What Octane?

[crager34]

Maybe I need a couple tanks to do this, but ran the HIGH stuff for a tank and got around 260 miles. Than ran the low stuff and got 250 miles. First thing I am hoping that I am getting the standard miles out of my VX - The second is... the price isn't worth ten miles and I didn't notice any performance issues.

[VXRaNgEr]

260 miles / 22.5 gallons = 11.6 mpg

Ouch. That's assuming you run to tank to bone dry though.

[Dallas4u]

RIGHT... meaning that, by the time you fillup (before bone dry), you actually receive less mpg.

By the way, I usually get between 260 - 280 miles per tank.

[ctp]

My average for the 1500 mile drive fom Texas was 19.979mpg. I started with a full tank, finished with a full tank and divided the miles by the gallons I got on the way. It seemed a little easier than running the tank dry

[Reg Hinnant]

here's something to try........
Read this http://www.rxp.com/Octane.htm
then this http://www.rxp.com/FAQs.htm
Dyno results http://www.rxp.com/test-cov.htm http://www.rxp.com/6.htm

Snake oil? Try a bottle and you tell me.

[Dallas4u]

Hmmm... why not. I may just pick some up after work tonight and try it. Hell, I did throw a toulene mixture in my tank a while back... can't be as nervous with this stuff as I was doing that!

[xdfarrx]

I read that due to atmospheric conditions above 4000 ft. octane above 87 is a waste as the conditions don't support the combustion to have any benefit. I read this a year ago in Petersen's offoad mag. At sea level the benefits are tangible apparently. I do as I read and here at sea level I rock as high octane as I can. An earlier thread suggested when the timing does have to be advanced by the ecu the car can get better fuel econ, which I was also told by a friend who worked in CART-

[xdfarrx]

Ooops I meant to say above 87 is a waste-

[WyrreJ]

That may be true, I haven't tried to think the physics through to check. But, it probably isn't true for cars with turbos or superchargers since they work by increasing pressure beyond the ambient air pressure, so sea-level or 9,ooo ft up, the pressure in the engine with a supercharger ought to be about the same.

[Chopper]

super chargers were made popular on WW2 aircraft to allow engines to operate at greater altitudes by compressing the thinner air to supply the o2 to allow operation at those altitudes. A supercharger at sealevel is vastly different than a supercharger at 9000 or 10000 ft. . Same for turbo... only diff is, belt or gas driven.

[Jolly Roger VX'er]

I run 87 octane and Mobil 1 SuperSyn Oil. First time in my life that low octane seems to perform well. All of my other previous rides either specified higher octane (Turbo) or simply "pinged" when it wasn't used. As for miles per tank...I haven't been able to break 300 miles on a tankful yet! usually around 260.

[Triathlete]

87 since I've owned it! Especially now that gas just went up 30 cents a gallon in the last 4 days here....OUCH!

[crager34]

Since my first post, I thought I would run a few tanks on various grades. Seem to be getting a little better mileage with the mid grade...I think it's 89 here in Columbus, OH. Better by about 10-20 miles is all.

[VehiP&J]

My wife and I just got our vx only used mid 89 octane in it. Actually nice we are used to only being able to use high octane 93 gas.

[WyrreJ]

Originally posted by crager34
Seem to be getting a little better mileage with the mid grade...I think it's 89 here in Columbus, OH. Better by about 10-20 miles is all.

FWIW, it is usually cheaper to buy 87 and 93 in proportion and let your gas tank mix them up to 89. In fact, that is usually what the gas station does at the pump anyway, they don't have a tank for 89.