Printable View
Im tuning my daily to run on e85. Its just a bolt on truck. I already have my stoich set to 9.7. I want to achieve .85 Lambda/12.5 AFR at WOT. My question is, do I set the Power Enrichment vs RPM at 1.176 (gas 12.5 AFR) or set it for 1.771 (8.3 E85 AFR)?
First one
Interesting. I know you can tune e85 using gas afr numbers, but why would you change stoich to 9.7 (E85 afr)but keep the WOT at the gas afr? Its logicial to change both to the e85 afr numbers. Not saying your wrong, just want to learn.
That's just how they work.
Put 9.7/1.176 and you get nearly 8.3 on the E85 afr.
Thats weird. Thanks for the input!
Just talk lambda and it makes sense!
I get it now, I feel like a ding dong. Using the math to figure out power enrich with gas afr is the same as using e85 afr. Comes out really close. I was over thinking it! Thanks again guys.
That's why even though within the tune files for GM platforms the fueling is not shown in terms of Lambda with all of the ethanol blended fuels and whatnot these days it is so much easier to think and use Lambda.
Well most GM calibrations that is, some do use Lambda.
Is 85 lambda good to shoot for? I red this is on the lean end of max power for e85. Would 80 or 83 be better? Not much info on NA e85 set ups out there
Question: Where did the 1.176 come from?
I understand 1.0 lambda = e85 afr 9.760= gasoline afr 14.7
And if you take 1?e85 afr of 9.7 gives you a Fuel/Air ratio value of
=0.1030927835
And
1? gasoline afr of 14.7, gives you Fuel/Air ratio of
=0.0680272109.
Just curious what the 1.176 represents, I'm running e85 and cant get it to get richer than .84 lambda even after power enrichment. I used .1015 as my stoich value, runs great, but i want to spray it, and I need a target lambda around .78-.77 lambda
The 1.176 would be the value you would use if you wanted 12.5 AFR or .85 lambda using the gas scale.
So you take your stoich value of 14.68 for gas and divide by 1.176.
14.68/1.176 = 12.49 afr.
14.68/1.280 = 11.46, which is the same as .78 lambda. (.78 x 14.68 = 11.45)
Just remember that the commanded value is a set and forget table. You ask it to request .78 lambda but you never change that value again. You have to play with the actual airflow model to achieve what you are commanding. The MAF and or VE tables are where you add or remove fuel to reach your targets.