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Turns out 'recommended' Premium gas doesn't do much

VegasStinger

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#1
Interesting article. This may even apply to the Kia Stinger since it's only recommended to use Premium. You'll give up a little bit of performance but for commuters this maybe something to think about.
http://money.cnn.com/2017/12/12/autos/aaa-premium-gas-study/index.html

On average, the vehicles got 2.7% better fuel economy when running Premium gas. But that's just an average. The results varied from a 7.1% improvement in the big Escalade SUV to a 1% decrease in fuel economy in the small Audi A3.

That means fuel savings are not enough to offset the cost difference between Regular and Premium gas.


AAA also looked at horsepower output. On average, vehicles produced 1.4% more horsepower using Premium. It made the biggest difference in the V8-powered Mustang GT, which generated 3.2% more power using Premium. But the Jeep Renegade actually produced slightly less power when running on Premium.
 
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#2
Another reason I like the Stinger. Premium is recommended in both the 2.0T and 3.3TT. You can use regular :)
 

TurboTx

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#3
I personally wouldn't skip premium in a turbo. My current car, which thankfully goes bye-bye this Saturday, is tuned for both but loses SO much power on regular it could get smoked by a civic. I think the deficit is like 10-13%.

I doubt the stinger GT will be seriously affected by using regular, even if it's a 10% drop you're still putting down over 300 hp, but a drop that big in the base Stinger would put you in the low 200s. That's a lot of weight for 200+ hp to pull around.
 

KiaFan

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#4
I agree with [MENTION=48]TurboTx[/MENTION], to me the gas savings is not worth the power loss even if it's minimal. Would be interesting if someone did some dyno pulls with both gas.
 

Stingin' Away

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#5
I have only noticed a significant difference when it comes to cold starts. 87 causes choppy idle (not the good kind) and its rough. 91 is the highest we have in Rapid and it makes a noticeable difference on startup. My "butt" dyno can't tell the difference WOT and I think there is a slight increase in MPG. It's worth the extra 30 cents or so for premium. I like peace-of-mind.
 
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#6
My recollection is that most modern engines can detect the octane of the gas being used and adjust the engine's timing accordingly. I believe that to accommodate lower octane fuel, the engine's timing is retarded to prevent pinging and this reduces the engine's power output.
 
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#7
My recollection is that most modern engines can detect the octane of the gas being used and adjust the engine's timing accordingly. I believe that to accommodate lower octane fuel, the engine's timing is retarded to prevent pinging and this reduces the engine's power output.
Very true. You won't get full horse power or efficiency but the engine will adjust itself.
 
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#8
With today's high compression, direct injection, forced induction engines I would stay with premium. My F150 with the Ecoboost runs so much better with 93 vs. 87. It will run on 87 but there's a noticeable difference in performance, fuel economy and in smoothness, especially at idle.
 

cobrajet7

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#9
I'd do 91 in summer and 87 in winter. Summers are 105 plus

Sent from my Pixel 2 XL using Tapatalk
 
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#10
Right, it's not about fuel economy nor fuel efficiency. It's about how the engine was designed and the ECU tuned.

OEMs know some people will put anything that vaguely smells like gas in the tank so they try to protect the engines. Some do it better than others. Too low of octane for a particular engine (note that "too low" is a dynamic thing - depends on a huge variety of factors including the combustion chamber pressure (which is much higher with FI engines) and temp at each moment, spark plug temp, exhaust valve temp, etc etc) will result in the ECU retarding timing. Some handle this more gracefully than others. E.g., my '02 Lincoln simply cannot pull enough timing to run reliably on <91 octane, so it'll have detonation which will destroy rod bearings.

Best case, the ECU pulls enough timing to prevent detonation. It'll constantly be in "Oh Shit" mode and you'll be leaving power on the table. Worst case, the ECU can't keep up with the changing dynamics and you end up with rough running, detonation, and unhappy endings.

The good news is the Stinger ECU is super agressive about adjusting timing. They actually use timing adjustment to modify power output - timing advance drops to about 0degrees during shifts to be nice to the trans. So it's likely to be just fine running on the cheapest of gas, but the ECU will likely mess up from time to time and try to get back to its baseline tune, realize the engine is rattling apart, and back off again. Especially when flooring it.

Note that detonation/ping is different than it was in the '70s. We relied on the "metal can of rattling marbles" sound to tune ignition curves, but by the time you hear the marbles the problem is already extremely bad. Modern systems use a knock sensor and apply rather advanced signal processing to it (it's literally a wound wire that vibrates) to determine when detonation occurs. Note that different ECUs have different signal processors and algorithms. Ford ECUs from the late 90's were awful at this, so most tuners turn off the factory knock sensors.
 
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#11
Hmm you are right it is recommended I thought it was required. My wife has the same stinger 3.3 and doesn't ever hit the gas hard so I'm definitely going to start putting regular in that one.
 
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#12
Saving the cost of one Starbucks coffee and putting lower octane fuel in your Stinger is crazy. Make your coffee at home and make your performance engine happy and live longer.
If saving money on fuel is so important the car car you should own is a Camry or a nice boring family car. Just saying.
 
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#13
The OP's article relays documented test results.

Comments about "10% power loss", "the cost of a cup of coffee", etc., are just emotional responses.

Show me the hard data, otherwise, the tests 1.4% average hp increase means we're losing 3-5 hp.
 
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#14
People will sit in line for 10 minutes to buy a $5 Latte or some fancy drink but worry about spending the extra $1 or 2 for the right fuel for their cars. The car that most make a large payment towards each month.
Personal choice but not logical to me. IMHO
 
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#15
Fact: If a Stinger GT owner averages ~22 mpg and drives 15,000 miles a year, he's using 682 gallons.

Fact: Reg fuel in my area costs $2.51/gallon, Premium $3.19/gallon. A difference of .68 cents/gallon.

Fact: That means I'd be paying an additional $464/year to get 3-5 more hp.

Fact: Even if I did buy a fancy schmancy coffee (I don't) it would offer something substantial above a regular coffee.

Another 3-5 hp is not substantial on a 365 hp car. Not even moderately so. But people can do what they want, it's their car.

Just saying ...
 
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#16
@KIA-StingerGT, if you're going to claim facts, then we must do so. However, claiming the average performance increase in that test as the equivalent performance gain for the Stinger GT is a fallacy. Furthermore, the article does not denote how they obtained those increases/decreases in performance. Are they strapping those cars to a chassis dyno, running 87 octane, then draining the fuel system, adding 93 octane and re-running the dyno? I highly doubt it.

Tuners can see when the ECU is pulling timing. Enough of them have done so with this platform to merit a different map just for 93 octane. Granted, they are doing so to maximize the efficiency of the engine beyond the factory setting.
 
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#17
@Stiletto, I thought you said you were going to adhere to reality. Alternately, saying the average performance increase in that test is not indicative of Stinger performance gains is a misdirection. Furthermore, the article used vehicles of different types/makes. Are the across the board results void if the American Auomobile Association didn't explain everything in their test? I wouldn't say so.

The ECU can see when timing needs to be pulled. Enough cars have had this capability for, oh, decades now. Admittedly, manufacturers know how to protect their factory warranty.
 
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#18
@Stiletto, I thought you said you were going to adhere to reality. Alternately, saying the average performance increase in that test is not indicative of Stinger performance gains is a misdirection. Furthermore, the article used vehicles of different types/makes. Are the across the board results void if the American Auomobile Association didn't explain everything in their test? I wouldn't say so.

The ECU can see when timing needs to be pulled. Enough cars have had this capability for, oh, decades now. Admittedly, manufacturers know how to protect their factory warranty.
I never used the word reality.

Misdirection? I didn't discuss anything outside of the topic, e.g. infotainment, tire size, Busch Gardens. Nor was my statement a red herring.

Absolutely the AAA results are void if they did not use something remotely similar to scientific method to obtain the results. I mentioned a dyno, but they could have used other measuring platforms. Even still, I wouldn't apply those results to the Stinger...it's a completely different engine strapped to a different transmission housed in a vastly different chassis and body.
 
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#19
This is a common topic in most performance car forums I’ve experienced. The compression ratio in both the US spec. 2.0L and 3.3L engines is a very conservative 10:1. Because it has direct injection and modern engine controls, damage from detonation and/or pre-ignition with 87 octane would be extremely unlikely…arguably nearly impossible in stock form.

By way of comparison, BMW is using 11:0 compression ratio in their twin turbo 3.0L powering many of their late model products. Higher compression means it has slightly better brake specific fuel consumption than the stinger, and more power per liter, but PREMIUM FUEL BECOMES MANADATORY. The Audi equivalent products are the same way.

Kia seems to understand their market for this car well by giving us flexibility. Audi and BMW do not. This is a competitive advantage.
I am running 87 octane with no drama (1.5 years and 14,000 miles). I’ve experimented with 89 and 93. My results mimic the AAA premium gas study exactly. After geeking out for a few weeks with checking my commuting MPG as a function of octane, I could not detect a meaningful difference. Ditto for any change in perceived power.

If you are running aftermarket tunes (BMS, Lap3 etc.) with more aggressive timing tables and boost curves, then 93 octane is probably a smart idea given the unvalidated operation of the engine under these conditions. It’s pretty cheap insurance. If you are stock, 87 will be fine and aligns with recommendations from my dealership as well.
 
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#20
Excellent post Turbocom, good to see common sense and reason still exists.(y)

The only legitimate data from the manufacturer is that we might lose a few hp/mpg, that's it.

KIA "recommends" Premium Fuel (91 in the US), which is not even remotely the same thing as "Requiring Premium Fuel."
 

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