Ever fill up with premium?
09-01-2010, 09:09 AM
#16
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Premium better than regular?.........the myths just keep on keepin' on. At only 8.8:1 compression for the XJ 4.0, a lawn mower probably has more. I'm still looking for valid info (not opinions) that says premium is better for, improves mileage, makes the engine quieter, even though the owners manual says regular is fine. Someone help me out here.
http://www.consumerenergycenter.org/...s_premium.html
http://www.cartalk.com/content/featu...questions.html
http://www.straightdope.com/columns/...nd-regular-gas
http://www.usatoday.com/money/autos/...emiumgas_x.htm
http://www.epinions.com/content_2346164356
http://www.edmunds.com/advice/fuelec...3/article.html
http://www.caranddriver.sg/features/...emium_-feature
http://www.consumerenergycenter.org/...s_premium.html
http://www.cartalk.com/content/featu...questions.html
http://www.straightdope.com/columns/...nd-regular-gas
http://www.usatoday.com/money/autos/...emiumgas_x.htm
http://www.epinions.com/content_2346164356
http://www.edmunds.com/advice/fuelec...3/article.html
http://www.caranddriver.sg/features/...emium_-feature
All more octane does is resist predetonation from advanced timing, high compression, or boost.
If you're seeing higher mpg from premium on an 8.8:1 XJ, I agree with the notion that it's because regular gas these days tends to be 10% ethanol, while premium is 100% gasoline. Ethanol contains less stored energy than gasoline, and generally the higher the ethanol percentage, the lower the gas mileage.
09-01-2010, 09:14 AM
#17
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I tend to agree with this. Higher octane is necessary for higher compression, period. I run premium in my Civic because it's running 10.5:1 compression. I run regular in my XJ because it runs 8.8:1.
All more octane does is resist predetonation from advanced timing, high compression, or boost.
If you're seeing higher mpg from premium on an 8.8:1 XJ, I agree with the notion that it's because regular gas these days tends to be 10% ethanol, while premium is 100% gasoline. Ethanol contains less stored energy than gasoline, and generally the higher the ethanol percentage, the lower the gas mileage.
All more octane does is resist predetonation from advanced timing, high compression, or boost.
If you're seeing higher mpg from premium on an 8.8:1 XJ, I agree with the notion that it's because regular gas these days tends to be 10% ethanol, while premium is 100% gasoline. Ethanol contains less stored energy than gasoline, and generally the higher the ethanol percentage, the lower the gas mileage.
09-01-2010, 09:28 AM
#18
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09-01-2010, 09:30 AM
#19
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I usually use premium when my Jeep's are due for California smog tests, the reason being as the fuel burns hotter the emissions are less from the exhaust pipe. 
09-01-2010, 10:41 AM
#21
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Last edited by Vindicator9000; 09-01-2010 at 10:44 AM.
09-01-2010, 11:15 AM
#23
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Here in Iowa, the home of ethanol, we have 3 grades of fuel. Cheapest to highest they are Ethanol 89 octane, regular or super unleaded (no alcohol) 87 octane and premium...don't know the octane.
Even though ethanol has higher octane it is widely accepted that 100% gasoline will give better mileage.
Even though ethanol has higher octane it is widely accepted that 100% gasoline will give better mileage.
09-01-2010, 02:54 PM
#28
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Yes directly into TB But like was stated earlyer must be VERY careful, when injecting it this way allowes proper distrubtion throughout intake ports. tube diameter that of WD-40 red straw im using hobby hose from nitro rc truck.
Do your own reasearch for what is right for you good luck
09-01-2010, 03:52 PM
#29
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I buy premium here in cove OR. because it has no Ethanol. It cost me about 8% more than the regular with Ethanol but in my F150 I get between 17% and 23% better mileage. I use it in everything I own Motorcycle, Cherokee, 1948 CJ2A, and a supercharged Buick, but it is suppose to run 93 octane. I don't keep track of mileage for the Motorcycle because it only has a 5.9 gallon tank and I ride it hard, the Cherokee and the CJ2A I drive mostly in the mountains so I don't keep track of their mileage either.