Contour Enthusiasts Group Archives Forums General Troubleshooting FUEL seclection

Hey,

Ok, i get 500km a tank on regular fuel and only 300km a tank on premium.

I figured by using a higher octane i might gain a few kms per tank. Can someone explain to me why i am terribly wrong?

thanks,jca

I was always told that all gasoline has the same BTU energy potential. The additives that increase the octane to 89 or 92 prevent knocking that occurs with higher compression engines. That using 92 octane in a car rated for 87 was just a waste of money.

Premium has a higher flash point. (slower to ignite)

Normally aspirated vehicles.

The cars requiring premium normally have advanced ignition timing starting the flame front earlier and allowing for a longer burn time.

A car programmed to run regular fuel would still have timing set for regular fuel and not start the flame front as early and therefore lose power and efficiency because the fuel was not achieving maximum burn time.

Simple explanation. Other factors are involved as well.

I agree with DemonSVT.

Same thing happened to my Tour, until I installed a DiabloSport chip.
The chip requires 91 octane or higher for the best performance.
With the chip installed, I am using 93 octane now, and getting the same MPG as 89 octane.

Even BETTER highway MPG.

I get 520km on a tank of gas driving hwy/city with a heavy foot! Plus I use 92 octane all the time!

I don't know why you would have such a big difference and I don't!

Make sure that your driving habits and city/hwy are the same when you do the comparison.

Stephen

I respect your opinion (the flash point thing I'm not sure about right now, still checking), but I have to disargee with you on that one. I get better mileage out of the 92/93 octane than I do the 87 in both of my vehicles, and I have no altered computer program/chip in either. For some reason in my tours early life (under 10K), the premium gas I used actually killed 4 O2 sensors. I switched back to 87, no more lost O2 sensors. Now the real funny part is that I went back to 93 octane again and I haven't lost an O2 sensor since November 2000. I have no clue what to make of my car sometimes...