Summary: Everybody agrees that 0.87 Lambda makes the best power, but if you're possibly using E10 you need to be running 0.82 Lambda for it to be the same, otherwise you're running lean.

So over the weekend, I learned that the Houston area (Harris County and immediate surrounding counties) has a regulation stating that E10 must be at the pumps.

For those that don't know what E10 is, it's a mixture of up to 10% Ethanol mixed in with the gas. The idea is to help emissions, but then again your gas mileage per tank goes down and you therefore burn more... but that's for another thread.

Anyway, stoich for gas is ~14.7AFR. Stoich for Ethanol is ~9.00AFR. That means that stoich for E10 would be (14.7 x 0.90) + (9.00 x 0.10) = ~14.13AFR.

Now in the past, many people have been pressing tuning for 0.87 lambda (0.87 = x / 14.7.... so x= ~12.78AFR) at WOT. That's for gasoline though, not E10. E10 requires lower AFR as seen in the example above. For E10, it would be 12.2AFR (14.1 x 0.87 = ~12.2).

Therefore Vince tunes at 0.82 Lambda for the E10, which is the equivalent for 0.87 Lambda on gasoline, assuming that you'd want to not run lean if you got some E10. Having dynoed his car, he found that this made the most power... but the NW (and the U.S. overall) is increasingly adopting E10, and explains the disconnect. Basically he and the HPT guys running 0.87 lambda agree on ~0.87... but Vince was running it based on E10 (so it ends up being based on a 14.1AFR stoich) and tunes his customers accordingly in case they have E10 in their area or the places they go.

Just thought I'd throw that out there. If the U.S. continues to adopt E10, we may have to start basing our tuning off of a 14.1AFR base instead of a 14.7AFR base.

 

had this discussion with vince last year when I tuned my car and is prob why his hhr pings like a popcorn machine at .87

most of the pumps in my area have a sticker that says contains 10% ethanol. I think it will become more and more common.

 

A lot of info + a lot of numbers and formula's = my head hurts

Some good info there

 

hehe .. good info i'd talked to vince about this a while ago but i got tired of arguing with other people

 

We have E10 in our area and going from .85 to .88 on the dyno net another 20whp. 0 KR and my plugs look they are burning properly....

 

I run a cruise lambda of .977 for the 5.5% Ethanol in my area, but I still run .88 at WOT on 93 octane.

Thanks for your input. Most areas that say up to 10% Ethanol are between 5-6%.

 

Most fuel is ~15% now.

 

Maybe in Cali, not in the midwest.

 

read the plugs. do not assume.

 

Well when I dynoed my car (had it 2-3 weeks) we found it was already tuned! The tuner (Church Automotive in So Cal) is familiar with the SS/TC and had just tuned one THAT MORNING (with mods on)! We found that it was pinging (he heard it) and right off he said *we need to take care of that*. The timing was too agressive (it was an AZ car..maybe that's why?) and he wanted to RICHEN it up too. So here's the before (GREEN) and after (BLUE) AFR's. You can see that he added torque and power lower down as well. Some hear think AFR's are too rich..well, the graphs speak for themselves. BTW it's 91 Octane out here.

 

High 11.x AFR is pretty rich for an LNF, even if running E10.

 

I wonder if he's running that Cali E15 mix that LS1fbody mentioned.





Y'all got me wondering:

Ethanol also allows for more timing by nature, so I wonder how much more timing can be realistically gained by running E10 vs straight 91/93 Octane gas.

 

Youre also comparing changing your lambda AND timing to a previous tune.

 

I wish I understood any of that.. haha.. I even have HPT from my old LS1.. but I bought it just to tune out my O2's and pass emissions.. never learned anything after that

I fail

 

so what is it about an air fuel mixture of 0.87xStoichiometric that allows best power? Is it just safer? I'd assume 1xStoich. would give the most power since you'd be sure to burn all of the fuel?

 

10% in Austin.

 

we have 10% ethanol out here in az

 

Only from November to March and that's supposed to change to November to January.

Currently, I run .86 up top, even with the 10% blend and I show no signs of detonation unless its over 100 degrees. Plugs look good and logs coincide.

 

Stoich actually has nothing to do with power, it is simply the ratio at which the fuel burns most completely. By running a richer fuel mixture the fuel burns faster which creates more power, but only to a certain point. Every car has a different AFR where they make the best power with ideal timing for that AFR and RPM. The LNF, being direct injection, can achieve a faster burn at a leaner AFR due to way it injects the fuel directly into the combustion chamber, while also achieving a better chemical cooling effect then typical port injected engines which also allows a leaner AFR to be run.

 

That certain point it determined by the amount of oxygen there is.

 

Well thanks for the math lesson! I understand what lambda is now, lols. its the percentage change of actual stoich AFR to demanded stoich AFR. So it makes sense that the lambda should be 1.00 is a stock tuned car.

By the way, I think all Wawa gas pumps use E10, they all say contains 10% ethanol. Makes senses my car gets crazy knock every now and then.

 

why not just go ahead and run E85, we've got that stuff all over the place around here and there is not E15 AFAIK... www.E85Mustangs.com is where i learened about all that stuff when i had plans to convert mine.

 

trooth.
thats how he explained it to me when i got my tc.
for safety reasons its best to not blow someone up.

our injectors won't support it

 

plus wawa gas is only 91 as well

 

without bigger injectors, e85 is impossible to run on the LNF. there is just not enough injection window