# Flex Fuel Blends Calculations

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I'm looking to run E30-E40. I don't have enough injector or pump to go full E85, so I won't be tuning the second fuel at full strength for the tables to extrapolate between in the blend table.

The Link help files give all of the fuel density, stoich ratios, etc for E85.

So lets say E30 is going to be my second fuel would I tune the car on E30 and set up the Multi Fuel Blend Ratio Table so that everything over E30 is at 100% and leave the known ethanol properties in the multi fuel table.

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The suggested option would be to calculate the correct density and stoich ratio settings for E30, then as you say your blend ratio table can use 100% of fuel #2 settings when the flex sensor is reading 30% eth.

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Bugger. I was hoping that would not be the case. I couldn't work out how to do the calculations. My BP 98 petrol here is 14.4 stoich.

I have been trying to google the information to no avail.

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30% eth @9:1 with 70% petrol @ 14.4:1 would give you a stoichiometric ratio of about 12.78:1.

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Thanks Adam. I'm working away so can't respond to this as often as I'd like. Does the Density Temp Coefiicient make a big difference?

Can you show me the equation to do the calculations

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Another one? What would the injector flow rate be at 43.5 psi for ID 1050x.

There is g4 characterization data on the ID website but no specific to ethanol

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• 5 months later...
On 9/30/2019 at 2:42 AM, Adamw said:

30% eth @9:1 with 70% petrol @ 14.4:1 would give you a stoichiometric ratio of about 12.78:1.

Hey adam, i’m in a similar boat but i’m running  60% mix. How did you calculate this? i’m currently switching to modelled mode from traditional and i don’t know what to set as the stoich ratio/density for my fuel

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0.3*9+(0.7*14.4) is the calculation he made.

for you it would be 0.6*9+(14.4*0.4)=11.16

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