I have decided to take the plunge into the wonder that is 105 octane E-85 fuel. I have all the basic bolt-ons plus HKS 272 cams, Buschur 780cc injectors, and a White Rabbit Turbo. This morning with about 1/4 tank I filled up with E-85 (10 gal) and rescaled my injectors from 713 to 550. My short term fuel trims are around -6 to -8, so I may have scaled the injectors a bit too small, but that may also be due to the remaining 4 gal of 93 octane in the tank.

Normal driving feels about the same. Car started fine, drives fine, idles fine. I did a couple of WOT pulls and did not have any knock on my normal 93 octane tune. With the rescale I was around Lambda 0.74 at WOT, which should be good for E-85. After a tank or two I will try running some more boost and reporting back with my results. I also keep detailed records of my fuel mileage and will report back on that as well.

-Paul

 

thats super rich for E-85. E-85 has a high resistance to knock, so use it and run the car a bit leaner. you make more power running leaner, or at the very least turn the boost way up. i would run E-85 from .8-.85 lambda.

 

Great info, thanks for being the test dummy.
Keep us posted.

 

Im intersested in the E-85 also. Is it like running meth?

 

I would start by reading this first, very carefully.

http://knowmore.org/index.php/E85

 

Actually, it's right in the safe range for good power. Max power rich for E85 is 0.7143 and max power lean is 0.8673, so I'm towards the rich end of the max power range. For comparison, max power rich for gasoline is 0.8503 (12.5:1) and max power lean is 0.900 (13.23:1), so I feel pretty comfortable with where the tune sits as it is. Once I run a full tank through and feel comfortable with where things are I will start cranking up the boost. I will also be using DataLogLab to compare power output at the same boost level and at increased boost levels. I almost wish I could get through the fuel faster so I would have the results now.

-Paul

 

your wrong with your numbers. cause .8673 lambda on e-85 is still very rich. with 1.0 being stoichometric ratio, .86 is not at all lean.

 

I have done a lot of research on E85 prior to making this decision. I will be checking my fuel lines, gaskets, and fuel tank fairly regularly. The one thing that may cause some issues is cold-start with 100% E-85. I may need to do a bit of mixing to get it to start on cold mornings.

-Paul

 

Every source I have looked at lists the same information. According to every source, 0.7143 is richer than the max power mixture but will provide within 1% of max power and 0.8673 is leaner than the max power mixture but will also provide within 1% of max power. I certainly do not feel comfortable making it leaner just because you say 0.8673 is very rich on E-85.

-Paul

 

0.7143 & 0.8673 are those numbers for NA or turbo cars?

Fuel AFRst FARst Equivalence Lambda
---- ----- ----- Ratio -----
================================================== =======================
Gasoline stoich 14.7 0.068 1 1
Gasoline Max power rich 12.5 0.08 1.176 0.8503
Gasoline Max power lean 13.23 0.0755 1.111 0.900

================================================== =======================
E85 stoich 9.765 0.10235 1 1
E85 Max power rich 6.975 0.1434 1.40 0.7143
E85 Max power lean 8.4687 0.118 1.153 0.8673

 

The numbers are the same for both NA and turbo cars. Gasoline will make more power at 12.5:1 than it will at 11:1, but 93 octane pump gas does not have the knock resistance to do so. 104 Octane racing fuel, however, can be run at 12.5:1 without issue and will produce more power than it would at 11:1. I plan to stay towards the rich end of the "max power" range and slowly start increasing boost and monitoring knock.

-Paul

 

Its still leaner than one would tune..

E85 has other properties that you benefit from, where it may not be as necessary to tune as rich as you would with Gasoline...

But until many of us are doing it.. I think your better off being conservative and making it a bit richer than leaner for optimum power..

 

subscribed

 

well having already built and tuned an e-85 race car, we ran .8-.85 very effectively. any richer then that was down on power, and ran very poorly. go ahead and try running .71 lambda, but you are seriously missing out on the potential the fuel has. FYI, we had a 11.5:1 compression ratio running 10-14 psi boost with no intercooler on e-85 at .8-.85 lambda... if thats not pushing the limits then tell me what is oh and the car made 73hp from 250cc of displacement. it was a 4 cylinder 16 valve engine too. revved to 20k rpm.

 

Isn't that only 20 ft-lbs of torque then? I think your getting your high HP numbers because of the 20K RPM. At 7500 RPM, that's only 27HP.


Eric