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higher octane gas?

Maybe. I would like to read the engineer's test methods to think about how this test was conducted. Their article defines top tier as the brand, not octane, in case there is any confusion going back to the thread topic..

Correct, I was addressing the possible benefits of Top Tier fuel. Those would exist no matter what octane the fuel is.
 
All has to do with compression ratios. The G80 5.0 is has a compression ration of 11:1. Any automobile with a compressions ratio of greater than 10:1 included can run and take advantage of the slower burning premium fuels. As we already established along with the cost which is negligible. In most, it's a few dollars more per fill up.

If you want to take advantage of better performance the engine has to offer, you simply use premium fuel.

The carbon build up on the GDI engine valves comes from oil and fuel dilution plain and simple. You're only telling half the story. Unburnt fuel and oil are recycled thru the PCV and emissions system back thru to be re-burned in the combustion chamber. This is where the carbon deposits form on the top of the valves comes. The biggest problem with the GDI engine is keeping the injectors clean. GDI engines have been around for more than two decades and operate fine without major problems or issues.
 
holy wow.....just read every post on this thread because i was bored....now im not a scientist or a chemical engineer by any means but higher octane burns cleaner period. nobody driving any Hyundai (me included) will ever notice a huge difference between 87,91,93 octane fuels, however if you can afford $2 more a fill up go with the good stuff. there is less than absoutley ZERO downside to burning a higher octane even if your most demanding drive is to the local supermarket.

Where do you live that you can fill your tank with premium for only a $2 difference? Here in Miami, there is usually a 60 cents/gallon difference between 87 and 91, which results in a $10-$12 difference per fill-up. That said, I've been putting premium in my tank ever since I purchased my car 5 weeks ago simply because every car I've owned in the past 20 years (Mercedes, Lexus, Maserati, Jaguar) has absolutely required it, and it was just a matter of habit to me.

After just reading this thread, I decided to pull out the manual to my 2019 G80 3.3T Sport and read what Genesis has to say about it. On page F6 of the 2019 manual, it states that for the 3.3 and 3.8 engines, the "vehicle is designed to use only unleaded fuel having an octane number of 87 or higher." Interestingly, there is no mention whatsoever of premium fuel even being recommended for these engines.

Now contrast that with what the manual has to say about the 5.0 engine: "Your new vehicle is designed to use only unleaded fuel having an octane number of 87 or higher. For improved vehicle performance, premium unleaded fuel with an octane number of 91 or higher is recommended."

So, the manufacturer recommends, but does not require, premium fuel for its vehicles with 5.0 engines, but does not even intimate in any way that it should be put it vehicles with 3.3 or 3.8 liter engines. I guess I should have read the manual when I first bought the car, lol.
 
This is what it says for the G70:

5C9E96EB-DA7F-47C3-8DBC-BCDBB67D155B.webp
 
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Seems like the twin turbo will have more power/performance with premium. Is't the main reason you would buy one?
 
With 3.3T and a compression ratio of 10.0.1/premium fuel 91 + is recommended. 5.0 Tau definitely premium at 11.8:1 compression ratio.
 
What is the power difference between regular and premium in the 3.3TT?
 
Not according to my manual its not.

Genesis Newsroom
Genesis Newsroom

The 3.8 and 5.0 are different ratios but the 3.3T is 10.0.1. as noted above on the two Genesis websites. Unless Genesis is lying themselves.:nonono::empathy:

Sorry, Glen there are no statistics for either that I know of. You'd have to put it on a dyno to find out, testing both fuels separately.
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Genesis Newsroom
Genesis Newsroom

The 3.8 and 5.0 are different ratios but the 3.3T is 10.0.1. as noted above on the two Genesis websites. Unless Genesis is lying themselves.:nonono::empathy:

Yeah, I know what the compression is. Did you somehow miss my post above where I quoted exactly what the manual states with respect to the 3.3T engine?
 
Sorry flipped my remarks when I quoted the recommended fuel. Should have read definitely recommended for the 5.0. However, with a 10.0.1 compressions ratio the 3.3T is designed to run its best and take advantage of the slower burning premium fuels. Any engine with a compression ratio of 10.1 + will run better on premium.
 
Have a 2015 3.8 G80. The dealer says that the engine is tuned for 87 and using higher octane will make no difference.
A friend says premium will give me 7 more horsepower, which is no big deal anyway.
Is there any benefit to using higher octane gas in terms of of engine wear or performance?
Yes, high octane gas will give your engine better performance. However, not by much. Maybe about 7-10 horsepower peak and few more miles to the gallon due to running more efficiently. The exact number has not been tested so it is all speculation based on the engine high compression. It all depends on the fuel maps that Hyundai programmed into the ECU. But yes, I believe that premium gas is better for the engine overall. However, someone will claim the opposite.
The best way to find out is try using both gas types long-term and see how the engine feels yourself. It will take a few tanks of using one gas type for the ECU to adjust its parameters to adapt to the knock sensor data and for the gas tank to only have a certain octane without blending the two fuels.
 
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