AFR's and E85
08-04-08, 02:25 PM
#1
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AFR's and E85
What AFR is everyone tuning for on E85?
Also, what AFR is everyone running at idle?
Got my wideband hooked up this weekend, and it's running 10.5 at idle and my eyes are on fire.
Also, what AFR is everyone running at idle?
Got my wideband hooked up this weekend, and it's running 10.5 at idle and my eyes are on fire.
08-04-08, 03:18 PM
#2
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Ran my car for about 20 minutes yesterday, engine block was cool to touch and the intake and carb hat was ice cold. Cool stuff.
This was without the waterpump ON.
This was without the waterpump ON.
Last edited by Viking War Hammer; 08-04-08 at 03:28 PM.
05-05-11, 10:53 AM
#7
Know this is an old topic, but have to post.
I was running my AFR's in the high 11's and a friend told me that was too much fuel.
I leaned it out to around 12.2:1.
My car is a different car! It has way more power and torque.
My friend said you can lean E85 out to about 14:1 without any damage.
He also said running it rich is more harmful than running it lean.
I was running my AFR's in the high 11's and a friend told me that was too much fuel.
I leaned it out to around 12.2:1.
My car is a different car! It has way more power and torque.
My friend said you can lean E85 out to about 14:1 without any damage.
He also said running it rich is more harmful than running it lean.
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05-17-11, 02:55 PM
#11
Finally something I know a little bit about.... lol.
Here's the story with E85 guys. You can't think in terms of AFR anymore... it will just confuse the crap out of you. You need to tune in lambda. Any wideband on the market will display in lambda. There's a ton of info out there on the web regarding lambda so i won't get too deep into it. But lambda is essentially the stoichiometric value of a given fuel, or basically the ratio at which all the fuel is consumed during the combustion process.
So knowing that 1.00 lambda represents our theoretical balance point and a higher number is leaner and a lower number is richer we can determine where we should be in terms of fuel ratios by knowing the stoich values of the fuels in question. Here's a list of stoich values for some common fuels:
Gasoline: 14.64 (but closer to 14.08 now that most fuel is blended with ethanol)
C16: 14.77
GT Plus: 13.80
E85: 9.85
Given this info we can now convert the lambda to AFR and vise versa.
For example: Most boosted rotaries run well and safely between 11.2 and 11.8 AFR on gasoline. So converting to Lambda would look like this... 11.5/14.08 (or 14.64)= 0.785 lambda. If you're wideband is displaying in lambda this is the value you will see.
If this same engine is converted to run on E85 you would use the same lambda values as lambda remains constant. So.... 0.785x9.85 (stoich value of E85)= 7.73 AFR. So.... as you can see E85 is run considerably richer than gasoline. This is largely the reason why converting to E85 requires upgrading the fuel system in terms of both flow and overall capacity. A typical increase of 30-35% is expected when going to E85 from gasoline.
So the above posts claiming 11's and 12's would be crazy lean on E85.... FYI.
The other nice thing about tuning in lambda is that it's really easy math to make corrections. Another example.... if my desired lambda is 1.00, say for cruising, and my actual lambda being displayed is 1.10 on my wideband, then I am 10% lean on my tune and need to add 10% to my VE table/fuel map/etc. Conversely if I was seeing .90 i would know I was 10% rich from my target.
Here's the basic formula for making corrections when tuning in lambda: (actual Lambda)/(desiredl Lambda)= correction factor
so 1.10/1.00=1.1
or
0.65/0.785= 0.82 or an 18% correction
hope that kinda makes sense as I was typing this up in a hurry while at work... in case anyone was wondering I am an EFI calibrator and tune cars for a living, so feel free to ask any questions.
Here's the story with E85 guys. You can't think in terms of AFR anymore... it will just confuse the crap out of you. You need to tune in lambda. Any wideband on the market will display in lambda. There's a ton of info out there on the web regarding lambda so i won't get too deep into it. But lambda is essentially the stoichiometric value of a given fuel, or basically the ratio at which all the fuel is consumed during the combustion process.
So knowing that 1.00 lambda represents our theoretical balance point and a higher number is leaner and a lower number is richer we can determine where we should be in terms of fuel ratios by knowing the stoich values of the fuels in question. Here's a list of stoich values for some common fuels:
Gasoline: 14.64 (but closer to 14.08 now that most fuel is blended with ethanol)
C16: 14.77
GT Plus: 13.80
E85: 9.85
Given this info we can now convert the lambda to AFR and vise versa.
For example: Most boosted rotaries run well and safely between 11.2 and 11.8 AFR on gasoline. So converting to Lambda would look like this... 11.5/14.08 (or 14.64)= 0.785 lambda. If you're wideband is displaying in lambda this is the value you will see.
If this same engine is converted to run on E85 you would use the same lambda values as lambda remains constant. So.... 0.785x9.85 (stoich value of E85)= 7.73 AFR. So.... as you can see E85 is run considerably richer than gasoline. This is largely the reason why converting to E85 requires upgrading the fuel system in terms of both flow and overall capacity. A typical increase of 30-35% is expected when going to E85 from gasoline.
So the above posts claiming 11's and 12's would be crazy lean on E85.... FYI.
The other nice thing about tuning in lambda is that it's really easy math to make corrections. Another example.... if my desired lambda is 1.00, say for cruising, and my actual lambda being displayed is 1.10 on my wideband, then I am 10% lean on my tune and need to add 10% to my VE table/fuel map/etc. Conversely if I was seeing .90 i would know I was 10% rich from my target.
Here's the basic formula for making corrections when tuning in lambda: (actual Lambda)/(desiredl Lambda)= correction factor
so 1.10/1.00=1.1
or
0.65/0.785= 0.82 or an 18% correction
hope that kinda makes sense as I was typing this up in a hurry while at work... in case anyone was wondering I am an EFI calibrator and tune cars for a living, so feel free to ask any questions.
05-17-11, 03:00 PM
#12
BTW E85 is great stuff... but it's not a wonder fuel. It will still detonate, albeit usually with less catastrophic damage than gasoline as it's BTU count is about 60-70% that of gas. Which is another reason why it takes more fuel t to produce the same amount of power when using E85.
05-17-11, 03:23 PM
#13
if you leave your wideband as if it were running on gasoline you can tune for same AFR's since its just a calculation out of lambda.. i think its easier that way since im used reading AFR's but maybe its just me 
05-17-11, 03:28 PM
#14
I was the same way... but once you embrace lambda it makes life soooo much easier. Most of the tuning I do is flash programming that can;t be done in real time... so having easy math for correction factors is a big time saver. I can set my target lambda to 1.00 for all my part throttle low load stuff and click off a few sampling points and make my corrections super quick.... then go back for a couple WOT pulls and it's done.
05-18-11, 05:35 AM
#16
I won't let go
If this same engine is converted to run on E85 you would use the same lambda values as lambda remains constant. So.... 0.785x9.85 (stoich value of E85)= 7.73 AFR. So.... as you can see E85 is run considerably richer than gasoline. This is largely the reason why converting to E85 requires upgrading the fuel system in terms of both flow and overall capacity. A typical increase of 30-35% is expected when going to E85 from gasoline.
So the above posts claiming 11's and 12's would be crazy lean on E85.... FYI.
So the above posts claiming 11's and 12's would be crazy lean on E85.... FYI.
Point is the lambda is the same, just the AFR reading differs depending on how you display lambda.
So...11.5, with a gas AFR being displayed IS 7.73 on E85, therefore NOT crazy lean. Else, everyone running E85 would have blown up their motors by now.
As I mentioned in another thread, it's much easier to just explain AFR in terms of lambda and NOT in traditional AFR readings.
05-18-11, 04:56 PM
#17
That was the whole point of my post.... it is better to use values of Lambda as they are universal for all fuels. You can't post AFR numbers without knowing the stoich ratio of the given fuel. Any calibrator/tuner worth there salt will tell you this.
Just because everyone leaves there widebands displaying in gas AFR's doesn't mean it's correct. Everyone could light their heads on fire too, but it doesn't mean it's wise. If you' are going to post a recommended AFR you should preface it by saying you are using gasoline AFR's. Otherwise someone like me will tell you your numbers don;t make sense, or worse yet... someone might actually take your advice and run 11.5 on E85 and blow their motor... I know I don't want that on my hands.
Just because everyone leaves there widebands displaying in gas AFR's doesn't mean it's correct. Everyone could light their heads on fire too, but it doesn't mean it's wise. If you' are going to post a recommended AFR you should preface it by saying you are using gasoline AFR's. Otherwise someone like me will tell you your numbers don;t make sense, or worse yet... someone might actually take your advice and run 11.5 on E85 and blow their motor... I know I don't want that on my hands.
05-19-11, 04:28 PM
#18
You're just confusing everyone even more with this. Most everyone leaves their displays as indicating gas AFR (as do I). Most don't change to E85 calibration. That being the case, 11s and 12s are fine. That's what everyone is doing. .785 lambda as you just described is either 11.5 on gas or 7.73 on E85.
Point is the lambda is the same, just the AFR reading differs depending on how you display lambda.
So...11.5, with a gas AFR being displayed IS 7.73 on E85, therefore NOT crazy lean. Else, everyone running E85 would have blown up their motors by now.
As I mentioned in another thread, it's much easier to just explain AFR in terms of lambda and NOT in traditional AFR readings.
Point is the lambda is the same, just the AFR reading differs depending on how you display lambda.
So...11.5, with a gas AFR being displayed IS 7.73 on E85, therefore NOT crazy lean. Else, everyone running E85 would have blown up their motors by now.
As I mentioned in another thread, it's much easier to just explain AFR in terms of lambda and NOT in traditional AFR readings.
JUST USE THE SAME VALUES YOU WOULD WITH GAS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
FORGET ABOUT THE LAMBDA CRAP.
My car runs like a bat out of hell @12;1 AFR'S. No ping whatsoever.
05-17-12, 02:09 AM
#21
Know this is an old topic, but have to post.
I was running my AFR's in the high 11's and a friend told me that was too much fuel.
I leaned it out to around 12.2:1.
My car is a different car! It has way more power and torque.
My friend said you can lean E85 out to about 14:1 without any damage.
He also said running it rich is more harmful than running it lean.
I was running my AFR's in the high 11's and a friend told me that was too much fuel.
I leaned it out to around 12.2:1.
My car is a different car! It has way more power and torque.
My friend said you can lean E85 out to about 14:1 without any damage.
He also said running it rich is more harmful than running it lean.
Car still idles perfect, drives perfect, and pull like crazy! No sign of any damage. E85 is the real deal!!!
Last edited by Neutron; 05-17-12 at 02:12 AM.
05-17-12, 03:06 PM
#22
I am running 30 PSI now @ 12.3:1 (Gas AFR's)
Absolutely no sign of detonation.
I have run 13:1 AFR's @ 25 PSI accidently and it didn't do anything.
I wish I would have converted to E85 years ago when I was blowing engines left and right.
I have been running it for over 2 years with no signs of coorsivness.
I love the stuff!
Absolutely no sign of detonation.
I have run 13:1 AFR's @ 25 PSI accidently and it didn't do anything.
I wish I would have converted to E85 years ago when I was blowing engines left and right.
I have been running it for over 2 years with no signs of coorsivness.
I love the stuff!
