Octane Issue

[BigsViper]

Since day one (3 months ago) I have used Shell 93 octane super premium, as Shell is the only station in town to sell 93 octane as specified in the manual for my 2000 GTS.

Last week I had a coupon for a few bucks off of a tank of Fina super unleaded, and I decided to give it a try, but it is only 92 octane. I noticed that the car didn't seem as strong with this fuel, and since I have had it in there it is very sluggish starting. Before this tankful you just touch the start position with the key and it fired up, now it chugs and feels like an extremely cold start, even though it has been warm here and the car is always garaged.

Am I nuts? I wouldn't have thought 1 octane would make any difference.

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[FRANK]

I think you might have bought some crappy gas or you are just imagining things. The Viper should run the same regardless of what octane as long as it is 91 to 93...

If you stated that you put 87 in there...then you may have been right in your assumptions.

 

[Bob Woodhouse]

There are much more sophisticated answers to your question but a couple of things to remember. Octane does not increase power. Octane will subdue detonation. If you had no detonation, which I doubt you did, then you would not have any difference from it. You could have fuel that is much lower in quality as suggested however. One measure of comparative power from fuel is the specific gravity, which varies a lot. If you are evaluating engine power on a dyno, one of the things that should be known are the specifics of the fuel which will influence the power output.

 

[Chuck 98 RT/10]

Stay with Amoco if you can.

 

[BigsViper]

No Amoco retailers in West Texas.

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Will go back to Shell 93 and be hard pressed to change again!!

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[Supercharged Vipermad]

Frank, please dont **** out your Viper with crappy stuff like you said you were going to install.. Are you one of those guys with the cheesy fuzz ball on window????

 

[Frank 03SRT]

Looks like FRANK left the cheezy fluff ball off his signature. Wish he would put it on there. It's worth at least 1HP.

 

[garolittle]

I have put Shell 93 Octane in my '94 RT/10 and have been pleased with the results. Stick with the Shell guys.

 

[BigsViper]

Thanks for the input! Venomuus, I guess you missed the great thread awhile back which would give you the history of Frank's sig mods (and some

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and some tense moments

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). For your reading enjoyment I have posted the link to this thread, although I'm sure there are many who would have preferred to let it die! http://64.70.135.137/ViperUBB/Forum17/HTML/000281.html

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[JonB]

Some other 'coincidence' is involved beyond the 92-93 octane. LikE FRANK said, 91-93 should be irrelevent.

Perhaps the 92 Fina is 'oxygenated' with alcohol for wintertime, and the Shell is in a diffrent county, and not Oxy? Your 'adaptive ECU' may sense something different.

You probably DId get the dregs of an in-ground-tank of Fina Super...maybe they were having a coupon sale for a reason!

I would add Shell 93 ASAP and maybe a can of Alcohol-based Octane Booster {Alcohol absorbs any water) ONLY if the situation does not correct itself w/ 1-tank of Shell.

I NEVER suggest cheepie alcohol-based octane boosters unless ONCE ONLY as a 'cleaner'

JonB