I just got my Diablo chip on Friday(Thanks Ken for the expeditious service). I had a flowmaster installed Wednesday so I filled my tank with 87 octane Thursday night because I wanted to see the impact on gas mileage. Now the question is how to get the octane rating up to the required grade. I figured I'd run this tank down to just a couple of gallons and then fill up with premium.

The real question: Is there a formula to calculate octane ratings when mixing different grade fuels? I don't intend to mix fuel in the future but I do need to address the first tank. Of course I could just wait a couple weeks and run through a couple of tanks of premium but I have a new toy and don't know if I can wait that long.

I'm posting in this forum because the question is directly related to using a chip and this info may be useful to others when installing a chip.

Thanks
Tim

 

My experience is that if you have a quarter tank of 87, and mix it with 3/4 tank of 93 octane, it doesn't give you enough octane to meet the 91 requirement (ie, still pings on inclines). Of course this may have to do with the non-linear scale of the Ford fuel gauge.

If you get it down a couple of gallons and fill with premium, its not a problem. Just throw in some octane booster.... use the cheap $2.00 stuff as been my experience that it works as well as the expensive stuff (ie., only raises octane by about a point at most).

 

Thanks. I'll do that. The low fuel light should come on today or tomorrow. When it does I'll drive it another 20 miles or so then fill up and add some octane boost. Oh man I can't wait. Getting new stuff for my truck is always too much fun.

Tim