Super Unleaded test compared to Regular Unleaded:

[FastDEW1]

I don't accept that on these naturally aspirated engines it makes much difference. Especially with the ethanol method used to bump octane as is often the case (certainly in California). I would like to see some actual full range dyno curves mapped against measures timing maps on the engine using both fuels under same environmental conditions.

 

[Gunkk]

MrBrady: try the TCU "learning mode" reset procedure. From a stop, put in manual, accelerate then decelerate shifting from stop-1-2-3-4-5-4-3-2-1-stop. Then see if you "feel" anything different.

 

[Midnightsun]

Testing with various blends are skewed due to different ethanol content. We all know that ethanol severely impacts fuel economy and the less the better. If go to Shell here in Canada it is written on the pumps. Regular, contains 10% ethanol. Mid grade, contains 5% ethanol. Premium, contains no ethanol. It's more the no ethanol in this case that would definitely improve the MPG. Best bet economic wise is if you can find regular with no ethanol then gas there.

 

[MrBrady]

MrBrady: try the TCU "learning mode" reset procedure. From a stop, put in manual, accelerate then decelerate shifting from stop-1-2-3-4-5-4-3-2-1-stop. Then see if you "feel" anything different.

I'll try that. Thanks.

 

[DRS]

Testing with various blends are skewed due to different ethanol content. We all know that ethanol severely impacts fuel economy and the less the better. If go to Shell here in Canada it is written on the pumps. Regular, contains 10% ethanol. Mid grade, contains 5% ethanol. Premium, contains no ethanol. It's more the no ethanol in this case that would definitely improve the MPG. Best bet economic wise is if you can find regular with no ethanol then gas there.

+1

 

[ppern]

anyone know with the 3.8 v6 if you use regular gas are you getting the full 311hp?

 

[Boulderado]

anyone know with the 3.8 v6 if you use regular gas are you getting the full 311hp?

yes, according to the window sticker 3.8 V6 produces 311 hp on regular gas.

 

[MrBrady]

I believe what you observed. For those who talk only 9 HP lost, it is related to much more than that. The entire power band is affected. And typically much more than a published spec. It has to respond instantaneous to the knocking, hard core. Especially if conditions of the air are not perfect for published spec measuring ( sea level, 29.98, 58 degrees, and 40% humidity or so). In some weather conditions, power across the curve can be increased beyond published spec by the programming (or forced to detune much more). The affect on the overall power band is much more than 9 HP at peak. You will feel the difference, as you have observed. And it will take some time to get the system set up back to the condition because it is set to adapt back slower.

As for the comments for those sniping from under the bridge about torque steer, I understand what you are saying. I assume you meant having to correct the wheel to keep it straight. Enough breakaway power in the power curve to cause the tires to supersede for a short time the nanny ESC. And kinda funny, because of the bushings and no rigid collars in the subframe/suspension mounts, the rear suspension May in fact "steer" a bit from intended line under certain torque related conditions. [emoji41]

In the old days, a engineer acquaintance at Ford had print outs of different graphs and curves for power at different conditions and fuel. He studied them for his autocross weekends we both competed. He would use them in a kinda secret way to understand how much toluene to sneak into the gas. He claimed toluene was like hooking up a O2 tank to the car. Giving it stronger O2 in combustion process. Generating more potential power with right CPU settings. And he would reset/program the CPU in the stock class car. Plus crank up the boost in a custom chassis modified class turbo car. He wanted to help me use toluene to pick up some extra power. I was too chicken to try.. Through him I learned about how the mapping works in general, and how different quality fuels affect how the CPU can help create power with higher octane (and in his case adding things that created stronger explosion in the cylinder, and the effects of higher lead free 100 aviation gas to those additives.. Verses lower octane).

That was in a time that compared to today, the computers and sensors were much more limited. With a high compression engine, adjustable cam timing that have aggressive limits, spark, GDI, and much more, available on the TAU ( and much better/faster CPUs and programming), what is possible today to detune (87 octane) high performance engines (conversely increase performance with optimal fuel) would be so much better.

It is asked above if the V6 is set up where 91-93 under 5% ethanol rating would help the HP curves. That is a question to Hyundai. In general, the V6 GDI has some nice and high compression. They would have to answer if the CPU, cam systems, and other things could take advantage of higher octane. In general publications I have not seen where they say it is optimal or designed to run with premium. I bet in some weather conditions, it could help IF the CPU mappings were designed to react quick enough to capture a advantage of some temporary weather condition. (Low altitude Ultra cold and dry as one example).

Right on the money. Torque steer may not have been the correct term, but yes, that's what I was feeling.

 

[FastDEW1]

So - I have changed over to 91 Octane from 87. I did this for the last 1400 miles. I have run only Mobil 91 (best we can get here in CA). My mileage has not changed at all. I do think the engine seems to be a little more responsive, however it wasn't unresponsive before. It is a little more linear on the power, but not enough to make me want the 91 over 87. The MPG hasn't moved from where its been.

 

[DRS]

So - I have changed over to 91 Octane from 87. I did this for the last 1400 miles. I have run only Mobil 91 (best we can get here in CA). My mileage has not changed at all. I do think the engine seems to be a little more responsive, however it wasn't unresponsive before. It is a little more linear on the power, but not enough to make me want the 91 over 87. The MPG hasn't moved from where its been.

Sorry to hear that with the "highly oxygenated premium gas", which means in Jerry Brown speak, high levels of ethanol, and other nonsense chemicals that ruins premium gas in California. Guess you are back to regular... Unless you want to further let the computer adjust for a couple more tanks (not taking that would help).

Come on out to Indiana and get some Country Mark Co-Op no ethanol premium gas.

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[DRS]

I am posting this as adjacent example of how engines designed for high octane can take advantage of that to produce more horsepower. Yes, this is a pressurized motor.. Yes, ethanol does not have the BTU content (thus, imagine the fuel usage to get this HP). This engine was designed for high octane. Ethanol is somewhere around 100 or more. Which allowed them to tune the engine not just with more boost, but other tools to produce this massive HP and torque at the real wheels. Running premium with a uber high compression motor like we have, IF the tuning takes advantage of this, will produce more full range HP and torque. And slightly better mileage. Hyundai says their tuning takes advantage of the high compression, variable valve lift/duration, and other tricks in the 5.0. I believe them. I get 30-31 mpg in the 2015 on highway up to 78 mph or so. Bit higher overall with the 2012. With regular, neither gets to 29 mpg. Non ethanol 91, and Shell or BP 93 are the same.

Anyway one looks at it, cool article below. And when the road to the turbos is all but set for Hyundai, they ought to take the time to equip their turbos with E85 capability out of the factory. And have built in CPU boost to add 100hp or more at the rear wheels. Sure, fuel economy will tank when someone wants to go red blooded male, or Danica female running E85, but EPA domestic terrorists do not look at that for their dictates. And Hyundai could make any wheezing UPS truck sounding 6 be quiet and smooth (like they take the V8 and keep it quiet). That way, maybe us V8 guys might go for a TT V6 with "instant factory tune E85" HP of say 585 for the 3.0-3.8 TT. E85 is easy to find, cheap enough for this kind of "fun day" driving. Whoever figures this out first will get some loyalty points.. And sell more cars.

I found this story in the Motor Authority iPad app:

Hellcat Converted To E85 Sees 753 Rear-Wheel Horsepower: Video
In stock form, you already know what the 2015 Dodge Challenger Hellcat is capable of achieving when it comes to power. ...

Hellcat To E85 Sees 753 Rear-Wheel Horsepower: Video

 

[Bernster]

I tried regular for awhile on 5.0. Engine seemed rougher running on cold startup idle. Went to premium and roughness went away.

 

[Alwaysforward]

Update:

We just got back from a long road trip and I thought I would update you all on the amazing gas mileage we got with our 5.0 Genesis.


• 7-4-15
o Total miles per tank = 437.5
o Miles traveled = 422.5
o Average MPH = 65
o E/T (Total Time) = 6:27 hours
o 25.5 MPG Computer / 24.33 MPG Calculated
o In ECO/Sport Mode – Super Unleaded

• 7-1-15
o Total miles per tank = 480
o Miles traveled = 201.6
o Average MPH = 38
o E/T (Total Time) = 5:12 hours
o 24.6 MPG Computer / 22.30 MPG Calculated
o In ECO/Sport Mode – Super Unleaded

• 6-30-15
o Total miles per tank = 494.90
o Miles traveled = 151.90
o Average MPH = 58
o E/T (Total Time) = 2:36 hours
o 27.30 MPG Computer / 25.44 MPG Calculated
o In ECO/Sport Mode – Super Unleaded

• 6-30-15
o Total miles per tank = 400.4
o Miles traveled = 326.40
o Average MPH = 40
o E/T (Total Time) = 7:58 hours
o 22.8 MPG Computer / 21.84 MPG Calculated
o In ECO/Sport Mode – Super Unleaded

• 6-28-15
o Total miles per tank = 471
o Miles traveled = 164
o Average MPH = 71
o E/T (Total Time) = 2:17 hours
o 25.5 MPG Computer / 24.69 MPG Calculated
o In ECO/Sport Mode – Super Unleaded

 

[AuToMoSeS]

sub'd. This is awesome because nobody believes I get better MPG from Premium even though I have the data to back it up.

Keep up the good work!

It's not surprising my 2.0 turbo catch 22 on regular, 24 on premium with 10% alcohol and 27 mpg with the premium alcohol free gas from upstate New York. The real question is why is the EPA intentionally destroying fuel economy and actually increasing carbon. They actually went back and recalculated all of the old mpgs downward to reflect the mileage on the current crap gas.