12P Flex Fuel Discussion

[MAGP]

I'm very interested in flex fuel and would love to see it on the venerable Delcos. Just as an aside it take a little bit of time but eventually tuning by Lambda becomes 2nd nature when you tune with multiple fuels. On the Lambda scale they all have max power etc at about the same lambda value whereas in AFR, as already posted a few pages ago by another member, they vary alot.

[Holden202T]

yeah i normally change the wideband in my car to lambda when im on the dyno as thats what the dyno operator likes to see, but it still inputs methanol AFR's into the data stream to compare against my target afr....

for those wanting to do it you can pretty easily change the calcs in the adx to show lambda numbers ..... just divid the reading by 14.7 (for petrol) and it will show you lambda.

[vlad01]

I'm already used to E85 arf and easily know what the equivalent is in petrol.

You learn fast when you have to convert so many tables when setting up for E85

[Holden202T]

yeah experience and practice is the key to knowing whats what with different fuels.

[MAGP]

Certainly is, however a tuner working with 1 set of numbers instead of 3 or more is going to have it alot easier.

[vlad01]

Maybe but I did come across a thread where a guy blew his engine up as he tuned it to the petrol arf while his wide band meter was set on ethanol

so 11.5:1 on e85 is so stupidly lean for 25 psi boost I recall reading lol

So really that also can be a source of confusion too.

[MAGP]

Maybe but I did come across a thread where a guy blew his engine up as he tuned it to the petrol arf while his wide band meter was set on ethanol

so 11.5:1 on e85 is so stupidly lean for 25 psi boost I recall reading lol

So really that also can be a source of confusion too.

That really doesn;t have anything to do with setting mixture by lambda, if he did it all by lambda he wouldn't have to worry about petrol afr and ethanol afr, all he would need to remember is lambda 1 for stoichiometric and whatever value he needed for 25psi. It sounds more like the entire setup wasn't checked before he started tuning.

[vlad01]

Maybe but I did come across a thread where a guy blew his engine up as he tuned it to the petrol arf while his wide band meter was set on ethanol

so 11.5:1 on e85 is so stupidly lean for 25 psi boost I recall reading lol

So really that also can be a source of confusion too.

That really doesn;t have anything to do with setting mixture by lambda, if he did it all by lambda he wouldn't have to worry about petrol afr and ethanol afr, all he would need to remember is lambda 1 for stoichiometric and whatever value he needed for 25psi. It sounds more like the entire setup wasn't checked before he started tuning.

yes but the point is there is many ways to reference off, no one method is correct and this can lead to mistakes for inexperienced or misinformed tuners.

Everyone I personally know of tunes by afr as that is our preference. Like wise I would have to convert everything I know to lambda as I have no clue outside lambda 1 what that means.

I personally use the afr that correspond to the fuel being used as thats what 12P tables are for. eg when I see 7.4:1 on e85 I know thats about 12.7 equivalent in petrol and 9.8 approx 14.7

And thats literally all you have to do in 12p or similar, change the target tables to the e85 afrs and it automatically gives you the correct fueling.

[TdracerTd]

Maybe but I did come across a thread where a guy blew his engine up as he tuned it to the petrol arf while his wide band meter was set on ethanol

so 11.5:1 on e85 is so stupidly lean for 25 psi boost I recall reading lol

So really that also can be a source of confusion too.

That really doesn;t have anything to do with setting mixture by lambda, if he did it all by lambda he wouldn't have to worry about petrol afr and ethanol afr, all he would need to remember is lambda 1 for stoichiometric and whatever value he needed for 25psi. It sounds more like the entire setup wasn't checked before he started tuning.

yes but the point is there is many ways to reference off, no one method is correct and this can lead to mistakes for inexperienced or misinformed tuners.

Everyone I personally know of tunes by afr as that is our preference. Like wise I would have to convert everything I know to lambda as I have no clue outside lambda 1 what that means.

I personally use the afr that correspond to the fuel being used as thats what 12P tables are for. eg when I see 7.4:1 on e85 I know thats about 12.7 equivalent in petrol and 9.8 approx 14.7

And thats literally all you have to do in 12p or similar, change the target tables to the e85 afrs and it automatically gives you the correct fueling.

On that though, The petrol AFR that you are aiming for is the same for E85, once you reference back to lambda. I fear I am not explaining what I am trying to say correctly, But the AFR is merely a scale. If your wideband is set to petrol AFR readouts or Lambda (and I would only tune off a wideband), then the reading will be the same for 9.76:1 e85 and 14.7:1 Petrol, ie it would read 14.7. At RBT it would read 11.76, but your actual AFR on e85 would be 7.8. So the correction you make will be correct regardless of what's in your AFR table as it is just a percentage. Not saying you are wrong, just saying that there is logic to the way I do it also, and it works, (again, not saying anyone else's method doesn't work). I find it confusing to swap between different scales, I have Lambda on my wideband readout, and in tunerpro I have petrol AFRs in my table and I log in petrol AFR's (that's only because for the calculations, right or wrong I figured the scale may lack resolution), then all I need to know is what I'm aiming for in petrol and what that is in lambda. Fuel is irrelevant.

[MAGP]

On that though, The petrol AFR that you are aiming for is the same for E85, once you reference back to lambda. I fear I am not explaining what I am trying to say correctly, But the AFR is merely a scale. If your wideband is set to petrol AFR readouts or Lambda (and I would only tune off a wideband), then the reading will be the same for 9.76:1 e85 and 14.7:1 Petrol, ie it would read 14.7. At RBT it would read 11.76, but your actual AFR on e85 would be 7.8. So the correction you make will be correct regardless of what's in your AFR table as it is just a percentage. Not saying you are wrong, just saying that there is logic to the way I do it also, and it works, (again, not saying anyone else's method doesn't work). I find it confusing to swap between different scales, I have Lambda on my wideband readout, and in tunerpro I have petrol AFRs in my table and I log in petrol AFR's (that's only because for the calculations, right or wrong I figured the scale may lack resolution), then all I need to know is what I'm aiming for in petrol and what that is in lambda. Fuel is irrelevant.

Very true