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I've got a little gas


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I have a little gas question. Since we all drive the same cars I'd like to know what type of gas do you use and why? I'd like to know what burns best. Shell, Texaco ect. 87 octane, mid grade or super 92 or 93? Which gas should we be trying? Let's take a poll. I haven't been using any one company for my petro. How do you feel about your gas? wink.gif

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87 Oct. any station, aroung 30 mpg hwy.& 20-22 city.

Yeah, have had many 4 cyls. not do this good.

Tried 93 Oct. a few times but couldn't tell a diff.

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I would use the grade called for unless the engine obviously knocks. I use 30 to 32 PSI in my tires because that is what is called for. Anyone using 40 to 42 PSI how about 50 to 52 PSI is more always better confused.gif <span style="font-style: italic">Don't even think of it though. For illustration purposes only.</span>

90% of the time I use Sunoco 87 in the Reatta!

Now a question for all...I have found on several occasions that I can go an extra 15 to 20% farther using Amoco gas. I have found this on long multi-day trips where I use a calculator and math to calculate mpg. It is not available locally frown.gif

It doesn't make a great deal of sense to me but have observed it several times confused.gif

PS; I also use a shot of Redline Complete Fuel System Cleaner at the recommended concentration of 1 bottle to 100 gallons. This is something the BMW guys recommend to keep the combustion chamber just that much cleaner!

good reading if you want to take the time I buy it by the case. Best case price I have found.

jchudyk8383 I don't know about this for certain but it is my belief that water in the gas tank with regular gas just stays there BUT with ethanol it gets "absorbed?" into the gas and gets burnt right along with the gas. Water is removed from the system with ethanol by my understanding and therefore reduces rust/corrosion in the fuel system? Could be wrong but this is my understanding. Others . . .

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Run the minimum octane required to keep knock under control. The factory chip is calibrated for 87 octane. If you check your diagnostics occassionaly you can see if you are experiencing any spark retard due to knock. If not, more octane won't help. I do believe in running one brand of fuel if at all possible and from the same station if feasible. Any fuel related problems will be a lot easier to track back if they occur. I do run Amoco 93 octane exclusively but I need it for the aftermarket PROM, and 87 works perfectly with the stock chip. I am not necessarily recommending this brand, although it has never given me any problems, so try different brands until you find one that starts and runs well and stick with it.

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Good comments. Just some added notes:

A Northwestern University professor wrote a textbook back in the 50's that was the bible for engine design-as I remember it was called "Internal Combustion Engines". It said the Btu rating was higher when the octane rating was less. So 93 octane would give less mileage than 87 octane. This was true, unless the 87 octane did knock, which then gave less power--and therefore less mileage per gallon.

Also on ethanol, before Reattas (2) I used only ethanol in my 87 Honda Accord and got up to 39 mpg on straight road run (with 5 speed0. And as for as ethanol hurting the engine, I never did anything but tune the engine and use Mobil 1 oil. After 225,000 miles, the engine purred as I drove it to the charity for a donation.

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I'd be careful with tire pressures. Every tire has a maximum usable pressure, and a specific load it can carry at that pressure.

I don't know what the load/pressure numbers are for any specific tire. Unless you do, I wouldn't chance it.

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a) my street cars all are tuned for 87 PON. Least cents per mile.

B) Higher compression results in more power per stroke but also necessitates higher octane (slower ignition/burning) and as a result, more ignition advance. Are minor differences in BTU/whatever but I have always ignored that as insignificant.

c) have found a correlation between octane requirement and cylinder bore for the same c/r - a 4.25" bore engine will require a higher octane than a 3.75" bore. Similarly a head with the plug in the middle of the chanber (or a little closer to the exhaust valve) and a spherical chanber will need less octane than a wedge with the plug in the side. Has to do with the flame front propagation.

d) not at home but have two books by that name, one by Lester C. Lichty and the other by Edward F. Obert. My root source though is Sir Harry Ricardo's "The High Speed Internal Combustion Engine".

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