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Old 12-30-2006, 02:23 AM   #1
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higher octane fuel

Can a higher octane hurt a car (spark plugs) just wondering. I know some people that think they can ho faster and do all this stuff cool amazing stuff (fly, go back in tiime, end world hunger, and fight polio) with that magic 93 octane.
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Old 12-30-2006, 02:46 AM   #2
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seems to boost my top end and give better mileage when driven hard... same 300 mile trip with 87 and 92 got 32 and 35mpg respectively, both were mostly 80 with some sprints to 100... although I was a little more conservative with the 87 it still got worse mileage.
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Old 12-30-2006, 10:40 AM   #3
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If it was any other car I would say that it would hurt mileage and power. For those who don't know, the higher the octane the slower the fuel burns, so basically you want the lowest octane you can get away with for max power.

This car has 10.5:1 compression though. The ecu must set the timing really low to get the car to run on regular gas. You have to wonder how much power is being hidden by the 87 octane tune. You also have to ask yourself if the ecu could adapt to 93 octane and give you more power.

In my old Neon it recommended premium fuel. You could put regular fuel in but mileage and performance would suffer.
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Old 12-30-2006, 04:16 PM   #4
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I have seen a noticeable improvement in mileage jumping to 89 from the 87 octane.
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Old 12-30-2006, 04:21 PM   #5
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Originally Posted by captainzerocool View Post
I have seen a noticeable improvement in mileage jumping to 89 from the 87 octane.
I am going to give 89 a try for the next fill up.
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Old 12-30-2006, 08:25 PM   #6
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I think I am going for an octane upgrade next fill up as well, has anyone tried an octane booster aditive?
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Old 12-30-2006, 08:30 PM   #7
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I think I am going for an octane upgrade next fill up as well, has anyone tried an octane booster aditive?
Don't bother with that junk. Just mix in some higher octane with the regular if you feel the need.
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Old 12-30-2006, 08:32 PM   #8
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I never realy tried an octane booster, just wondering if anyone has...
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Old 12-30-2006, 08:41 PM   #9
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putting additives in your tank can sometime mess up the sending unit. I put a few cap fulls of Marvels Mystery oil into my Neons tank and it read 3/4 after a fill up.
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Old 01-03-2007, 12:19 AM   #10
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I'm not big on fuel additives. I did however get better mileage with 91 (premium here in SD) octane fuel but didn't record the exact numbers.
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Old 01-03-2007, 09:44 AM   #11
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For what it's worth, I paid the extra 20 cents per gallon ($2.00) for super unleaded (91 octane) yesterday. Since our engines have a fairly high compression ratio I figured I'd give it a go and see. Should I disconnect my battery to reset the ECU?
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Old 01-03-2007, 11:44 AM   #12
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Someone put some hard numbers in this thread please. I'd love to know if the MPG increase (whatever it may be) actually offset extra 20 to 35 cents per gallon it would cost to run Super over regular unleaded..

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Old 01-03-2007, 06:48 PM   #13
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Higher octane fuel don't burn slower...in most cases burn rates are the same provding the fuel additives are the same in both octane fuels.... if they do it's because of additives in the fuel, ill get to that later. A higher octane simply means it has a higher flash point meaning it takes more heat and compression to ignite the mixture.
10.5:1 is not a high compression engine and does not require a high octane fuel. Sure it's a bit higher then many cars but many bikes have compression of 12:1 and still run 87 octane. A lot depends on the combustion chamber design, timing and fuel maps.

Octane boosters don’t really bump up the octane of the fuel
Most only 3-7 points witch is less then one octane level. Octane booster do however contain additives the remove or neutralize free radicals in the fuel that promote detonation and pre-ignition.

Because higher octane fuels have a higher flash point; meaning is it takes more heat to ignite. Higher compression creates more heat. So to avoid igniting the a/f charge prematurely you want something that has a higher flash point. If your engine don't have any problems with the engine suffering from detonation or pre-ignition you don't have to worry about using a higher octane fuel. it won't do anything.

Additives or lack of, in the fuel can help to increase or decrease the burn rate slightly as well. Running a higher octane fuel in of itself will not increase HP. This is a myth.
Rule of thumb is only run the amount of octane needed to prevent detonation or pre-ignition of the fuel. Run anything over that and there will be a loss in power as the fuel/air mixture is not able to burn completely.
Black smoke or carbon collecting in the exhaust tip is a sign of a rich mixture and/or the engine not being able to burn all of the fuel completely. Runnning a higher octane then the engine needs or was designed to run can and often will shorten the life of the polution control system (cat convertor and oxygen sensors)

Think about it...why design a econo box if it requires or performs better on the most costly fuels available....
Stick with the 87 or if you are hauling a heavy load or lots of passengers bump up to an 89
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Old 01-03-2007, 09:15 PM   #14
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Interesting read... I wonder if the engines here are tuned differently, as 91 octane is the lowest you can get, as well as 95...
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Old 01-03-2007, 10:21 PM   #15
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duno, better top end and better mileage for me... I don't think the 2-3mpg increase I've seen offsets additional cost.

The manual doesn't say you can't run 93, it says run at least 87.

As far as any dyno's I've seen, higher octane fuels increase power?
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Old 01-03-2007, 11:20 PM   #16
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Quote:
Originally Posted by eTiMaGo View Post
Interesting read... I wonder if the engines here are tuned differently, as 91 octane is the lowest you can get, as well as 95...
i belive it is just a differance in how the octane is rated, i cant remeber any details on it..but i do belive that your lower octane is an equivilent to the north american lower octanes...
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Old 01-05-2007, 10:36 AM   #17
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I find it strange ~ That you guys are talking about 87.....89.....91.....93 octane fuel ~

Here in Australia we have 95.....98 and 100 octane fuel ~ I fill up with 98 octane fuel and there is quite a big difference with the regular fuel ~

That's my opinion anyway ~

Jaspie ~
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Old 01-05-2007, 03:48 PM   #18
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North America measures octane differently than the rest of the world so it's numbers do look lower. That said, I'm pretty sure american 87octane is slightly lower than the average regular in Europe. Probably why (or because) european cars have high compression rates, and american cars run a pathetic inefficient 8.5 or 9:1.
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