Can I mix E85 with Premium?

[GTSnake]

If I mix E85 with 93/94 octane would I increase the octane in my tank? At what ratio would the alchohol damage my non-alchohol rated fuel system?

I figure if I mix E85 50/50 I should get it up to 96-97 octane right?

[Tom, F&L GoR]

Non-E85 fuel systems can tolerate 20% ethanol, not limited by compatibility, but because of the range of air-fuel ratio adjustments the ECM can make. E85 (85% ethanol) has only ~70% of the energy that "E0" (100% gasoline) would have so the engine would run lean.

http://www.e85fuel.com/forsuppliers/...gy_content.doc

Note: this is an E85 advocate site

[GR8_ASP]

Tom (GTSnake),

Note that your engine cal is not stock. Adding ethanol in any amount will raise your air-fuel ratio. That may be more limiting than the resulting octane. Note also your system does not adjust for reduced density, it is volume based only (really injector pulse width). If you have injector duty cycle room, you could create a cal for increased volume flow under WOT conditions and let the PCM adaptives cover the part throttle realm. As Tom indicates the limit for that is probably around 10-20%. You can check your current adaptives to determine how much is available.

[GTSnake]

So in other words I should only mix up to 20% alchohol max and richen my AF ratio?

[ROGUE]

So in other words I should only mix up to 20% alchohol max and richen my AF ratio?

Honestly if you're going to go through the trouble just set it up to run 100%. Ethanol is not nearly as corrosive as Methanol so it won't hurt a thing in the fuel system.

Also being an alch based fuel you need to run it very rich to achieve the proper stoch ratio. With E85 it's in the very low 10 range.

If you're running a boosted or nitrous car you can see HUGE power gains from running E85 (with the proper tuning) but on a fairly stock N/A car it's going to be about the same as regular pump gas.

[GR8_ASP]

So in other words I should only mix up to 20% alchohol max and richen my AF ratio?

Higher air-fuel is leaner, not richer. Alcohol wants a higher flow rate due to its lower density and oxygenation.

[GTSnake]

[quoteHigher air-fuel is leaner, not richer. Alcohol wants a higher flow rate due to its lower density and oxygenation. "Adding ethanol in any amount will raise your air-fuel ratio. "


[/quote]

But isn't that the same thing? If it runs leaner shouldn't I richen it up to compensate? Or is it supposed to run leaner?