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Ezekielguy86 06-07-2013 09:26 PM

Fuel Grade Questions
Ok so when I first bought the truck I put Spinx 87 in it and got around 14.5 mpg. I then decided to try out 93 and well got no change. We recent got a ton of new QT stations in my area so I thought I would give them a go. I went with 87 again and got the same numbers but with their 93 I get 15.5 range pretty regular. Now this I was excited about and have keep doing it since.

Now my main question is that this is E10 fuel and thats how all the stations in my area are other than one without having to go out of the way. Would it be worth my while to pay the extra for 93 no ethanol from a no brand station?

I have no issues with what Im using now but if something is better than Im all for that. Thanks for the help.

Excoastie 06-08-2013 07:51 AM

I doubt that the 93 will make much of a difference in the long run, at least without a tuner installed.

Our trucks are designed to run best on 89 octane, but will run just fine on 87 (I've been using 87 90% of the time for 3 yrs now with no issues). I'm sure that someone will correct me, but with the 93, you need either a higher compression engine, or a different air/ fuel ratio to get the most burn out of it. I personally wouldn't spend the extra money.

As for the 10% ethanol, there probably isn't much that you can do about that. I also believe that with a few rare exceptions ALL engines will burn it with no long lasting ill effects. I think it's become pretty much the standard in most of the major brand gas stations.

good luck, and hope I actually helped and didn't provide too much wrong info


Ezekielguy86 06-08-2013 01:05 PM

I do have a tuner

Warthog Fixer 07-24-2013 01:14 PM

Octane serves one purpose, to prevent pinging/knocking actually called "pre-ignition". Higher compression motors, to include supercharged (Turbo'd/Blown), require higher octane to prevent pre-ignition. This isn't to say that there aren't other issues that can affect octane requirements. Elevation for example, higher elevation reduces required octane levels. I personally run 85 octane, but I live/drive at 4500 feet elevation. Computer controlled vehicles skew things a bit as they can control pre-ignition by retarding ignition timing to a certain extent.

So, run the octane the manufacturer recommends. If you've modded your motor to higher compression values, through a variety of means (pistons, heads, supercharging, etc...), use higher octane as required to prevent pre-ignition.

The moral of the story is that higher octane does not translate into higher powered gasoline.

AcadianRam 07-24-2013 02:30 PM

It has been my experience that using the highest octane I can find I can go a little farther so that pays for the bigger cost.

I am soon to be 60 years old and using higher octane in a motor is much better for it, but over time it's better to use the higher stuff. In my Hemi I cannot see myself putting 87 , would you put 87 in a Lamborgini even if the maker said it would work.

I'm probably wrong but I just can't bring myself to put 87 in a Hemi

dodge man 07-24-2013 03:02 PM

Running anything more than 89 octane in a stock late model hemi isn't better for it. If you have a tuner and have advanced the timing, higher octane will help.

Warthog Fixer 07-24-2013 03:12 PM


Originally Posted by AcadianRam (Post 1158010)
... would you put 87 in a Lamborgini even if the maker said it would work.

If I didn't have any pre-ignition problems, in a heart beat!


Originally Posted by dodge man (Post 1158033)
you have a tuner and have advanced the timing, higher octane will help.

Potentially yes, but you're changing the the fuel/spark curves. I still couldn't see 93 octane beeing NEEDED, even with a tuner.

Just my .02

dodge man 07-24-2013 03:25 PM

I have a Challenger that I have a Diablo Predator on it. I had a guy custom tune it on a dyno where they can see the air fuel ratio and tune the car to it. A custom tune doesn't really mean much, he just bumped the timing up a couple of degrees from a stock tune and leaned it out a little bit.

With a Diablo you can record data to a laptop and look back and see different parameters. Two of them that you can log are short term and long term knock. I was getting some short term knock with my tune running 91 octane fuel. I'm sure if I was running 93 octane I would have gotten less or none. I was only getting the knock at the high rpms right before the shift into 4 gear. Short term knock isn't all that bad, I think mine was only pulling about 3 degrees of timing at the most. The problem is if you get a lot of knock, it dumps that into the long term knock which means its pulling timing all the time.

So to answer your question, depending the the tune and the tuner, 93 octane might or might not be needed.

Hermes1 07-24-2013 03:43 PM

The prevailing wisdom is using higher octane than required by the manufacturer is a waste of money. An exception might be with a tuner installed, but not having a tuner I do not know. I understand that using higher octane than required, while a waste of money, would not hurt anything, but I seem to recall reading on this forum under one of the many octane threads, using higher octane can have an ill effect. As mentioned our trucks manual recommend 89 but indicate 87 is ok to use. I have always run the highest octane required or suggested by the manufacturer, so I have run nothing but 89 in my truck.

AcadianRam 07-24-2013 04:15 PM

It's ok to use 87 because the computor adjust for knock and ping. That's like saying my heart skips a few beets if I drink orange juice but my pace maker adjust for that. Or I can drink water and I don't skip any. I'll take the water
But like I have said before I'm used to older engines and these new ones run probably all different

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