Given that most of today's gas is now E10, should we be tuning to a richer AFR to support the Ethanol in the gas? My understanding (very limited) is that Ethanol has extra oxygen and therefore makes the AFR even leaner(about 3-4%).

So from my reading, stoich on 100% gas is 14.7 and E10 is roughly 14.2. So my question is - is this correct? If it is then we now know why our stock HDs are running really hot.

Another question. If we have a tuner like Thundermax or SERT, couldn't we modify the maps basically make our HDs E85 compliant? If we richen up & change the timing enough?

Just throwing out a few stupid questions before I go riding this weekend.....

 

It's my understanding the Stoich is 14.68 with todays fuels however I don't know a thing about E10 and E85 fuel terms.

 

E85 is a corrosive and non-effecient (Economy wise) fuel when used in an E85 (Flex-Fuel) vehicle....

It is far more than modifying a map in the ECM... It is the fuel lines, filter, engine internals, calalytic convertor, etc.....

The sensors in a flex fuel vehicle determine what type of fuel is being used and modify the PCM accordingly... Kinda like having a Dual mapped ECM...

As far as the Stoich comment... If you have EVER seen the evolution of HD Racing maps (SERT/SEST/V-Tuner) you will see that as the maps evolved through the years, they were leaned out a bit, but as soon as the NBo2's were installed in the system, it was a requirement to have the LIGHT/NO-Load portion of the map lean..... But that portion of the map is NOT FELT at idle or WOT.... Only at cruise..

Those portions of the maps are anywhere from 12.5-13.8.... Not all, but most....

Larger displacements, catalytic convertors, lousy fuels are all contributing factors to the heat issue....

 

Thanks Bob...I did a serch on the web and found the E85 and E10, I understand what it is now....DUH!!!! LOL..LOL..LOL

 

I found this formula on a car performance forum:

The formula for blending two fuels and finding their stoic is as follows:
(stoic point fuel #1 * % by mass)+(stoic point fuel #2 * % by mass)


stoic point of gas = 14.7
stoic point of ethanol = 9

87 Octane with 10% Ethanol blend (90 gas, 10% ethanol)
(14.7 x .90)+(9 x .10)= 14.13 Stoic AFR

 

This is a repost From Silver States Stangs Mustang Club From Dyno Dan who Works For Dynojet


For those of you concerned with ethanol blend fuels, and what the effects are, I'm going to provide some insight.

Petrol fuel has a stoich of 14.7, while ethanol has a stoich of 9.0. When you blend 10% ethanol with 90% petrol, you end up with a fuel that is quite prevalent in the marketplace, it's called E10 or "gasohol". Now, without spending 3 days going into detail, I'll answer the question that is bound to be asked, "what does this do to my tune". Well IF you're truely running E10......read what the state had to say to me:
>>
Dan,
The fuel in Las Vegas is a botique fuel in the winter, but not in the summer. There are 4 E-85 stations in Las Vegas and Rebel fuels some times runs gasohol year around, but it is based on cost. To get our exact fuel formulation you need to get in touch with Vernnon Miller at the State Department of Agriculture.
Peter Konesky
>>

So in the winter months (not sure which months are considered winter months), we're all getting a "botique fuel", better known as E10, but depending on the price, Rebel stations (and probably others) will have E10 potentially year round.

So, back to the question, "what does it do to my tune"? Well, let's look at an example. Since Dynojet dyno AFR equipment reads lambda, and then calculates and displays petrol AFR, we'll say your car is tuned for 13.0 AFR under high load / high RPM. If the fuel is actually a full petrol fuel, this value of 13.0 is legit, and the lambda value is .89. Now if you were running E10 (even if you didn't know it) and your friendly Dynojet operator says your car is tuned and running at 13.0, that's wrong. To get back to .89 lambda (lambda is independent of fuel type), you'd have to have the car tuned to 12.57. 12.57 AFR, as reported by Dynojet AFR equipment (which is scaled for petrol) would get you back to a lambda of .89 while running E10.

Now you may ask, "well it seems that if my tuner just tuned the lambda to .89, everything would be perfect", and that's correct, but the Dynojet AFR equipment and software display petrol AFR, not lambda (that's changing). This still doesn't account for the fact that if you're switching between E10 and petrol, with or without knowing it, then your tune needs to be changed, that is if you think 1/2 point variance is important, which for some of you on the ragged edge, it could be.

The tuning associated with correcting for E10 fuel is easy to do, the biggest issue is knowing if you're actually running a blended botique fuel / E10.


Assuming the components in your fuel system can withstand E85, which they should, then you really just need a tune. In regards to the tune, it's actually quite simple to change the calibration to accomodate for E85, but you need to be aware of a few things:

- You'll need roughly 30% more capacity in your fuel system (injector / pumps). Depending on where you're at now with power, you may or may not have enough capacity. Based on your sig, your car should make 410 rwhp, and the stock pumps and injectors will get you out to 460-470 actual rwhp. That being said, we'll have to keep an eye on your pump and injector duty cycle.

- You'll need to change the fuel filter after a few hundred miles of running E85

- There are only a few pumps here in town that actually carry E85, and the analysis of the E85 will vary between 3-10%. Since the analysis of the fuel is inconsistent, the the stoich value is inconsistent, which in turn will yield inconsistent AFR's (between 3-10%).

- Unless the E85 prices have gone down dramatically, you'll be no further ahead in cost savings over petrol. You'll drop about 15-18% on your MPG as compared to petrol.

* if you're all good with this, then you can take advantage of E85's higher octane with a tune that will allow more timing, and