E85 afr?

[slo265]

Hi Guys just new to forum but have been playing with E85 for a couple of months now and are stumbling into a few problems.

I have a 4.3 litre straight six with a turbo gt42 blow through CSU carby (Built for blow through).
No matter what I do to the rear I can not get the AFR lower than 12.5 on it. I made 580 hp at the wheels on 18 psi with this AFR.

I keep getting told that E85 reads differently but then others say that you should tune it in the 11's?? What do you guys tune yours to?
I know a lot will say lambda or you read plugs etc but I read mine of AFR and surely this is too lean?
Help
Thanks

[lt1camaroman93]

I tune to .875 lambda if memory serves me correctly.

[slo265]

Are you sure that sounds quiet lean from what I am getting told to tune E85 on. That equals about 12.90 AFR is that right?

[lt1camaroman93]

0.82 Lambda with race-gas is 12 real AFR (14.7 * 0.82). With E85 the "real" AFR is (9.7 * 0.82) = 7.92 AFR

I could be mistaken though. 1.00 lambda is stoch no matter what the fuel if I'm not mistaken. All I know is I'm yet to hurt a plug and I've made over 100 passes with ~1000hp on tap.

[slo265]

Thanks so I should tune it to Lambda then to be safe. What is rich and what is lean with E85 on this.
Can Anyone else tell me what they tune there to?

[drag chevette]

tune .87 at idle,
tune .82-.84 at cruise,
tune .77 at wot.
blower or turbo cars can go as low as .72 but i like to keep it around .74 on the supercharged stuff.

[72much1]

I'm using the AEM Air fuel gauge and I run mine between 11.3 and some times as high as 11.8 on a mild tune.

All ways read the plugs to be sure. E85 can be hard to read at times.