AFR for PE on E10
Thread Starter
Drifting
Joined: Aug 2009
Posts: 1,971
Likes: 243
AFR for PE on E10
I’ve had a lot of threads for tuning lately, sorry for that, but they seem to get more attention when it’s a specific title vs a general tuning thread.
The only gas available here is e10. Tuning non-PE shouldn’t be a prob. Narrowband o2 sensors are none the wiser and as long as I tune with e10 then it’s running at the stoich ratio for e10 (something like 14.1:1).
BUT… what about power enrichment, where I am using a wideband sensor pinned to my pcm and it is reporting an AFR. I’ve been aiming for 12.7, but I think that might be a straight gasoline number. What would be the right AFR for PE on e10? I’ve read as low as 12:1, but can’t say I know that would be right.
I commonly see 12.5-12.9 :1 referenced as a good target AFR for PE (for gas). 12.5:1 represents a 15% richening of a stoich 14.7:1 ratio. That same 15% logic applied to an e10 14.1:1 yields 12:1 PE AFR.
Thoughts on this? Not sure there is much consideration around this for e10 but maybe some e85 guys can share wisdom around this.
The only gas available here is e10. Tuning non-PE shouldn’t be a prob. Narrowband o2 sensors are none the wiser and as long as I tune with e10 then it’s running at the stoich ratio for e10 (something like 14.1:1).
BUT… what about power enrichment, where I am using a wideband sensor pinned to my pcm and it is reporting an AFR. I’ve been aiming for 12.7, but I think that might be a straight gasoline number. What would be the right AFR for PE on e10? I’ve read as low as 12:1, but can’t say I know that would be right.
I commonly see 12.5-12.9 :1 referenced as a good target AFR for PE (for gas). 12.5:1 represents a 15% richening of a stoich 14.7:1 ratio. That same 15% logic applied to an e10 14.1:1 yields 12:1 PE AFR.
Thoughts on this? Not sure there is much consideration around this for e10 but maybe some e85 guys can share wisdom around this.
Safety Car
Joined: Sep 2001
Posts: 4,155
Likes: 553
From: Glenbeulah Wi
Still target 12.7 the wideband works on lamda and then shows a gas afr. It has no idea what fuel you are using and 12.7 will still be the correct afr since the sensor is reading lamda. If you calibrate the sensor to display e10 ratios the displayed 12.7 would be 12.1.
Melting Slicks
Joined: Mar 2002
Posts: 2,874
Likes: 764
From: Sligo PA
This is why I wish so badly that Holley ( or most tuning software for that matter) would allow you to tune in lambda instead of afr. A 1 lambda is stoic no matter what fuel is used. I use a flex sensor and go back and forth between E10 and E85 all the time. So the afr thing is always a hurdle for me in tuning because afr is the only option the software will give me.
Drifting
Joined: Jun 2020
Posts: 1,695
Likes: 728
From: Stay dangerous my friends
This is why I wish so badly that Holley ( or most tuning software for that matter) would allow you to tune in lambda instead of afr. A 1 lambda is stoic no matter what fuel is used. I use a flex sensor and go back and forth between E10 and E85 all the time. So the afr thing is always a hurdle for me in tuning because afr is the only option the software will give me.
Melting Slicks
Joined: Mar 2002
Posts: 2,874
Likes: 764
From: Sligo PA
It does. And if you need Lambda based AFR numbers you check the gasoline box, even with other fuels and it was designed this way for the Holley system. Offsets are provided to estimate true AFR but that typically confuses things. As mentioned, the wideband sensors measure Lambda regardless if the fuel and show the 14.7 at 1 Lambda, so its not showing AFR.
