phil21191

When using Flex Fuel blending with Fuel Table Switch OFF in the Table Switching/Duel Fuel menu does Blend Curve (8) act as a global fuel multiplier?

Looking back through the way I had it setup I can simplify the way I currently have things configured and not use two VE tables

SpartanSV

IMO you want to use 2 tables as you should have different targets depending on the fuel you're using.

cpierr03

While not ideal, yes. You can adjust the percentages and it will change the multiplication table accordingly.

It's important to set your ethanol baseline properly using this method too - else you can run lean on pump gas. I used an ethanol test kit to verify the fuel coming out of the rail matched what my flex fuel sensor was reading.

phil21191

E85 price and availability in the UK is poor, I'm using Methanol it with Methanol. There is zero difference in power or the amount of ignition between 0.70 and 0.85 lambda so I target the same on pump fuel as methanol



Pump fuel in the UK is a maximum of 5% ethanol content and the Shell V-Power from the only station I use is consistently 3-4%

SpartanSV

That's cool for you bro but I'm not going to target .85 lambda at 20+ psi on 91 octane. However I would do that on e85. Same story with ignition. You want two different tables on a boosted miata.


/Thread

Savington

iTrader: (31)

More to the point, you need different fuel multipliers for low load cruise vs high load power settings.

This is a bad thread for bad ideas.

thebigtuna

Could you clarify what you mean? I was under the assumption you still target the same afr but the required fuel will just be more. Am I wrong in this understanding?

SpartanSV

In a knock limited application like a turbo miata you'll want to run a richer mixture for no other reason than to prevent detonation. Most people will target something like 11.0 AFR in boost on pump gas. If you change to a higher octane fuel then you don't have to run as rich of a mixture.


The same thing applies for ignition timing. On pump gas you'll run less timing to avoid knock. On e85, race gas, etc you'll no longer be limited by knock. You can run whatever timing gives the most power.

That's why you want 2 different fuel tables and 2 different ignition tables with blending.

thebigtuna

Thank you for that explanation! I've been targeting 11.8 at 14 lbs of boost on 91. I realistically hit 11.4 and call it good. Im sure I could pick up more power but I'd rather pick up power with boost than timing. I wish I had e85 as readily available as I used to.

Sorry for the derail

phil21191

The answer is carry on the way i have been by blending two VE tables then (As well as boost and ignition)

Savington

iTrader: (31)

Bingo. The "right" way is to start with a global multiplier and then trim using VE3, etc.