if someone data logs while on 87 octane and then data logs with higher octane to see if there's timing being pulled or on lower octane.
 

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2021 Phantom Black Sonata N-Line
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I've done the same since I got my N-Line back in March. I know it's tuned to run on 87 and that's fine, but for me I prefer to run 91 in a turbo car. I've done this with my Sonata 2.0t, Santa Fe 2.0t, Genesis 3.3t, Elantra Sport, HHR SS, Eclipse GS-T and Juke Nismo RS. I know some will say it's a waste of money to run 91 in a car that's tuned for 87, but who cares, it's my money. Now, let me go put on my flame proof suit because I can feel the heat coming 馃ぃ
 

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Discussion Starter · #3 ·
Why would they specify "87 or higher"?
I'd say in a n/a car, going higher is pointless.
But in a modern turbo where ecu can adjust, why not. The question is, does 91 allow for timing advancement enough to warrant the price difference? If on 87 we can get 14.2 1/4 mile and on 91 or higher we can manage high 13s...its all worth it Imo.
 

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I suppose the only real way to know would be to run dyno runs on the same day, same conditions, one with 87 and one with 93. Also not all 87 is the same, for instance here in MI most 87 is not a blend. Just because Hyundai says it is "tuned" for 87, does not mean that 87 will give you the best performance. It means that unlike many of the higher performance turbo cars that mfr. state higher octane is required, Hyundai has dumbed down the map to assume 87. Now does that mean that if the car has 93 the map will allow less timing to be pulled? If there is less detonation will the map allow different boost pressure, and if so where? That's the million dollar question. As has been pointed out, other manufacturers definitely do that, like Mazda, BMW and Audi. Look at JB4 maps, you can't run the same ECM parameters with 87 and 93, period, that's what is lost on the "it's a scam" crowd, it isn't a scam if you don't lug along at 40 never being in a situation where the benefits of 93 become apparent. It isn鈥檛 a scam if the ECM will pull less timing, allow greater boost, adjust the transition points of the injection method, etc. How many racing genre's run 87, none, because you can get more power out of a higher octane fueling with corresponding engine management. So could the N line net higher HP when using 93? Absolutely, if the stock maps are smart enough to allow different parameters, but without one of the engineers the only way we'd know is same-same dyno runs with 87 and 93.
 

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87. Like you have already stated, until someone can prove it, just wasting cash (not judging). There is no evidence up to this point that says using higher will help in anyway - performance or fuel economy. In fact, just like mentioned in the numerous other threads (and above) regarding this topic, other manufacturers like Mazda and VW will list that you need to use the higher grade to achieve better mpgs and/or power. If Hyundai could have eked out more mpgs or more power, guessing they would have done the same.
Given the cost difference and the amount of miles I drive, last time I looked it would be over $500 extra per year for me to make the switch. I could do that, just don't see a point since I am happy with the performance and the car is happy drinking it up. The only "splurge" I do is go with a recommended top tier fuel vs the cheapest stuff that burns. Even that, the manual states to just run a fuel system cleaner through at each service interval for the same effect.
 

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other manufacturers like Mazda and VW will list that you need to use the higher grade to achieve better mpgs and/or power. If Hyundai could have eked out more mpgs or more power, guessing they would have done the same.
But not all mfr. do that, look at the Ford F-150 with a huge power jump from 93, they say nothing about different ratings at different octanes, they just write into their maps to accommodate either octane, and clearly allow less timing to be pulled and likely changes to boost map. With the N line being one of Hyundai's performance vehicles, albeit not their top tier, it would be pretty foolish in my eyes to not allow the ECM to make similar adjustments as Ford, BMW, VW, etc.

Not everyone buying this car falls in the don't care camp about an extra 10hp. Sonata markets the N line with its "beefy" engine, it "punches the throttle on performance", " power and handling get a big boost from the 290-hp engine and 19-inch wheels. So, get in and take off." To me it would be insulting to have the car only mapped for 87, why? this isn't an entry level Elantra, this is a performance car, and in this day and age it is widely known among performance enthusiasts that you absolutely can get more power out of these boosted motors with a higher octane if your ECM can adjust for it. Maybe Hyundai didn't do that, seems foolish if that is the case, but then I suppose quite a few of the people that care just go the JB4 route, where octane matters even more when running closer to the boost limits.
 

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But not all mfr. do that, look at the Ford F-150 with a huge power jump from 93, they say nothing about different ratings at different octanes, they just write into their maps to accommodate either octane, and clearly allow less timing to be pulled and likely changes to boost map. With the N line being one of Hyundai's performance vehicles, albeit not their top tier, it would be pretty foolish in my eyes to not allow the ECM to make similar adjustments as Ford, BMW, VW, etc.

Not everyone buying this car falls in the don't care camp about an extra 10hp. Sonata markets the N line with its "beefy" engine, it "punches the throttle on performance", " power and handling get a big boost from the 290-hp engine and 19-inch wheels. So, get in and take off." To me it would be insulting to have the car only mapped for 87, why? this isn't an entry level Elantra, this is a performance car, and in this day and age it is widely known among performance enthusiasts that you absolutely can get more power out of these boosted motors with a higher octane if your ECM can adjust for it. Maybe Hyundai didn't do that, seems foolish if that is the case, but then I suppose quite a few of the people that care just go the JB4 route, where octane matters even more when running closer to the boost limits.
I agree 100% ....
 

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Stormy Sea 2021 Sonata N-Line
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Here you go:

Higher octane matters on a turbo*

*For those that care more about tenths than anything else.
As someone who uses both in the N Line. I can't say there is much of a gain using premium for anything but WOT, and that's more to prevent engine retarding than actually gaining speed/time. Sure I like putting some premium Shell in for a couple of fills every once in a while for other benefits like the extra additives. But I only use Top Tier fuel anyway, so that might even be a waste.

If you are going to be dragging this car, yea you might get a tenth of a second on the quarter mile stock using Premium over reg, but the realistically the wheel spin on launch is your bottleneck. Doing 20 and 40 pulls I have never noticed a difference using the timers built into Torque, and that's my only reference as I don't own a Dragy or have easy or reasonably affordable access to a dyno around here.

Next time we have some stable weather and I am doing a switch from reg to premium I will get some screen caps of my Torque on some runs, just so we can have SOME real world comparisons for the people every time threads like this get started.

Essentially, if I go to a drag strip I will probably put premium in it, because its not going to hurt anything and could possibly benefit me. For typical driving around I will stick to what the car is tuned for and save some money.
 

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Honestly it's pointless. Especially if you always use top tier fuel like I do. My Alfa Romeo Giulia recommended premium fuel, which I always used. But speaking to people at Alfa, they literally fill all their vehicles up with 87. If you're running no name fuel, I'd probably stick with premium, otherwise top tier I wouldn't use anything more than 87. I definitely don't see any benefit especially here in Michigan where we have 93 octane, which I highly doubt would benefit a car that's tuned for 87. You're just pissing away $5+ every fill up.
 

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The only way we can tell is if someone data logs while on 87 octane and then data logs with higher octane to see if there's timing being pulled or on lower octane.
I'd like to see data logs taken when the ambient temp is 32+C, stop and go, AC cranking.
That's when some extra octane is most likely to help, turbo or NA.
When there's a heat wave ahead I'll add a 1/2 tank of premium to 87.
Makes a performance difference in my Tucson, as well as my previous 2006 Toyota Matrix.
It amounts to 1/2 to 1 tank of premium per year.
 

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But not all mfr. do that, look at the Ford F-150 with a huge power jump from 93, they say nothing about different ratings at different octanes, they just write into their maps to accommodate either octane, and clearly allow less timing to be pulled and likely changes to boost map. With the N line being one of Hyundai's performance vehicles, albeit not their top tier, it would be pretty foolish in my eyes to not allow the ECM to make similar adjustments as Ford, BMW, VW, etc.

Not everyone buying this car falls in the don't care camp about an extra 10hp. Sonata markets the N line with its "beefy" engine, it "punches the throttle on performance", " power and handling get a big boost from the 290-hp engine and 19-inch wheels. So, get in and take off." To me it would be insulting to have the car only mapped for 87, why? this isn't an entry level Elantra, this is a performance car, and in this day and age it is widely known among performance enthusiasts that you absolutely can get more power out of these boosted motors with a higher octane if your ECM can adjust for it. Maybe Hyundai didn't do that, seems foolish if that is the case, but then I suppose quite a few of the people that care just go the JB4 route, where octane matters even more when running closer to the boost limits.
But not all mfr. do that, look at the Ford F-150 with a huge power jump from 93, they say nothing about different ratings at different octanes, they just write into their maps to accommodate either octane, and clearly allow less timing to be pulled and likely changes to boost map. With the N line being one of Hyundai's performance vehicles, albeit not their top tier, it would be pretty foolish in my eyes to not allow the ECM to make similar adjustments as Ford, BMW, VW, etc.

Not everyone buying this car falls in the don't care camp about an extra 10hp. Sonata markets the N line with its "beefy" engine, it "punches the throttle on performance", " power and handling get a big boost from the 290-hp engine and 19-inch wheels. So, get in and take off." To me it would be insulting to have the car only mapped for 87, why? this isn't an entry level Elantra, this is a performance car, and in this day and age it is widely known among performance enthusiasts that you absolutely can get more power out of these boosted motors with a higher octane if your ECM can adjust for it. Maybe Hyundai didn't do that, seems foolish if that is the case, but then I suppose quite a few of the people that care just go the JB4 route, where octane matters even more when running closer to the boost limits.
I totally understand your stance and angle you are taking on this, as well as others who push the use of something like 89, 91 or 93 octane. Nice to be in a forum that discusses this without ripping each others heads off. In the age of Hyundai replacing engines in many cars, I would imagine they will lean conservative on this. If they realized it made more power or was more efficient then they would likely want to capitalize on that, especially given how important fleet mpg averages are for manufacturers these days. The only way to settle this is to do some dyno runs using the same car, same conditions, different octane fuel. We all have seen runs and magazine testing that differs greatly, car to car as well as influence from the test environment (road conditions, weather, tire wear, driver competence, etc).
I have seen a few octane comparison articles/videos, including the C&D one above where using one vs the other concludes with practically no benefit. A tenth or two (+ or -, you seem to be focusing on the 1/4 vehicles tested that showed a decent gain but forgetting about the other 3) is easily noise in acceleration testing, same with the fuel economy. Anyway, like I said, spending an extra $500 a year for me, assuming that it helped even a little, just to get a tenth or 2 maybe on few hard acceleration runs per tank where honestly I am more worried about traction so I can't mash the throttle anyway, seems like a waste.
I am all for someone testing and providing some data points. I am not sure it would change my mind in regards to using a different octane in it since I am happy with the performance I am getting, car seems happy to run on it, and I am not looking to overcook my car with any tunes since it is my daily driver that I need reliably to start every day at 5 am year round and get me 65-80+ miles per day. If this was a dedicated fun car, then I probably would be doing whatever small things that I could to it to maximize performance - anything other than maybe an intake or cat back exhaust would be too much for me on this car given that I want to preserve reliability for as long as possible.

For reference, here is a screenshot of the current F-150 manual for the 3.5 Eco Boost.
Rectangle Font Screenshot Software Number


Ford mentions that it will run fine on 87, but for best overall vehicle and engine performance, using 91 or higher is recommended. They admit the need as well, just like other mfgs listed previously. Hyundai is much more vague, stating 87 is the minimum. It certainly won't harm it but the jury is out until testing happens on if there is any significant and/or worthwhile benefit to going higher than 87.
Manual for the N Line:
Font Rectangle Circle Number Screenshot
 

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Discussion Starter · #17 ·
I can't say I disagree with what's being said so far. I don't have access to a dyno near by and don't have a jb4 to data log. So, I was asking for anyone that can data log, to provide logs so we can see if on a stock tune, the extra octane makes a difference. Someone over at that k5 forums, will do some dyno runs with a jb4 from map 0 to 5 and on lower octane vs higher octane.
Curious to see the outcome. I don't drive a lot to see a huge impact on fuel costs.
I know that on the optima 2.0T, kia engineers had said that on premium fuel, that platform makes an extra 10hp. Not astronomical but it's proof that the ecu compensates for various octane. I'll keep you guys posted once I get those numbers from the fellow K5GT owner.
 

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Someone over at that k5 forums, will do some dyno runs with a jb4 from map 0 to 5 and on lower octane vs higher octane.
Curious to see the outcome.
Me too, although I doubt all of the naysayers will coalesce into believers with the fact that "but it wasn't stock it had a JB4" if there are gains shown. This car isn't a Honda mini SUV that would have the number of performance enthusiast owners considered as noise in the statistics, this is a performance car, as I have already said. Without dyno runs this can go no further, but I firmly believe that Hyundai would be downright stupid to map this for 87 only with no gains for higher octane fuel. Sure they can market it as tuned for 87 to collect all of the commuters that would have been turned off the car by maps assuming higher octane fuel requiring that cringe worthy sticker on the fuel filler door. But Hyundai clearly wants a piece of the enthusiast market, 2 new full N models speaks to that, and they are succeeding, I was pulled to this car from my last 4 vehicles, a Macan GTS, Challenger Hellcat, Charger Scat Pack and Camaro ZL1, in no small part because of the engine. I needed something larger to drive routinely long distances to get my son to the hospital for his bone marrow transplant appointments, and leave in a parking garage without worrying about dings on an expensive car. Frankly I could care less about a few MPG, I want performance, I have tracked all of my previous vehicles, so I'll say for one last time, for some, tenths matter, if you don't get that fine, but that doesn't mean it isn't a thing to maximize the potential of the engine in whatever you drive. there are a few here who get that, I have a stack of dyno sheets from previous car tunes that speak to that. You are either in that camp or you aren't, so keep running your 87 if you want, it clearly is the right choice for you, but not sure why people want to dismiss that maybe there is a difference, maybe it matters to someone else, and so let me see if I can make time to run across the state to my usual dyno, I'd do it just to not have to see all the rebuttals anymore even though I really have no intent of tuning this car right now with everything else I have going on in life.
 

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Me too, although I doubt all of the naysayers will coalesce into believers with the fact that "but it wasn't stock it had a JB4" if there are gains shown. This car isn't a Honda mini SUV that would have the number of performance enthusiast owners considered as noise in the statistics, this is a performance car, as I have already said. Without dyno runs this can go no further, but I firmly believe that Hyundai would be downright stupid to map this for 87 only with no gains for higher octane fuel. Sure they can market it as tuned for 87 to collect all of the commuters that would have been turned off the car by maps assuming higher octane fuel requiring that cringe worthy sticker on the fuel filler door. But Hyundai clearly wants a piece of the enthusiast market, 2 new full N models speaks to that, and they are succeeding, I was pulled to this car from my last 4 vehicles, a Macan GTS, Challenger Hellcat, Charger Scat Pack and Camaro ZL1, in no small part because of the engine. I needed something larger to drive routinely long distances to get my son to the hospital for his bone marrow transplant appointments, and leave in a parking garage without worrying about dings on an expensive car. Frankly I could care less about a few MPG, I want performance, I have tracked all of my previous vehicles, so I'll say for one last time, for some, tenths matter, if you don't get that fine, but that doesn't mean it isn't a thing to maximize the potential of the engine in whatever you drive. there are a few here who get that, I have a stack of dyno sheets from previous car tunes that speak to that. You are either in that camp or you aren't, so keep running your 87 if you want, it clearly is the right choice for you, but not sure why people want to dismiss that maybe there is a difference, maybe it matters to someone else, and so let me see if I can make time to run across the state to my usual dyno, I'd do it just to not have to see all the rebuttals anymore even though I really have no intent of tuning this car right now with everything else I have going on in life.
Fully agree with what you say regarding Hyundai, the spread of full N and N Line models is a great thing to see, especially since they offer a lower price point of entry vs the luxury competitors. I am a huge fan of the performance for the price, along with the warranty/reliability of a boring car. If you get a chance to take it to the track, let us all know your thoughts. I have limited track time, just a multi day program running CTS-Vs at the old Bondurant School of High Performance driving, which was a blast. Never have had a car that was track worthy as my own but have had the opportunity to drive a few high power performance cars.

I guess my point was chasing tenths on the street seems like a fun thing to do on paper but with so many factors in conditions, driver, etc that unless it was a big difference, like was shown in the F-150 example above, it probably isn't noticeable to most. You are clearly stating you are in the likely less than 1% that tracks a car, (just like the small fraction of 4x4 owners who go off road, etc) so that is good for the rest of us who will never seek out a tuner or otherwise really enhance the car much beyond stock. For that I would say, if you think there is a benefit (and below I give us some additional hope that it is), then go for it. I will probably now fill up with Shell 93 next time just to see for myself, test out the butt dyno.

I agree that it seems weird that they chose to be very vague regarding fuel type to be used but I bet that comes back to the issues they have gotten into in the past with mpg claims being off, engine recalls, etc. If we all find out that there is some free horsepower locked away, good for us, but they are not going out on a limb to state it so we can't go after them if someone puts it on the dyno and the numbers don't add up. I was initially more worried about making sure the min 87 is not just good enough, but what is healthy for the car. After nearly 12k miles, from low teen temps to commuting in stop and go 100 degree weather and not totally babying it, I can't say I have noticed any issues running 87.

The best guess we can make and I think was brought up in previous threads, absent the dyno results, is that the engine should make 10 more HP using premium grade fuel vs 87, no additional torque. Will have to test this to see if the additional HP but no additional torque (unless it comes on earlier) makes any difference. My guess would be 0-60 remain unchanged, mainly due to just getting power to the ground but the top end, in a 0-100 mph or quarter mile run would probably see a small advantage vs 87. The same engine is used in the Genesis G80 2.5T RWD/AWD and Stinger 2.5T. Both of those vehicles list that this is only achievable on premium fuel, as seen in the screen shots below. All of this could just boil down to a typical Camaro vs Corvette type marketing situation (SS could never make more power than a 'Vette due to it being a "lesser" vehicle in the family tree), corporate doesn't want Genesis (or the slightly more premium Kia Stinger vs the slightly less expensive K5 GT) be shown up by the Sonata N Line/K5 GT with the same engine.

I just filled with Shell 87 last night, will wait a week and refill with Shell 93 when I typically do, with 30-60 miles left in the range.

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Speaking of 93 octane pump gas ...

I was hoping that someone who has purchased a JB4 tuner for there N-Line would post the dyno HP results using 93 pump gas without the JB4 (baseline) .. and with the JB4 MAP 2 (93 octane setting).

There was a dyno sheet on the Burger Motorsports website, but it was without the tuner (baseline) and with the JB4 MAP 1 (91 octane setting), but nothing as far as using the MAP 2 setting.
 
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