E85 Tuning

[It Will Run.Maybe]

I have a 5.3 bored to 5.7l. Gen3. LS6 intake, summit stage 2 8707 camshaft, DBC, 1 7/8 headers 3 inch out. Got 12613412 50lb injectors and aem 30-0300 wideband should be here by the weekend. I downloaded a 2002 tahoe flex fuel file and tried to modify as a start file.I want to be able to run and switch between pump gas and E85 like the factory vehicles with flex without having to change my tune between each. I have searched forums but cant find a clear answer. How do i tune for both? Do i have to start with pump gas in my vehicle tune it and then switch to E85 and tune a different section? Any help and clearification will be great.

[It Will Run.Maybe]

i am assuming all you have to do is tune EQ ratio with premium gas installed and EQ ratio alcohol with E85 in take?premium vs e85.png

[blindsquirrel]

The factory vehicles have a alcohol sensor and automatically blend depending on the %. Have you installed a sensor? It's not enough to just flip the flex enabled/disabled switch, there is no flex without the sensor on Gen 3s.

[anniversaryss]

Although I've tested mine in varying conditions in open loop my AFR seems to stay pretty good between 93 and and flex blends and flex sensor

[It Will Run.Maybe]

i have component sensor 13577429 installed

[Alvin]

I have a 5.3 bored to 5.7l. Gen3. LS6 intake, summit stage 2 8707 camshaft, DBC, 1 7/8 headers 3 inch out. Got 12613412 50lb injectors and aem 30-0300 wideband should be here by the weekend. I downloaded a 2002 tahoe flex fuel file and tried to modify as a start file.I want to be able to run and switch between pump gas and E85 like the factory vehicles with flex without having to change my tune between each. I have searched forums but cant find a clear answer. How do i tune for both? Do i have to start with pump gas in my vehicle tune it and then switch to E85 and tune a different section? Any help and clearification will be great.

Before you get too far with this.

E85 will make power over 87 octane in this application.

I doubt it would make power over 93 in this application. With 93 on this setup you can basically put so much timing in it will loose power before showing knock.

There are really good applications for E85 like boosted stuff. This really isn't one..especially for all the complication.

[It Will Run.Maybe]

There are several reasons why i wanted to be able to use both. 1st is E85 is $2 gallon cheaper than 93. (In NC i can get E85 for less than $2 gallon and 93 is over $4 gal.) As long as i am driving around my my state i should be able to find E85 pretty easily. If i am driving out of state, not sure how hard it will be to find E85 so i would like to have the option of running 93.

[SiriusC1024]

I find it simpler to tune airflow and spark with pump gas then re-enable the Flex logic.

E30-E40 is the perfect medium. That equates to 91-93 octane. Factor energy density into the price. Blending e85 with 87 is the most economical, at least here in IN where e85 is only 20 cents cheaper than 87.

Watch the Flex spark corrections when you get done tuning. You might not get knock, but don't tune like that. Don't exceed MBT. MBT will be a few degrees lower than stock with your setup btw.

[kingtal0n]

There are several reasons why i wanted to be able to use both. 1st is E85 is $2 gallon cheaper than 93. (In NC i can get E85 for less than $2 gallon and 93 is over $4 gal.) As long as i am driving around my my state i should be able to find E85 pretty easily. If i am driving out of state, not sure how hard it will be to find E85 so i would like to have the option of running 93.

Alcohol fuel is not cheaper than pump gasoline. It is cheaper per gallon but the fuel economy is so much worse you will spend more money using alcohol.

Alcohol is a racing fuel. Very clean, smells great. I highly recommend it for keeping the engine clean. Just don't expect better economical use of $$ per miles.

[SiriusC1024]

Alcohol fuel is not cheaper than pump gasoline. It is cheaper per gallon but the fuel economy is so much worse you will spend more money using alcohol.

Alcohol is a racing fuel. Very clean, smells great. I highly recommend it for keeping the engine clean. Just don't expect better economical use of $$ per miles.

Ugh maybe smells ok out of the pump. Out the exhaust without cats it's terrible. One of the constituents of the exhaust from running E is acetaldehyde.

[TheMechanic]

A reduction in mileage between 15-30% is typical for the switch to E85. Typically E85 at least in my area is about half price. Current price for 91 octane here in SoCal is $6.29 to $6.99. Regular 89 is about 20 cents cheaper. E85 I have seen just yesterday as low as $2.81. So at least in my area it can be a substantial savings to use E85 on stock through whatever.

[kingtal0n]

I never gave much thought to making acetaldehyde at combustion temperatures without a silver catalyst.

Interesting right
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3713400/

Acetaldehyde occurs naturally in ripe fruit, coffee, and fresh bread, and is produced by plants as part of their normal metabolism.

https://www.legacygt.com/topic/39025...d-cons/page/3/

e concluded that total
toxic compound mass emissions are likely to increase,12,15
but potency-weighted toxicity will be reduced.

DOI:10.3155/1047-3289.59.2.172


Acetaldehyde is a natural product of ethanol metabolism in the body via alcohol dehydrogenase.
If you drink any kind of alcohol beverage you've been exposed to more blood bourne acetaldehyde than I would think any number of inhalations of E85 fuel burning could provide.


Introducing my favorite picture


Yeah it be like that

[SiriusC1024]

It also naturally fucks you up. Pretty sure it's a carcinogen. Go take a sniff of E exhaust. It'll make your eyes water and give you a headache fast. I'm not even sensitive to that kind of stuff, but it makes me regret not having cats sometimes.

[kingtal0n]

Just drink more alcohol until the thought dies with the brain cells that came up with it

[SiriusC1024]

As you can see, there is substantial acetaldehyde production. Here it's illustrated. Exhaust content decreases as the catalytic converter warms up.
acetaldehyde.png

https://www.sciencedirect.com/scienc...17305598#f0010

It's even worse on a cammed motor.

[kingtal0n]

I have so many tuned alcohol engines and their owners insist it smells great. We've run those cars in somewhat enclosed garage spaces without a second thought.
I never noticed anything odd or got a headache.

alcohol is much cleaner than gasoline, you can tell just by its structure and limited reaction coordinates.


I am not sure those measurements indicate production without catalyst. I wonder if the cats are producing alcohol metabolic products as unburnt alcohol is passing through when cold.

I always tune the alcohol engines lean though- 15's. Just like gasoline. This would naturally produce fewer unreacted product and more CO2/H2O I would guess. Fewer partially reacted products.

Acetaldehyde is an ethanol which has been attacked by an oxygen radical at the mid carbon. Not nearly as reactive as formaldehyde of course but those exposed electronegative resourceful region of electrons could form an unwanted bond- nevertheless the fact that alcohol produces this product naturally in the body and so many people drink alcohol kind of sets my mind at ease with respect to the sheer volume of exhaust gas and mole fraction of acetaldehyde being produced with or without a catalyst.

Drink more worry less ;D

[SiriusC1024]

Those measurements were obtained from a running engine. The results pertain to Euro emissions standards. ~10 milligrams/second is quite noticeable. Eyes will water in one sniff I promise. I'm not talking suck on the pipe. I'm talking "waft it" like you would do in the lab.

I will say methanol exhaust smells good. Not that that is an indicator of it being healthful for you. Burning that stuff doesn't produce acetaldehyde.

[kingtal0n]

Those measurements were obtained from a running engine. The results pertain to Euro emissions standards. ~10 milligrams/second is quite noticeable. Eyes will water in one sniff I promise. I'm not talking suck on the pipe. I'm talking "waft it" like you would do in the lab.

I will say methanol exhaust smells good. Not that that is an indicator of it being healthful for you. Burning that stuff doesn't produce acetaldehyde.

Avoid methanol at all costs. Methanol will produce formaldehyde - a fixative we use for tissues and cell samples, when it contacts human alcohol dehydrogenase. Very powerful carcinogen and useful for dead bodies only. Do not breath it. Do not touch it. I warn all of my new phd students and all of my interns on the first day about the dangers of methanol and to be careful not to mix bleach with alcohol because it can kill you and most people have both of those things at home.

Some hand sanitizers accidentally put methanol in their products (search it up) and sometimes they are contaminated with it by accident. Be careful where you get sanitizer.

[JayRolla]

Alcohol fuel is not cheaper than pump gasoline. It is cheaper per gallon but the fuel economy is so much worse you will spend more money using alcohol.

Alcohol is a racing fuel. Very clean, smells great. I highly recommend it for keeping the engine clean. Just don't expect better economical use of $$ per miles.

I usually make out pretty good with e85 over premium. I have paid $2.69 per gallon this year when premium was in the $4.50 range. Even right now with premium at $3.84/g, e85 is still over 30% cheaper. I get exactly 28% less fuel mileage currently on E and thats with very aggressive driving.

[kingtal0n]

I usually make out pretty good with e85 over premium. I have paid $2.69 per gallon this year when premium was in the $4.50 range. Even right now with premium at $3.84/g, e85 is still over 30% cheaper. I get exactly 28% less fuel mileage currently on E and thats with very aggressive driving.

Maybe. In order to properly calculate mileage your speedo would need to be calibrated well. Then you would need to know exactly how many gallons of fuel you burnt, which can vary pump to pump because of how they shut off sometimes. Whether you are willing to let some fuel spill out the side of the car rofl.
Plus the added cost of driving to a E85 station if you can't find one quickly when the tank is low
I mean, a percent here, there, ____

With
-fill full tank at specific pump to absolutely full
-drive exact miles
-fill full again and calculate mileage per gallon

Then do it 3 or 4 times like that. You can generate enough data to perform student t-test and see whether there is a significant difference.

You might be onto something given the crazy prices of gasoline.

There are a couple potential drawbacks to using alcohol fuels in some fuel systems, it is an incredible solvent. It can corrode metal inside the fuel tank if it has access to atmospheric oxygen. It may contain biomass and clog filters. It can dissolve crud in the tank from years of gasoline and clog like that too.
Everyone I know uses it without having these issues. I am sure you are aware. I Just like to provide all the necessary considerations. e.g. if you are only saving 2% fuel cost but risking the fuel system and potentially clogging filters and injectors, is it worth it? If you are turbo then absolutely