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Unread 05-18-2007, 12:43 PM   #1
IWantMyMTZ
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Does Higher octane Help?

I remember when I took a shop class some years ago the shop teacher was telling us that your engine is calibrated, and designed to run on the octane gas that your maual says to use. He said those that decide to "treat" their engine to a higher octane gas every once and a while are just wasting money and screwing their engines settings all up.

I see exactly what he means but just out of curiosity does anyone run higher octane and get better gas milage?? any difference? just wondering...

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Unread 05-18-2007, 12:46 PM   #2
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Your shop teacher was 100% correct. There are zero benefits in running a higher octane that what your engine is rated for.
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Unread 05-18-2007, 12:46 PM   #3
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Unread 05-18-2007, 12:50 PM   #4
IWantMyMTZ
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just what i thought.....i was reading a thread a second ago about gasoline having enough detergent in it to clean out injectors to where you really dont need injector cleaner anymore. i got to thinking that maybe higher octane gas was better quality, cleaner, ect....

thanks for the input...
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Unread 05-18-2007, 12:52 PM   #5
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This is correct as far as engine performance goes. However, some brands of gasoline DO add specific detergent agents solely to their Premium gasolines. So, although the additional octane is not doing anything for the engine, the additional detergents are supposed to clean better than the cheaper (lower octane) gas they are left out of. If that's all marketing BS, I don't know.
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Unread 05-18-2007, 12:57 PM   #6
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In some engines with carbon buildup, like mine, a higher octane rating will quiet some of the pinging at lower rpms. It isn't helping anything, just masking a problem. People notice this and think that they NEED the higher octane, when in fact they need to clean the carbon out of their engine. I'm just too lazy lately.....
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Unread 05-18-2007, 12:59 PM   #7
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I heard running higher octane is bad for the jeep's engine, not just a waste of money. I forget where i saw this..any truth to it?
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Unread 05-18-2007, 01:02 PM   #8
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Quote:
Originally Posted by Mikey TJ
This is correct as far as engine performance goes. However, some brands of gasoline DO add specific detergent agents solely to their Premium gasolines. So, although the additional octane is not doing anything for the engine, the additional detergents are supposed to clean better than the cheaper (lower octane) gas they are left out of. If that's all marketing BS, I don't know.
Most major brands such as Chevron (the best) use their detergents (Cheverons is Techron) in all grades of gasoline. Its the discount or cheap gasoline that you need to be weary of. Your gasoline should idealy meet 'Top Tier' requirements.
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Unread 05-18-2007, 01:03 PM   #9
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I agree there is no reason for running a higher octane than you need to. One exception with mine was going up long hills it pinged like crazy running 87 octane. Switched to 89 octane and the pinging went away. 4.0, Auto, 3.73 gears, and 33" tires.
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Unread 05-18-2007, 01:18 PM   #10
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Higher octane is needed in engines with higher compression ratios to prevent pre-detonation or "knocking". An anti-knock agent is added to gasoline to increase octane. The agent does not improve MPG on engines not needing the additive.

If your engine knocks or is not running smoothly on the octane your owner's manual specifies, you may have the wrong heat range plug, i.e., too hot. Another reason, buildup on the valves, may cause pre-detonation. Since cleaning agents have been added to gasoline and tetra-ethyl lead is no longer used as an anti-knock agent, plug fouling and valve contamination are not as prevalent as it used to be.
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Unread 05-18-2007, 01:22 PM   #11
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Quote:
Originally Posted by tjones07
I heard running higher octane is bad for the jeep's engine, not just a waste of money. I forget where i saw this..any truth to it?
I heard the same thing, higher octane cleaner gas burns hotter doing more damage to your engine. Don't know how much truth there is to it.
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Unread 05-18-2007, 01:48 PM   #12
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Quote:
Originally Posted by edzakory
Higher octane is needed in engines with higher compression ratios to prevent pre-detonation or "knocking". An anti-knock agent is added to gasoline to increase octane. The agent does not improve MPG on engines not needing the additive.

If your engine knocks or is not running smoothly on the octane your owner's manual specifies, you may have the wrong heat range plug, i.e., too hot. Another reason, buildup on the valves, may cause pre-detonation. Since cleaning agents have been added to gasoline and tetra-ethyl lead is no longer used as an anti-knock agent, plug fouling and valve contamination are not as prevalent as it used to be.
I believe this is basicaly right
Gasoline contains a mix of hydrocarbons, and the amt of good burning octane C8H18 is where the octane rating comes from. It is necessary on engines with higher compression ratios. If your engine was designed with 87 in mind use it. 89 in an 87 engine can possibly do some good, but it will be so small (because your engine isn't meant for that) you will not notice a difference, and you're throwing your $ at big oil. If you engine is kocking on 87; 89 is a tempoarary fix, not a permanant solution. I'm not sure exactly how modern electronics factor into this basic idea.
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Unread 05-18-2007, 02:17 PM   #13
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Sorry but have to jump in say HELLLLLLLLLLLLL NO

if you drive a Z06, Viper, Supercharge Stang then yes




What gets me fired up is , these damn dealers tellyou put in the high octane in a normal engine WTF 5.3L Chevy motor dont need HI OCTANE

I worked with this one lady I got in a pissing match with cause she thought her 1.8L yota need the HI OCTANE , told her full of ship you money at $3.30 a gallon

sorry that just arrrrrrrrrrrrsssss me
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Unread 05-18-2007, 02:36 PM   #14
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Quote:
Originally Posted by sknight
I heard the same thing, higher octane cleaner gas burns hotter doing more damage to your engine. Don't know how much truth there is to it.
There's no truth whatsoever to that rumor. There is no additional "energy" in gasoline containing more octane than there is in a lower octane fuel so there's nothing to make it burn hotter.

Understand that octane is an additive and it's SOLE purpose is to increase the level to which it must be compressed before it detonates (from compression). So a high compression engine needs a gasoline with more octane so the engine's compression won't be enough to detonate the gasoline prematurely, i.e. before the spark plug is supposed to ignite the air-fuel mixture. Spark knock/detonation is just the fuel prematurely self-igniting from compression.

So if your engine runs without pinging with 87 octane, treating it to an occasional tank of 89 or 91 octane does nothing except make that sale more profitable to the dealer and manufacturer.

What can make an engine ping when it's running the recommended octane gasoline? Usually nothing more than a build-up of carbon inside the combustion chambers usually caused by not driving the engine aggressively enough. The built-up carbon continues to glow slightly after the last combustion stroke so during the next compression or combustion stroke, the glowing carbon can ignite the gasoline prematurely causing ping or knock.

And as said above, major brands of gasolines all contain basically the same amount of fuel injector cleaners and other additves. The amount of octane contained being the only real difference between their various octane levels of gasolines.
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Unread 05-18-2007, 02:37 PM   #15
tj99
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Quote:
Originally Posted by edzakory
Higher octane is needed in engines with higher compression ratios to prevent pre-detonation or "knocking". An anti-knock agent is added to gasoline to increase octane. The agent does not improve MPG on engines not needing the additive.
True, higher octane gas also burns slower than lower octane. That's why it reduces the knock tendency. If your vehicle isn't designed for the octane with higher compression it will take more fuel to make the same heat / power.

Years ago I had an old 73 Plymouth 318 that I put a half a tank of Turbo Blue racing gas in. It was so expensive, about $2 a gallon that I could only afford a half a tank. Filled it up with premium the rest of the way. It got the worst mileage after that ever.

I just found this article, it explains it pretty good.
http://www.bajajusa.com/High%20Octane.htm
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