As far as premium vs regular gas goes...

[RockTheShazbot]

I was bored and looking at the Chevy Volt which has the same gasoline engine as the Turbo Sonic minus the turbo and it says premium required, while the Sonic says Regular. I personally have done a lot of research and am sticking with premium, but for those that might be on the fence, this might help you decide. If you click on the tab that says "All" and look at On-board generator/engine it shows premium only in there.

2012 Chevy Volt Electric Car Features and Specs | Chevrolet

 

[Sonic]

I personally will use premium also. I've never felt comfortable using regular in any forced induction car.

 

[bryandrews78]

The Reason for premium on the VOLT is because the VOLT is built to store gas in the car for a longer period of time. The entire fuel system in the VOLT is a sealed unit from outside air. Since gas loses it octane over time, they use premium in the VOLT because if the fuel sits in the system for over a year it will still have a usable octane rating. The sonic can run on regular just like the Cruze because that is what it is tuned for. The fact that they share the same engine is irreverent because the premium in the VOLT like I said is used for a different reason then it would be used in the Sonic. I talked to my Mechanic about using premium on the Cruze and he said it would be a waste of my money on the stock setup, because those engines are tuned to run on regular and the plugs are not set up to run on premium.

 

[AxelRipper]

Coming from inside GM Powertrain here. Not sure about the gas sitting over time, but it sounds possible. I know that premium is used to help with the economy of the Volt as well. And the 1.4T will run as well or better on premium as it will on 87. Up to you to see if you can tell any difference in power and economy, but it is there somewhat. The engines are tuned for both fuels, and can actively change their tune for differing octane values. I can't say which is better since mine hasn't come in yet so I cant test it out, but the engines will run at their "optimal" for whatever fuel you put in them.

 

[2>4]

...the 1.4T will run as well or better on premium as it will on 87. Up to you to see if you can tell any difference in power and economy, but it is there somewhat. The engines are tuned for both fuels, and can actively change their tune for differing octane values. I can't say which is better since mine hasn't come in yet so I cant test it out, but the engines will run at their "optimal" for whatever fuel you put in them.

So does the turbo deal with lower octane by utilizing a knock sensor and ignition retard? What is the difference in horsepower/torque output with the 1.4 running on 87 vs 91 octane? I guess what I'm getting at is how much performance do you lose using the less expensive fuel. If there's, say, a 5% reduction in performance/gas mileage by using fuel that costs 10% less then the 1.4 seems like a great deal. If there's a 20% loss (not likely, I know, but for the sake of argument) then the 1.8 starts looking more attractive...

Got numbers?

 

[Sonic]

Someone will have to do dyno pulls with one octane, then drain and use the other octane to test that.

 

[RockTheShazbot]

In the research I have done I found out that premium won't really result in more power, some people get better fuel economy, anywhere from 2-10 MPG but that also depends on driving habits. The biggest reason is I heard it helps with engine life and reliability.

 

[Rand0m0sityxX]

I would probably use premium in the 1.4. Stock or not it is a turbo. And honestly when your getting 40mpg, paying the extra 20 cents isn't a lot.

My mom drives a F-150, her's is the v8 triton and requires premium, she won't use it, she runs regular (which she still can't afford in her truck) because premium is too much, but when I get in her truck, I can hear/feel the difference between them. She won't listen to me tho.

Someone could do a dyno on them and see how they are, get some numbers with them both in the motor.

 

[laborsmith]

Cruzetalk has an incredible amount of information on this, many different threads and some include dyno charts. It appears the engine is set up to adjust timing according to the grade of gas, which has an effect on both power and MPG. This is because the engine is used around the world and various areas have varying fuels. I personally would use premium in a forced induction engine, for reasons of longevity as above stated. Anyways, there is a wealth of info, lots of it deals with tuning, but much explicitly with regular vs. premium. Usually using premium when regular is called for is not a best practice, but because of the unique qualities of the 1.4T this may be the exception.

Laborsmith

 

[TravsSonic]

and i can tell you.. its a hair bit more peppy on 104 race fuel.. haha

 

[pawntec]

honestly does anybody know the difference when raising to the higher octane? lol all an higher octane does is that the fuel just burns longer then a lower octane fuel. (i'm not sure the rates are per raising the octane to burn time) so if the motor was tuned to a lower octane and then using an higher octane it's pointless(unless having switched fuel maps for higher octane fuel) and would just add more carbon build up(do to more unburned fuel do to tuned to a lower octane). now with using an lower octane then what the motor is tuned for the ecu would just adjust to using an lower octane from it's sensors and wont have as much power then the higher octane the motor is tuned for and like what bryandrews78 said about the plugs because the temperature of the plugs might not be hot enough if using higher octane then tuned for which equals more carbon build up again.

 

[AxelRipper]

When you add higher octane, the engine will add more spark advance because the fuel is more resistant to knock. On older engines, it was futile to run above the recommended octane because yes, the plugs weren't hot enough, and nothing in the calibration changed, AKA it was tuned for a certain level of fuel and that octane level was "required." Some engines still do require a level of fuel generally to reach desired power/economy numbers but the engine won't die if you put cheap gas in (there are alot of dumb people out there who if they drove your Corvette and didn't know, they'd still try to put 85 in it). Using knock sensors, the engine determines where it needs to have its spark mapping and "optimizes" for whatever octane you're giving it.

After I get mine and get a break in period, I plan to test out some different fuels on the butt dyno/MPG gauge... theres a Valero on my way to work with 110

 

[TravsSonic]

When you add higher octane, the engine will add more spark advance because the fuel is more resistant to knock. On older engines, it was futile to run above the recommended octane because yes, the plugs weren't hot enough, and nothing in the calibration changed, AKA it was tuned for a certain level of fuel and that octane level was "required." Some engines still do require a level of fuel generally to reach desired power/economy numbers but the engine won't die if you put cheap gas in (there are alot of dumb people out there who if they drove your Corvette and didn't know, they'd still try to put 85 in it). Using knock sensors, the engine determines where it needs to have its spark mapping and "optimizes" for whatever octane you're giving it.

After I get mine and get a break in period, I plan to test out some different fuels on the butt dyno/MPG gauge... theres a Valero on my way to work with 110

110 at a valero? only 110 i've ever seen was E85, and you don't want that.
104 race fuel that is still street-able from sunoco is the highest i've seen

 

[AxelRipper]

110 at a valero? only 110 i've ever seen was E85, and you don't want that.
104 race fuel that is still street-able from sunoco is the highest i've seen

Thats what their sign says... its near a few lakes so I wouldnt be surprised.

 

[TravsSonic]

oh yeah.. boats...

 

[wickedsonic]

As axelripper said, the timing changes ( to an extent) based on knock signal (or lack thereof) from the knock sensor. Now if the car needs 25 degrees of advanced timing and you can do 50 degrees with 91 octane, the cars still going to do 25 degrees and thats biased per logic block in the ecm.
Everyone also needs to realize fuel quality and ethanol contant is different everywhere in the u.s. so as you guys debate dont forget that what works in florida for guy a at elevation 100ft isnt the best for guy c in colorado at 1400ft of elevation. The car ecm has a big enough adaptive range that the cars can run correctly, and efficiently, in all u.s. situations without running you off on the side of the road.

I'm a automotive techology instructor and when i did a review with my students doing multiple octane situations and keeping driving the same, 7 out of 8 students in that engine performance class all got better gas mileage on premium then 87 however not enough to warrant the 20 cent difference per gallon in cost.

If you want to know for sure, you need to run your car down the track and datalog spark advance under both situations and see which one peaks the highest timing but remember it will only go so far . Its not like 300degrees of advanced timing is beneficial

 

[ronarn]

reg vs 110 octain

i use jet fuel in all my cars but never seem to get off the ground. don't know if it's me or the spark that's retarded

 

[RockTheShazbot]

i use jet fuel in all my cars but never seem to get off the ground. Don't know if it's me or the spark that's retarded

hahahahahahah

 

[ronarn]

jet fuel or rocket fuel?

my dealer advised me not to use either but if i needed more thrust than i was getting with reg he would be happy to put a stick of dynamite in me and light the fuse himself to get me out of the service dept.