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anyone using premium gas ?

1M views 2K replies 423 participants last post by  paulrondelli 
#1 ·
yes or not worth it
 
#134 ·
I just put in 93 yesterday to try it. Felt good. I think I will give it a couple tanks to see mileage/performance differences. Performance is going to be biased since I am installing my intake tonight
 
#135 ·
If your engine is not knocking and/or pinging there will be no difference in using 87 Vs 93 octane. The only thing the higher octane would do is reduce a tendancy for pre-detonation (knocking/pinging). The engine is designed/engineered to use 87, anything more would be a waste of money.
 
#137 ·
So, you're saying that there's no way the ignition can advance more than what is required for 87 octane? I call BS. Even the owners manual states that higher octane will provide improved performance. The Focus wouldn't be a true FFV vehicle if it didn't have that ability.

Sent from my SAMSUNG-SGH-I997 using Tapatalk 2
 
#141 ·
I tried both 92 and 89, and settled on 89. Smoother at low speeds, a little better mileage, and a little more power. The 92 wasn't better than the 89 so I went with the cheaper choice.

I know this is subjective, but I notice a difference.
 
#146 ·
Just wanted to jump in and put some info into this debate. If you look in your owners manual in the "maintenance" section approx page 330ish it says "Some stations offer fuels posted as 'Regular' with an octane rating below 87, particulary in high altitude areas. Fuels with octane levels below 87 are not recommended. Premium fuel WILL provide improved performance."
 
#147 ·
If you look in your owners manual in the "maintenance" section approx page 330ish it says "Some stations offer fuels posted as 'Regular' with an octane rating below 87, particulary in high altitude areas. Fuels with octane levels below 87 are not recommended. Premium fuel WILL provide improved performance."
This was already stated several times in this thread.
 
#149 ·
This really isn't rocket science. The higher the octane, the slower the burn rate. There is no "performance" gained from higher octane fuel. Any engine will run it's best on the lowest octane fuel that can be safely run. If you have a NEED for higher octane, then you will see a gain in performance, but it's from the timing, compression, boost, etc....not the fuel. Higher octane fuel just slows the burn down so that the burn happens a bit later in the cycle. If you have a motor with high cylinder pressures or temps (i.e. boost, high compression) then you need the burn to occur later otherwise you can get detonation.

Nobody with a properly running engine should be legitimately "gaining" fuel mileage or performance from higher octane than factory recommended. If they did, then that particular engine needed it in the first place.
 
#151 ·
So, rather than speculation, the only way to solve this is through dyno testing in both 87 and 93 octane modes, right? I haven't seen that one yet. If I've missed something, please let me know.

FWIW, I've been running 93 for a while now, and I'm averaging a little over 32 MPG in mostly around town driving. One place where I notice a difference is on uphill climbs, where the 93 clearly allows the engine to pull better.
 
#158 ·
So, rather than speculation, the only way to solve this is through dyno testing in both 87 and 93 octane modes, right? I haven't seen that one yet. If I've missed something, please let me know.
Once again for those that missed it, or just didn't watch it. They don't use a Focus, but I believe the Focus has the similar sophisticated engine management, TI-VCT, that the Subaru and the VW have.

http://www.youtube.com/watch?v=gQghB4asSnI
 
#160 ·
The way I read that verbage in the manual, is that it means in areas where regular is considered lower than 87 octane, to use fuels labeled premium for better performance (especially in high altitude areas).
 
#161 ·
There's no right and wrong answer, because every person will have a different experience.

Even with dyno tuning, variations in ambient air temperature and humidity, as well as altitude will affect mileage and performance.

Each person's driving habits are different as well. I've put 8,000 miles on my 2012, I'd guess probably 60% city and 40% highway. I've NEVER seen more than 35mpg, even on trips that were 100% highway, driving with the cruise control set the entire trip.

*I do have a heavy foot, so this is most likely my fault.

I tried 93 octane for 3 tanks of fuel and did NOT notice any improvement over 87.

After that, I switched back to 87 and removed the cover on the air intake.
Despite higher intake air temps, I did see an average gain of about 4mpg over 8 consecutive tanks of 87 octane, as well as better throttle response in the low end. Throttle response is better in the high end also, but not as dramatic a change as in low end. The engine stumbles less now as well, as long as I can get that stupid DCT transmission to downshift appropriately.

Next, I plan on trying another 3 tanks of 93 octane with the cover removed.
 
#174 ·
The fact that the car has a compression ratio of 12:1 would favor higher octane gas. The smarts in modern cars and the ability to dynamically change valve and ignition timing and other parameters as well permit you to use lower octane gas but 12:1 would still prefer higher octane.

I can imagine a dual performance benefit of slightly more power AND slightly better mpg, but just how much better the mpg is I can't say and short of a true scientific series of tests it would be very difficult to see that difference unless the differences is larger than about 5% percent or about 1.75mpg.

I'd put the difference in price between the highest octane gas versus the lowest octane gas to be about 7%, and the difference between mid and high octane being about 4%. So, if the lowest octane is below 87 than the real difference would be between mid and high so roughly 4%. If the improvement in gas mileage is greater than 4% then it would be cheaper to use high octane versus mid octane.

Those of use living in mountain regions usually see the low octane being 85 or less than 87 so we need to go with either mid grade or premium gas.


Brian
 
#180 ·
If you look at the fine print in the latest Taurus SHO commercials it states that to get the full 365 hp you need to run premium fuel. So if ford is programming the PCM on the SHO to sense different octanes and adjust power output accordingly, then they are probably doing it on our focii also.
 
#182 ·
The sho DOES NOT require premium fuel, ford just states in the fine print that to get maximum performance that premium is needed. So by using the same type of programming they can take advantage of the higher static compression in the focii.

Follow me now?
 
#183 ·
Okay - so the SHO has a lower octane requirement, but Ford discloses that higher octane will lead to improved performance? So you're saying that the same may be true for the Focus. Makes sense, except why no fine print stating such?

I don't necessarily disagree with you, but frankly I think any difference in power or mpg is probably pretty negligible, and am inclined to run the recommended 87 octane as long as no knocking or pinging results.
 
#184 ·
I think the reason is that the sho is advertised at 365 hp and you need to run premium to get it, and most sho customers know that they are supposed to get that much. Also you may lose 30-35 hp by running regular fuel in a boosted application and customers would cry foul if they lost that much, so ford has to disclose that info to cover their a$$. Remember the 99 mustang cobra that was advertised at 340 hp but the actual cars never reached that much, ford had to recall all of them and rework the engines to get the claimed power output, they wont do that again.

I also agree that the difference on a 2.0L 4 banger is not much, 5 hp at most. When I had my truck custom tuned on a dyno I got 238 rwhp on 87 and 250 rwhp on 93 only a 12 hp difference on a huge 5.4L V8. Factory tuning is very conservative, the gain on the focii engine is probably closer to 2 hp.
 
#189 ·
For the sceptics: A high compression VVT engine in most cases can and WILL benifit from using higher octane fuel to the point that timing is not retarded due to the variables that many have already discussed. Same concept that all the force-induced guys use all the time. Argue until your blue in the face but facts are facts. Once your timing is optimal, your using the right octane. Another good reason to use higher octane is because most all "Premium" gas has additives that do a world of good for your motor. It definatly wont hurt to use it unless you don't want to shell out the cash for it in which case 87 will do just fine.
 
#196 ·
And the MPG ratings for using E85 are WAY lower than regular gas, so again, no benefit of higher octane.
The ~ 105 octane of E85 is the reason it gets better mileage than what the btu content would suggest. I'm getting in the 33's on E85 and bet 38 would tops for gas the way I've been driving. Haven't hit 1000 miles yet on the odometer. This new Focus and the Buick turbo Regal are the only two cars made that do justice to E85.
 
#198 ·
Sweet jesus I've never seen so much butthurt especially from people who somehow have it in their minds on how to tell others how to spend their money

High octanes will help VVT-DI engines. That is just fact.

Will you notice mileage/performance increases? You might, you might not. Depends on how hard/effienct you drive your car to begin with.

Let people who want 91 or higher (like me) spend our money and continue with what works well. Why get so mad about it.

Until someone takes 2 Focii, one on regular and one on premium for a few thousand miles and gets hard numbers we only have personal subjective opinions to go off of.

No need to piss on each other about it.

The Focus is a 12:1 compression engine. Simple 'how do engines work' knowledge would tell me that a higher compression engine can benefit from better fuel.
 
#199 ·
Sweet jesus I've never seen so much butthurt especially from people who somehow have it in their minds on how to tell others how to spend their money
Preach it!

But seriously, if someone is going to tell us how to spend our money (and no one on FF should), there are much more irresponsible things we could be doing with our money. Moreover, if I use premium (and I have been doing my own testing with mixed results based more on brand/location than octane) and I consistently get better gas mileage with my hand calculations. Well, then they're wrong and I'm saving money.
 
#201 ·
If you guys want this settled. Get a car, and a dyno. Run it almost to E, fill with a gallon or two of regular. Dyno it, then drive it around until it's about to be empty, fill with Premium, re dyno, (same day) and see if there is a gain.
 
#205 ·
I am on my 3rd tank of 89 octane, if the price doesn't keep skyrocketing here in the northwest, I am going to run 92 octane for 3 tanks. The last 2 tanks got me 35 and 34.9, respectively, hopefully the current tank will be consistent.
I also have a station near me that sells non ethanol, and I am going to see how much that costs, if it costs less than the 92, I may try the 87 they have for 3 tanks to compare.
 
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