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3.8 Fuel - Regular or better?

e.han

Hasn't posted much yet...
26
4
3
Genesis Model Type
2G Genesis Sedan (2015-2016)
The engine management on the 3.8L will not be able to take advantage of higher octane fuel.

You can give it higher octane, but it'll not increase the bhp output.

The 5.0L has an engine management that will take advantage of higher octane fuel. So giving it higher octane fuel will result in marginally higher bhp output.
 

STL_Genesis

Registered Member
30
5
8
Midwest - St. Louis
Genesis Model Type
2G Genesis Sedan (2015-2016)
I was poking around on genesis.com. On this page 2020 Genesis G80 when you click on the links in the PERFORMANCE section you get a note stating "Estimated horsepower based on premium fuel ratings. Use of regular fuel will result in reduced horsepower." On the genesis.com site, this note applies to each engine currently offered - 3.8, 3.3, and 5.0 (image attached). In the manual (image attached), Hyundai did not note the "Improved Vehicle Performance" difference based on fuel when talking about the 3.8, they only mention it for the 5.0.

After doing some searching and reading on this forum I see many have thoughts and some serious passion on this topic. According to Genesis (website note), the 3.8 on 87 octane, appears to not be 311hp engine. I would think that average owner would assume that 87 being recommend fuel connect to the stated 311 HP number if they did not see this notation in the various places it is published (typically in mouse type). While the use of 87 octane is great ... I am just wondering to what degree the 3.8 and the other engines are able to take advantage of higher octane. Whatever the answer, I don't think I would be able to notice a change to the driving experience, more just interested in knowing the real numbers.
 

Attachments

EdP

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113
Parrish, FL
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TinsleyC

Registered Member
551
194
43
Dallas, TX
Genesis Model Type
Genesis G80
My guess is that the asterisk on the 3.8 engine graphic was an oversight. The owner's manual seems to confirm that.

It makes sense the 3.3 and 5.0 would perform better on 91+ octane fuel.

I think the 3.8 is correctly rated at 311 HP with 87. I'm happy to have that horsepower in regular fuel. STL, like you, I was curious when I bought the car and that's why I started this thread.
 

pulsar

SUSTAINING MEMBER
388
310
63
DFW
Genesis Model Type
Genesis G70
My wife’s CX9 with turbo specifically states to get the full 250hp you must use premium. Regular yields you about 227hp. I could see Genesis being similar with their numbers. The computer dials the car back slightly. She runs mid grade as do I in my G70 3.3. Can I tell a difference in either of our cars based on fuel, no.
 

STL_Genesis

Registered Member
30
5
8
Midwest - St. Louis
Genesis Model Type
2G Genesis Sedan (2015-2016)
I don't know what you mean that the 3.8 is NOT the 311 hp engine.

There is a definite difference if I fill up using 93 octane. When done, my wallet is about $10 thinner. Car drives the same.

When I stated, "the 3.8 on 87 octane, appears to not be 311hp engine" I was connecting the engine output directly to the octane rating, meaning the engine must be a 311hp engine when fueled by "Premium" fuel with an octane rating matching that used in the benchmark testing performed by Hyundai. Further, as I am sure you know, the numbers associated with "Premium" octane ratings are often in a range 91–94 (or more Octane rating - Wikipedia). The "Premium" fuel designation is fuzzy, one could infer:

A. The 3.8 engine running on 91 octane results in 311hp
B. The 3.8 engine running on 94 octane results in 311hp

Can both A and B be correct? In the above two instances, I would be inclined to think it is one or the other, not both.
 

EdP

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113
Parrish, FL
Genesis Model Type
Genesis G80

EdP

Supporting Member
SUPPORTING MEMBER
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6,556
3,120
113
Parrish, FL
Genesis Model Type
Genesis G80

PMCErnie

Been here a long time....
3,888
310
83
Richmond, VA
Genesis Model Type
1G Genesis Sedan (2009-2014)
I'd not be surprised if it was detuned to suit new EPA ratings.
I doubt the Gen 2 3.8 gets any/much better mileage than the Gen 1. Maybe somebody wants to look it up?
______________________________
 

EdP

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6,556
3,120
113
Parrish, FL
Genesis Model Type
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Kraig Wilkinson

SUSTAINING MEMBER
698
173
43
New Jersey now live in South Dakota
Genesis Model Type
2G Genesis Sedan (2015-2016)

BobBeau

Registered Member
30
6
8
Louisiana
Genesis Model Type
2G Genesis Sedan (2015-2016)
I run non ethanol in everything I own, I believe my Genny runs better on it. I average 28mpg with 5.0 sometimes it goes up to 34mpg believe it or not! Of course that is no red lights or stop signs. Love my Genny!!
I don't even get that in my 3.8 driving it like Morgan Freeman.
______________________________
 

Don88

♪I'll Take You There♫ Staple Singers My G80 Tune
SUPPORTING MEMBER
280
67
28
Vancouver WA U.S.
Genesis Model Type
Genesis G80
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