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View Full Version : 50/50 91 and E85=98 Octane Test (I'm Bored need a new project at its finest)



oldevodude
03-09-2012, 10:49 PM
I'm going to try a 50/50 mix this weekend. Goal is right around 7 gallons each of e85 and 91 which should net right around 98 octane instead of the 105 approx. that e85 is. I started a new contract job that is 70 miles round trip and e85 fill ups and overall mpg made me switch to 91 for a while.Â* Since the difference in fueling is approx. 30% I'm figuring I can have 15% less flow rateÂ* on 98 vs e85 pure or lower fuel volume requirement which will net me around 3-4 more mpg's.Â* Â*I get around 12.5 MPG with E85 and around 17-18 with 91. I know I drive hard and can't stay off the boost so my mpg sucks.
Â* Â*I'm really not sure if it will be do anything other than give me something to fart around with. Knowing the injectors will autmatically adjust trim I'm not so worried about my mixture being super accurate let alone perfect scaling although it will be interesting to see if the injector scaling comes out right in the middle of the E85 and 91 maps and how much more timing I can run than 91 or relatively speaking how much timing needs to be removed fro mthe e85 map. My thoughts are I'll still be able to run 30-32 psi and make power.

Hopefully at minimum I'll get off my lazy ass and at least6 fill up with E85 and start dialing in the injectors and initial testing this weekend. If people post I'll know there is interest and post findings.Â*

I'm also hoping for $5-$8 a tank savings which adds up when you are filling up more than twice a weekÂ* :'( And yes I have money and can afford the car so let's not go thereÂ* ^-^

Cool calculators that offers good estimate for mixing fuels and costs associated

http://www.serioussolutions.com/evo/octcalc.htm
http://www.bazellracefuels.com/Calcs/OC1.htm


PS this might have already been done and if so share results or even race gas lower octane to 91 comparo will offer relative data

http://forums.evolutionm.net/evom-newbie-faqs-forum/308218-fuel-tank-capacity.html

http://www.bazellracefuels.com/Calcs/OC1.htm

blkside
03-10-2012, 05:49 AM
Thats cute and all... Make sure you post the thread where you blow your engine up.

Have you ever asked yourself why ALL tuners tell you to run the tank dry before swapping maps... think about it for a minute.

cbell386
03-10-2012, 07:52 AM
Before putting it in your car I would mix the two fuels and let it sit for a while, just to see if they separate at all. With e85 being a lot thicker it may not blend so well and may separate from the 91 causing you to get all of one fuel first. Do baby steps, maybe not half and half at first, but start with 10 to 1 gallon, tune it for that, then 9 to 2.. just a idea good luck and hope everything works out

cbell386
03-10-2012, 07:55 AM
But I still don't think its a good idea.. like blkside said, there is a reason all tuners say to completly empty your tank before making a switch... I wouldn't recomend trying it. To much could go wrong in your car...

leetEVO
03-10-2012, 08:55 AM
Have you ever asked yourself why ALL tuners tell you to run the tank dry before swapping maps... think about it for a minute.


I'm going to go on a limb and say... they were doing a straight gas or e85 tune... :-P He can run just about anything he wants as long as he has a tune for it.

Most gas has a % of ethonal in it anyway.... what your're worried about is really phase seperation.. this can happen in ALL gas... depending on conditions.

blkside
03-10-2012, 09:08 AM
@leetevo - you are wrong sir.

E85 requires more fuel in the combustion chamber hence the reason you burn through it quicker. You dont mix the 2 because they burn at different rates. Either he is going to have to scale the injectors for a 91 tune and run it lean as shit or he is gonna have them scaled for an E85 and wont save any gas but effectively lower his octane rating for no reason.

I think its funny you mention how "I can afford my Evo" but you apparently cant afford gas.... just a thought

amaev05
03-10-2012, 09:23 AM
he can afford the gas. but needs a bigger tank. i think.

WilsonEvo8
03-10-2012, 09:59 AM
I think he can try what ever he wants lol it his car and we will see what happens. Also I think he said he can afford gas but just wants to get a little more out of the tank.

oldevodude
03-10-2012, 05:52 PM
@leetevo - you are wrong sir.

E85 requires more fuel in the combustion chamber hence the reason you burn through it quicker. You dont mix the 2 because they burn at different rates. Either he is going to have to scale the injectors for a 91 tune and run it lean as shit or he is gonna have them scaled for an E85 and wont save any gas but effectively lower his octane rating for no reason.

I think its funny you mention how "I can afford my Evo" but you apparently cant afford gas.... just a thought


Leet is right. Why do you think those race gas vendors have calculators that calculate blends of fuel.Â*

How many 91 pumps have you seen with stickers that say "may or Contains Ethanol"Â*
Here is another link that speaks in favor of MTBE over Ethanol in our pump gas and the fact that our 91 has ethanol in it already and up to 10%
http://www.calgasoline.com/factetha.htm


Here is Wiki talking about common Eblends and my mix comes in at around E44

http://en.wikipedia.org/wiki/Common_ethanol_fuel_mixtures


E85 as the name implies is 85% Ethanol and 15% Gas alreadyÂ* You are right and in my post I said E85 requires more volume and it happens to be 30% give or take.Â* The tuners will get more fuel to the engine by changing injector scaling to tell fuel system to pump 30% roughly more fuel and yes this is why you don't get so many miles per tank. In the case of a 50/50 mix of e85 and 91 the difference is simply right in the middle and any one who has tuned knows how to check fuel trims and fine tune from there.

To address the mixing issue simply think of all the factory flex fuel vehicles out there. They are designed to run on any mixture of gas or e85 in any combination. They do this by having an ethanol content sensor that feeds the ecu and fueling is adjusted. I'm doing the same thing.

Part of affording a car in my opinion includes the cost of driving it.Â* All I'm doing is conducting an experiment really and thought I'd share but some can't open up their minds let alone do research to see if it is possible prior to saying things that simply aren't true.

FWIW I put 7 gallons of e85 in as I had remaining 91 already in the tank and then topped off with 91.Â* I performed initial fueling changes to pump more than 91 but less than e85 and will check trims to see how close I am on adjustment. I have map switching so switched to the E85 timing but haven't really got on it yet.Â* AFR is the same as e85 and idle AFR 14.7 is also the same.

In other states they have Winter blend and Sell E70 instead of E85 to help winter startup what happens to all those Flex fuel cars not to mention tuned cars on E85?

PSÂ* All gasonline sold in America has Ethanol in it due to federal law passed during Busch administration.

oldevodude
03-10-2012, 06:29 PM
Thats cute and all... Make sure you post the thread where you blow your engine up.

Have you ever asked yourself why ALL tuners tell you to run the tank dry before swapping maps... think about it for a minute.


I don't need a minute to think about it.In fact it makes me wonder how many people go so far as to have let alone watch a wideband to know when to switch maps after changing fuel and how many conider the old fuel type is in their lines and rail for a few minutes and the fact you should def. drive easy after changing from 91 to E85 especially.
The tuner wants the most e85 in there as possible as it is more agressive tune and you'll knock if not enough ethanol content when switching from E85 to 91. 91 to E85 not as important other than fuel trims and too much fuel until 91 gets burned away from lines and rail.Â* Â* Â* Â* Â*

It is all cute to the point where you think about the fact you can't run your tank completely dry when switching fuel types as there is always fuel remaining in the tank of whatever type of fuel you are switching from right?Â* Â*When peeps go get tuned the tank is not completely dry of one type fuel is it?
The injector trims can compensate for this adding or subtracting or fuel. assuming your injectors are scaled properly . I know you know this right?Â* I'm betting you also know it takes 2-3 tanks after switching to get all the 91 out and have pure e85 which is 15% of 87 or so octane anyway right?Â* Â*LOL think about it why would I try this if I didn't have half a clue of what I was doingÂ* let alone share it on this board knowing that a lot of posts get shit on any way


Â* Â* Â*PSÂ* Â* Â*If/When my motor blows I will be sure to post but it won't be due to this experiment.

oldevodude
03-10-2012, 10:14 PM
Go read this article on Injector Dynamics website ... It might surprise you that e85 sold could only contain 50% ethanol anyway.

I know you have an ethanol content analyzer like i do right? They are available on the web for pretty cheap.

I actually have two of them but really don't have money for gas LOL


Here is some verbiage from the link

Are you sitting down?

The original specification set the minimum ethanol content at 75% which was lowered to 68% in June of 2010, and lowered again to 51% in June of 2011. As of February 2012, this is the current specification and E85 purchased from the pump could have an ethanol content as low as 51% and still be within spec.

So now that you know the what, you're probably interested in the why. At least I hope you are. You didn't come here with a blank stare and drool running down your face expecting to see how many people "liked" E85 did you?

2. Monitor the ethanol content of your fuel. This can be done one of two ways. Either install a fuel composition sensor, or measure it directly using the "baby bottle method" which is detailed at the end of this article.

3. Tune conservatively. Knowing that the octane value of the fuel can change even if the ethanol content remains constant, you will be wise to leave a few hp on the table by keeping that final 2 degrees of advance to yourself.

http://www.injectordynamics.com/AlcoholArticle.html

Go Read knowledge is power

cbell386
03-11-2012, 06:57 AM
This conversation is way above my level lol... My question is though, since you will have to tune for whatever blend you are running, how will you keep it at that mixture? Wouldn't it be more of a list to be constantly mixing fuel to try to keep it right around the same level? Wouldn't you need to keep a decent amount stored? Wouldn't it be easier just to run 91 then when you wanna go for the weekend fill her up with e85? Or have you considered running meth instead?

Skiracer
03-11-2012, 07:31 AM
Guys on EvoM are working on a patch where they use Zeitronix's Ethanol Content Analyzer output signal to adjust the Evo's ECU's mapping depending on the ethanol mix. If this does work, i'd say this is the only safe way to run a 50/50 mix. Otherwise, its like guessing what mixture of fuel/e85 you have in your tank

http://forums.evolutionm.net/alternative-fuel/421070-ces-eth-content-sensor-installed-flex-fuel-patch-coming-soon-10.html

oldevodude
03-11-2012, 11:15 AM
This conversation is way above my level lol... My question is though, since you will have to tune for whatever blend you are running, how will you keep it at that mixture? Wouldn't it be more of a list to be constantly mixing fuel to try to keep it right around the same level? Wouldn't you need to keep a decent amount stored? Wouldn't it be easier just to run 91 then when you wanna go for the weekend fill her up with e85? Or have you considered running meth instead?


Â* Â* Â* Â* Â*I'm tired of running straight 91 so I'm trying a blend. What people don't get is by design all modern cars inherently adjust fuel trims or fueling based on a lot of factors but the bottom line is the Factory ECU can and does adjust for fuel differences be it 91 e85 or whatever in between including different blends by adjusting the fuel trims. Knowing the injectors can automatically adjust 15% and up to 25% measured by Evoscan I personally know I'll be ok. I simply put the scaling inbetween e85 and 91 tune and will monitor to see how close my scaling is. As long as I fill with equal amounts of 91 and e85 moving forward I'll be ok.
The manufacturers program ability to change for fuel differences to compensate for different types or batches of gas . I have watched my fuel trims change via logging by using straight e85 for over 2 years and you can see differences in batches causing the injectors scaling or fueling to vary quite a bit. I have also measured differences of over 10% in E85 content from same station by using the "poor mans ethanol content analyzer"Â* See my threadÂ*

http://forums.evolutionm.net/alternative-fuel/397007-poor-mans-ethanol-content-analyzer.html

Look at page 2 in the link and you'll see a huge variance in Ethanol content at 2 stations
What is even more sad is same thread was posted here and the difference is astounding in how the information was/is received on either forum.
I kinda knew how the thread might turn out here and maybe that is part of the overall experiment but figured I'd try to share with the LOCAL community regardless:)

So does everyone know or change tune when fuel varies? the answer is no but the ECU can and does accomodate for this.Â* The Injector Dynamics article points out to leave a couple of degrees of timing on the table to prevent knock to compensate for fuel differences and the ECU handles the rest. We also assume or insure our injectors are scaled properly to allow the ECU to adjust for us

Regardless I guess the point of forums is to share ideas and experiences and I guess that is getting accomplished regardless of whether or not people understand or agree.Â* Party on GarthÂ* :)

blkside
03-11-2012, 11:21 AM
Im well aware of the ECA,its been around longer than a week.... Look at your original post. Its a "Im gonna mix 2 different gas and see what happens durka durka"

I never said it wasnt possible but the way you were talking about going about it, wasnt gonna happen.

And as far as running a tank dry, Im well aware that there is residual fuel in the lines as well as the sump. You are looking at a 14 gallon indicated tank with about 1.2 galins in the sump and lines. If you run it until the light comes on and for a few minutes afterwards, when you fill up the residual fuel is negligible and wont make a bit of difference. Ive been running E85 for a while and I switch at the track so Im aware of the repercussions.

And there have been plenty of people who have come on here saying they knew what they were doing. Matter of fact one guy tried to explain his brother was a fuel expert. he turned out to be the guy that fills the stations.

Good luck with this... hope you save a few bucks but I drive my car like a retard and like the extra octane. As a matter of fact Ive had 2 tanks of 91 in the car since I switched to E85 a few years ago. No guessing mixtures for me.. 100%=100%

oldevodude
03-11-2012, 11:51 AM
http://img41.imageshack.us/img41/9342/e85comparison.jpgÂ* yeah 100% is not 100%Â* Durka Durka Â* Â*


I guess Durka Durka menas you are actually trying to post a halfway intelligent thread on SoCalEvo?Â*

I like to drive hard too.... so much so that I'm trying to get a littleÂ* power back since I switched from e85 to 91
I can run straight up E85 but simply want to see how much power is lost going from straight E85 to 99 octane.
This will give me some or most of the fun/power of e85 but a little more range for my long commutes. I'm lazy and used to work 1 mile from e85 stations now there are 2 roughly 8 miles from my house.

I can't help but think you are missing the whole point as to some people experimenting and trying different things is actually fun.

oldevodude
03-11-2012, 01:28 PM
Back on Topic Driving home from fuel station and letting the car idle for a while the Fuel trims are as follows....
I peddled it and was running 91 timing to avoid detonation or knock as it is commonly referred to.
Short term Fuel trim is -2.5
Mid Fuel trim is -5

Right now It's getting slightly too much fuel and the ECU is pulling volume away to compensate. I changed the global a little to pull in mid trim and will start boosting to see how much timing needs to be pulled due to lower octane. To be safe I'm starting with 91 Ignition map and going up from there.

If anything comes from this at minimum I'll have a 100 octane map that will allow me to run 100 octane RaceFuel in my car. I'll use 91 fueling and ignition map that gets built from this experiment.
One of the beauties of the Evo is that it is so easy to change fuel relative to an old school carbureted vehicle.
People used to think I was crazy for running Methanol let alone Alcohol straight up on a street car.

It was fun to shoot flames, esp. at night due partly to carbureter inability to control fuel like more modern cars.
Yeah Fun this why most of us do it right?
Times haven't changed with respect to people but technology sure has :)
If you don't have anything good to say it's easier to keep it to yourself and it's pretty obvious why this board doesn't have many technical discussions like others.
It is a free speech board though so I'm just "sayin".

amaev05
03-11-2012, 05:41 PM
i know exaxtly how you feel. :coolsmiley:

blkside
03-11-2012, 09:18 PM
Im not missing the point. I completely understand where you are going with this but I think this falls under the work vs reward theory.This is a lot of effort to have a mid point in performance. I think the experiment is great if you have an end goal. I will see what you and the EVOM guys come up with but as a whole, are you willing to do this all the time once its figured out?

Good luck with it...

oldevodude
03-12-2012, 09:14 AM
Well yeah it does seem like a lot of work but for someone who plays on computers all day long it's not too bad. Once it is dialed it won't be too hard to pump 91 and e85 at close to the same amounts and be safe knowing trims can compensate but in the end I'm not really sure how much I'll run it but I can say based on limited testing that it beats the hell out of 91 with respect to performance although not done testing let alone dialing it in.

I'm going to check out how the new ignition maps apply to straight up 100 pump next likely ,,,if tune is near edge on e85 the pump 100 octane will knock due to less combustion cooling properties of std. AV or 100octane fuel vs. e85/91 I haven't confirmed but I'm betting the 100 octane will be well over 8 bucks a gallon but offer closer 91 octane mpg. Not a dollars thing per se but if at the track I assume you might want to run cheaper fuel esp. if it works better then cost becomes added benefit not primary reason for running a prticular fuel ;)

I'm spending money to run a tank of 100 octane and this will be over $100 so money not the issue here never was primary I simply hate to pump gas every couple days even when I drove a motorcycle I hated it . I'm a lazy bastard thats why i do computers for a living

AlphaKennyBody
03-12-2012, 09:27 AM
IMO, I don't think you'll gain too many miles for it to be worth doing a 50/50. I mean it's your "project 50/50 mix" and you free to do what you will but just saying I can't grasp to understand why even do a 50/50 just for the mileage and have SOME power behind it.

You established that multiple stations have different content which I discovered this weekend between Norwalk vs Beaumont vs Sacramento/North Highland.

You would have to sit at the pump and keep an eye on exactly how much fuel you adding.....

Anyways keep us updated O0

oldevodude
03-12-2012, 04:42 PM
yeah it sucks when you get a bad tank of e85 which is why I typically and always try to carry laptop to change tune to compensate for bad fuel. Yeah I know it's a pain but I believe totally worth it given the state of tune our cars are in and how far from stock they are. When I grow up I'll put a car-puter in there LOL
The 50/50 is actually pretty easy although filling up to full will be a problem. for example at half tank add 3 gallons each of E85 and 91 and the mix will stay although tank won't be full. Like I said this is an experiment and not a long term thing. My plan is to buy some 100 octane Race Fuel after this tank or two and fine tune for that and be done but have the 100 0ctane map available if the need/desire arises in the future.

blkside
03-12-2012, 07:14 PM
If y our E85 tune isnt on the ragged edge, then it wont be too serious.. I gotta get retuned for the mods I have changed.... I never have my tune "hail mary" for numbers

oldevodude
03-12-2012, 11:13 PM
totally agree I tune way conservative cuz i don't want to blow up and I can be anal when it comes to computer related stuff. I haven't really touched tune in most a year and I haven't changed any parts either. I'm down on power regardless right now as my TB seals are leaking and sadly can't find the ones Aby gave me a long time ago so gotta buy more.

HB Alex
03-14-2012, 08:30 AM
i didnt think you could mix the two fuels because they are different densities? gotta be careful about mixing fuel, might end up blowing out your engine. saving a few bucks in the short run is nice, but if you ending up having to replace parts gunna be way more expensive :/

kambodianboi
03-14-2012, 08:36 AM
i didnt think you could mix the two fuels because they are different densities? gotta be careful about mixing fuel, might end up blowing out your engine. saving a few bucks in the short run is nice, but if you ending up having to replace parts gunna be way more expensive :/
You can mix fuels no problem, just the ECU have to be adjusted for it.

oldevodude
03-14-2012, 05:27 PM
Have to Understand by Default E85 is a mixture by default E for ethanol and 85 for supposed 85% and 15% unleaded gas.

Anyway I'm 3/4 tank down and 150 miles in. Fuel trims are right around 2.5% and I could adjust further but I'm happy with it. Car is much faster than 91 and closer to e85 straight up than 91. Surprisingly timing is not really retarded too much. I'm guessing I'm right around 25-35HP down from E85 and up around 30 from 91 once again just guessing but can definitely feel difference throwing out the "placebo" effect. Time permitting maybe I'll do some VDR stuff but I really don't rely on those as your numbers can vary day to day on the same road by 25+ HP. I can say that fuel settings in tune are pretty much right in the middle of the 91 and 105 scalings.
Boost is right around 29psi and timing is down a couple degrees in the middle of the rpm range and while I believe the car might run the same timing up top I pulled it back just in case O0 Sadly it's rare but I'm on overtime and next day off is Sunday so if I get around to more datalogging or formal pulls I'll post more data although this tank will have run dry and not sure if I'm going back to straight e85,91 or continue the 50/50 experiment.

PS Wiith the right tune it is my opinion this is actually as safe if not safer than 91 due to higher octane and greater ethanol content which inherently offers cooler burn and cooler combustion temps.

Cheers

AlphaKennyBody
03-15-2012, 02:04 AM
O0 Good Stuff! Interesting..... Lets see those Logs!

kambodianboi
03-15-2012, 09:51 AM
Hows the consumption of fuel. As E85 requires 30% more than 91oct. Your mixture should consume about half of that, right?

oldevodude
03-19-2012, 11:04 PM
Hows the consumption of fuel. As E85 requires 30% more than 91oct. Your mixture should consume about half of that, right?


15% or yeah half the 30% difference of 91 compared to e85 and yeah mileage or range was up by 15-20% due to less fuel requirement and surprisingly power was good. I'm back on 91 as I wanted to wait for light to come o nand fill up so I could see how many miles driven vs. how much to fill up. it was roughly 190 miles driven for 12.6 gallons of fuel. This is right at 15mpg when I usually get right around 12.5 on e85 and if I'm lucky 19mpg on 91. I know my numbers might seem low but I drive super hard and can't stay off boost.

I can say the experiment did what I expected and I have a decent 100 octane map in case I want to do it again. I'm leaving map in for now to fill up soon for another 50/50 mix. now that 91 is back in it's 7 gallons e85 and the remiander 91 will get back to close to 50/50 mix.