Homemade Premium?
Thread Starter
Joined: Apr 2005
Posts: 518
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From: South Dakota
Homemade Premium? In my area the highest octane gas you can buy is 91. I have a high compression heads/cam car and need higher octane fuel (92, 93). A couple of local guys were saying they make their own premium gas by mixing e85 with regular 87 octane gas to make around 93 octane gas. They say it works in their cars really well, they didn't need to modify anything, and its cheaper. I was wondering if anyone has done this before with a LS1 and what they are saying is true? Also, if it is feasible what ratio of e85 to regular would I have to mix for it to work?
You can figure up the e85 at around 100octane (from what I hear).
[(X gallons of e85) * 100 + (Y gallons of 91) * 91] / (X + Y) = Overall Octane...
But............
You get less heating value from e85, meaning you need to run it richer. e85 needs to be run at 9.76:1 AFR. You'll have to figure up a new air/fuel ratio to run each time, or use the same mixture each time.
[(X gallons of e85) * 9.76 + (Y gallons of gasoline) * 14.7] / (X + Y) = Ratio for e85 + gasoline.
[(X gallons of e85) * 100 + (Y gallons of 91) * 91] / (X + Y) = Overall Octane...
But............
You get less heating value from e85, meaning you need to run it richer. e85 needs to be run at 9.76:1 AFR. You'll have to figure up a new air/fuel ratio to run each time, or use the same mixture each time.
[(X gallons of e85) * 9.76 + (Y gallons of gasoline) * 14.7] / (X + Y) = Ratio for e85 + gasoline.
I would think, if you have the MAF enabled and fuel trims working off the your narrow band o2's that you could mix 25-30 E-85 with out issue. Iv'e heard the E-85 is 105 octane.
