Turbo Selection

[My5ABaby]

Originally Posted by TitaniumTT

Not so much..... if you tune your car with a tank of e85 that is actually 85% ethanol, then go out and beat on your car and tank up with 70% ethanol..... where's your margin or error there? The OEM's know about this, which is why they have a sensor that will alter the fuel and timing maps based on the amount of ethaonal content.

I've been thinking about this... If I tune for E85 and actually get E70 in the tank, won't it just run a little rich? Also, most of today's pump gas varies in ethanol content. Presumably not 15% like E70 to E85, but it's still a variation.

Also, apparently the flex fuel sensor modulates the frequency and pulse width of the output to represent the ethanol content so I would need the Zeitronix (or some other) interpreter to change it to 0-5v output.

[FerociousP]

Originally Posted by My5ABaby

I've been thinking about this... If I tune for E85 and actually get E70 in the tank, won't it just run a little rich? Also, most of today's pump gas varies in ethanol content. Presumably not 15% like E70 to E85, but it's still a variation.

Also, apparently the flex fuel sensor modulates the frequency and pulse width of the output to represent the ethanol content so I would need the Zeitronix (or some other) interpreter to change it to 0-5v output.

I'm not so sure about the fuel sensor... You MAY be able to use the trim module input, with I think looks for a different voltage to determine its position, but you'd need way more that 10% to adjust for E85

[My5ABaby]

Originally Posted by FerociousP

I'm not so sure about the fuel sensor... You MAY be able to use the trim module input, with I think looks for a different voltage to determine its position, but you'd need way more that 10% to adjust for E85

The trim on the e6k looks for 2.5v. Anything over increases whatever setting up and below goes down. I would only use it for adjusting for e85 vs e70 or what not. Going from e85 to pump would definitely require a different map.

[Libor]

Originally Posted by My5ABaby

I've been thinking about this... If I tune for E85 and actually get E70 in the tank, won't it just run a little rich? Also, most of today's pump gas varies in ethanol content. Presumably not 15% like E70 to E85, but it's still a variation.

I came to same conclusion. Engine tuned for E85 would run about 9% richer with E70.

Also, I have very recent study which examines effective octane number of ethanol and several blends with gasoline. What is awesome about this study is the fact, that it separates effects of evaporative cooling from true, so called effective octane, which is based purely on chemical antiknock properties of given fuel.

Simply said, ethanol-gasoline blends, even with very low octane gasoline as base, have peak chemical knock resistance at about 50% volumetric ethanol content and any more ethanol content just increases cooling effect.

This brings another phenomena, for given air temperature, lower ethanol content fuel realizes more of theoretical charge cooling effect and vica versa.

So effectively, as far as knock resistance goes, E85 is no better than E70 or E50, unless the intake temperatures are over 100°C.