Premium fuel on a long trip - General Forum

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Premium fuel on a long trip
Thursday, June 09, 2011 6:41 AM
I wanted to know if there was possible advantage or even a disadvantage to using premium fuel on a long trip. Next week I'm driving 750 miles to Ft Lauderdale Florida. I always fill up with regular 87 octane. Just looking for input.

2.4L 5speed.


Thanks






Re: Premium fuel on a long trip
Thursday, June 09, 2011 7:02 AM
Our PCMs have a high octane and low octane table. With that being said. In stock form 89 is the best grade to be used. Anything higher will work fine, but it is not needed. Jeffie and PJ took data-logs of different grades, and 89 was the best bang for the buck on a stock tune.
This are the settings from a stock tune.






Re: Premium fuel on a long trip
Thursday, June 09, 2011 9:21 AM
I was recently looking at my gas receipts, over the last month I did 2 tanks of 87 and 2 of 89.
The average for 87 was 49.257L for 628km (7.84L/100km or 30mpg)
The average for 89 was 46.128L for 700km (6.56L/100km or 35.86mpg)

Both were a mix of city driving and highway driving (105km / 65 miles) going to work and back 6-7 days a week. No I didnt noticed any performance gains, so the question is it worth the extra 5-7 cents per litre? I crunched some numbers and I worked out that 87 is $11.xx /100km, while 89 is $10.xx /100km.

Sorry I have the day off today and got bored lol



Re: Premium fuel on a long trip
Thursday, June 09, 2011 12:34 PM
-MD- Enforcer wrote:

Our PCMs have a high octane and low octane table. With that being said. In stock form 89 is the best grade to be used. Anything higher will work fine, but it is not needed. Jeffie and PJ took data-logs of different grades, and 89 was the best bang for the buck on a stock tune.
This are the settings from a stock tune.


Those timing tables are not really about Octane. It is for our ECU to adjust to knock.



FU Tuning



Re: Premium fuel on a long trip
Thursday, June 09, 2011 8:10 PM
You could just buy 1 can of seafoam for 8-9 bux average and add accordingly.Plus the added cleaning it does in the process.My take



Re: Premium fuel on a long trip
Thursday, June 09, 2011 8:56 PM
hit me up if u roll through albany ga.
Re: Premium fuel on a long trip
Thursday, June 09, 2011 9:24 PM
Screaming for Mercy!! wrote:

Those timing tables are not really about Octane. It is for our ECU to adjust to knock.


Annnnnnnnnd.... octane is a measurement of resistance to detonation, otherwise known as "knock"... so.... ?? that would be precisely what those tables mean.



Re: Premium fuel on a long trip
Friday, June 10, 2011 4:17 AM
John Lenko wrote:

Screaming for Mercy!! wrote:

Those timing tables are not really about Octane. It is for our ECU to adjust to knock.


Annnnnnnnnd.... octane is a measurement of resistance to detonation, otherwise known as "knock"... so.... ?? that would be precisely what those tables mean.


Yeah... but the car is designed to run on 87. So by all means, the only thing that should happen is OP gets more money out of his pocket. Although, it's fair to point out that older, higher mileage engines typically can benefit from a higher octane fuel. I would make a guess that 89 would be probably a good selection but 93 might be overkill.

To the OP's question. Hard tellin. You'd really have to run a couple tanks of regular, and a couple tanks of the other stuff to find out how it works for you. Not really any way to tell what the ups and downs will be via the internets.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Re: Premium fuel on a long trip
Friday, June 10, 2011 8:43 AM
Ron Love wrote:

You could just buy 1 can of seafoam for 8-9 bux average and add accordingly.Plus the added cleaning it does in the process.My take


Actually this was done recently.

Thanks for all the info. What I'm going to do is run 89 octane on my way down and run 93 on the way back. It takes about two full tanks of fuel to get from charlotte to ft lauderdale.





Re: Premium fuel on a long trip
Friday, June 10, 2011 9:44 PM
Daniel Thissen wrote:

I was recently looking at my gas receipts, over the last month I did 2 tanks of 87 and 2 of 89.
The average for 87 was 49.257L for 628km (7.84L/100km or 30mpg)
The average for 89 was 46.128L for 700km (6.56L/100km or 35.86mpg)

Both were a mix of city driving and highway driving (105km / 65 miles) going to work and back 6-7 days a week. No I didnt noticed any performance gains, so the question is it worth the extra 5-7 cents per litre? I crunched some numbers and I worked out that 87 is $11.xx /100km, while 89 is $10.xx /100km.

Sorry I have the day off today and got bored lol


Did anyone read Dan ^^^^ in his post? The 89 was more fuel efficient, thus overall cost less. I think that means the 89 saved him money over the 87, but that's just my brain talking..



Re: Premium fuel on a long trip
Sunday, June 12, 2011 5:03 PM
Thanks John




Re: Premium fuel on a long trip
Sunday, June 12, 2011 8:08 PM
I'm gonna try it. I've got the tank of 87 to finish up first, but then I'll give it a go.



Re: Premium fuel on a long trip
Sunday, June 12, 2011 8:49 PM
octane should have no effect on fuel economy.

all octane is, is a measurement of a fuel's resistance to detonate. The higher the octane, the more resistant the fuel is. if your car isn't tuned for 93, you won't see any benefit from it, therefore the pcm will control the injectors the same, and the same amount of fuel will flow ...

the "i will try this fuel, then that fuel test" has a major flaw... unless you drive your car through the tank identically, you will skew your results... you may drive the car harder or softer and more or less points throughout each tank, which will demand a different amount of fuel to make the power you are currently commanding.

The ONLY reason i run 93 is due to my Pistons, cams, injectors, and tune.



Re: Premium fuel on a long trip
Monday, June 13, 2011 7:39 AM
I will be making the same exact trip down to Florida and back. Same exact roads. In fact its 90% interstate driving so I believe I can control the output. If I keep it at a steady 65 mph I will be able to get some good results.





Re: Premium fuel on a long trip
Monday, June 13, 2011 3:55 PM
Mystic02VA (GME Chat) wrote:

octane should have no effect on fuel economy.


You're right.. it shouldn't. But the PCM will advance timing as far as it can, without getting detonation. Maybe that just happens to give someone the ability to get better fuel economy somehow.

I still don't see how.. but I'm willing to try it over a couple of tanks, just to satisfy my own curiosity!!



Re: Premium fuel on a long trip
Monday, June 13, 2011 7:01 PM
does the PCM just go until it thinks its about to detonate... or is there a set value in a table somewhere ? i thought ignition timing was preset in the tune.



Re: Premium fuel on a long trip
Wednesday, June 15, 2011 4:48 AM
Mystic02VA (GME Chat) wrote:

does the PCM just go until it thinks its about to detonate... or is there a set value in a table somewhere ? i thought ignition timing was preset in the tune.


Like I mentioned in my last reply. Older higher mileage cars tend to benefit from a bit higher octane. My dad told me stories about knocking or pinging. But the truth is that you usually don't hear that on newer cars. I'm sure there's a certain degree set for the timing in the tables, but the PCM will turn back from that if it sees a bit of knock. Which could cause a lower MPG. I don't see it happening on a fairly new car, or even an older car that's been taken care of really well. But, like i mentioned before. It's kinda hard to tell from the internet what's going to happen on Hardcore's car. He's just gonna have to try for himself.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Re: Premium fuel on a long trip
Thursday, June 16, 2011 9:04 PM
First tank of fuel:

373 miles on 87 octane. So about 26 mpg





Re: Premium fuel on a long trip
Friday, June 17, 2011 12:19 AM
only 26 on the highway? did u keep a steady 65mph like you said? seems a bit low



Re: Premium fuel on a long trip
Friday, June 17, 2011 12:21 AM
i take that last comment back relizing you have the 2.4, i was thinking you had the 2.2, although it still seems little lower then i thought.....i heard somewhere every 5 mph over 60 is like paying 10 cents more per gallon....that was when it was 4.50 a gallon



Re: Premium fuel on a long trip
Sunday, June 19, 2011 5:30 PM
my 2.4 always averaged about 30 at 65




Re: Premium fuel on a long trip
Sunday, June 19, 2011 6:09 PM
i average 28 at 75...but it doesnt really make a difference wether I go fast or take it easy...roughly same gas mileage




Re: Premium fuel on a long trip
Tuesday, June 21, 2011 8:33 PM
Umm knock and ping.Well my 26 yr old cavalier does not do this,nor does my 24 yr old mazda truck both run 87 and quiet.Granted I do take da!! good care of both and have redone alot on both.I think the knock and ping applies more to cars made before 1980 and back.Just my take bc of changes in fuel systems,engines etc.And to add some old info my cavalier when I drove it hwy mostly commuted 120 miles daily it averaged 34mpg all day long.It has the 2.0 ohv 4spd manual.Have not checked it in yrs bc I kick around in town mostly same for the truck.



Re: Premium fuel on a long trip
Friday, June 24, 2011 3:33 PM
I guess I should have mentioned I have a check engine light with a code p0420. But this is my conclusion. After using the tank of 87, I filled up with 89. I got terribgle MPG. SOmething like 19 MPG on the highway!! So I decided not to go forward with the test of using 93. Im not sure the p0420 code has alot to do with my poor gas milage. Opinions?





Re: Premium fuel on a long trip
Friday, June 24, 2011 8:06 PM
I just ran a tank of 89 to, and same with me horrible mpg's. Maybe cause I didn't unhook my battery for it to relearn?



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