My E85 as a Octane Booster Experiment
05-20-2010, 09:58 AM
#1
Safety Car
Thread Starter
My E85 as a Octane Booster Experiment
Just thought I'd share this in case it can help someone.
I have a heads/cam LS6 with a 12:2 compression ratio in my vette. For the last few months Ive been messing with it here and there trying to see how much timing I can put into it without detonation or pinging. Well, Im in CA so 91 pump gas sure doesnt help. My first idea was a methanol and water injection system. I pieced one together with a Snow Perf pump and a Summit RPM window switch. It worked good but on hot days I still noticed some lugging when loading up 4th on the frwy
(its an A4), like partial throttle at highway speeds. Now with 100 octane being $7.99 a gal I didnt want to spend $120 on a full tank of gas so I did some research on e85 which I knew was about 105 octane. A few problems arose, first, what was the availability of e85 and, what mods are needed to run e85?
First, CA sucks at e85 availability but luckily for me theres a Chevron with e85 three blocks from my house. Still, I didnt want to be dependant on one gas station with the nearest one being in Beverly Hills 45mi away. So I decided, based on octane calculations, to use a 30% mix of e85 to 91oct. This would yield me an octane of about 95.4 which is more than enough for my application and the percentage of e85 wouldnt be too high so that I can fill up with all 91 if I had to and the car would only run a bit rich but it wouldnt hurt anything.
Then, what would I need to run e85? NOTHING. If your car is newer than 1988 I wouldnt worry about corrosion problems. Methanol is the alcohol that eats everything up not ethanol, you'll be fine. All i had to do was richen the fuel. Since I have bigger injectors, it took about a 5-7% increase in fuel throughout the fuel curve. The AFR at WOT is now 12.5-8, right on the money for this percentage of ethanol.
Results, well I havent put it on a dyno but idle feels a lot stronger, it revs up quicker and pulls like a freight train up top
. I have it at 26* of timing right now which is quite a bit for this high of a compression. So far Im very happy but I have yet to drive it more and go to the 1/8mi track next week. So, if youre close to an e85 station and youre a FI or high cr N/A car you should really consider using e85 even if its just as an octane booster. Theres some info on full e85 conversion but almost nothing on partial percentages like myself and on how to tune them. Its a learning process but just experiment till you get the right AFRs and you can add more timing with no detonation problems. E85 is good stuff, safe, clean, creates more torque and cost 40% of race fuel. To get 95.4 octane I use 10.5gal of 91 to 4.5gal of e85. 15gal for a full tank equal $46, cant beat that. 
I have a heads/cam LS6 with a 12:2 compression ratio in my vette. For the last few months Ive been messing with it here and there trying to see how much timing I can put into it without detonation or pinging. Well, Im in CA so 91 pump gas sure doesnt help. My first idea was a methanol and water injection system. I pieced one together with a Snow Perf pump and a Summit RPM window switch. It worked good but on hot days I still noticed some lugging when loading up 4th on the frwy
(its an A4), like partial throttle at highway speeds. Now with 100 octane being $7.99 a gal I didnt want to spend $120 on a full tank of gas so I did some research on e85 which I knew was about 105 octane. A few problems arose, first, what was the availability of e85 and, what mods are needed to run e85?First, CA sucks at e85 availability but luckily for me theres a Chevron with e85 three blocks from my house. Still, I didnt want to be dependant on one gas station with the nearest one being in Beverly Hills 45mi away. So I decided, based on octane calculations, to use a 30% mix of e85 to 91oct. This would yield me an octane of about 95.4 which is more than enough for my application and the percentage of e85 wouldnt be too high so that I can fill up with all 91 if I had to and the car would only run a bit rich but it wouldnt hurt anything.
Then, what would I need to run e85? NOTHING. If your car is newer than 1988 I wouldnt worry about corrosion problems. Methanol is the alcohol that eats everything up not ethanol, you'll be fine. All i had to do was richen the fuel. Since I have bigger injectors, it took about a 5-7% increase in fuel throughout the fuel curve. The AFR at WOT is now 12.5-8, right on the money for this percentage of ethanol.
Results, well I havent put it on a dyno but idle feels a lot stronger, it revs up quicker and pulls like a freight train up top
. I have it at 26* of timing right now which is quite a bit for this high of a compression. So far Im very happy but I have yet to drive it more and go to the 1/8mi track next week. So, if youre close to an e85 station and youre a FI or high cr N/A car you should really consider using e85 even if its just as an octane booster. Theres some info on full e85 conversion but almost nothing on partial percentages like myself and on how to tune them. Its a learning process but just experiment till you get the right AFRs and you can add more timing with no detonation problems. E85 is good stuff, safe, clean, creates more torque and cost 40% of race fuel. To get 95.4 octane I use 10.5gal of 91 to 4.5gal of e85. 15gal for a full tank equal $46, cant beat that.
05-20-2010, 10:27 AM
#2
From my 01' Owners Manual:
Your vehicle was not designed for fuel that
contains methanol. Don’t use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn’t
be covered under your warranty.
Not sure I would even use E85 in a car not designed for it (i.e. designed as a flex fuel vehicle) and it typically get's about 20% worse mileage too. Why not just thy a bottle of octane booster with a tank for low-midgrade?
Your vehicle was not designed for fuel that
contains methanol. Don’t use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn’t
be covered under your warranty.
Not sure I would even use E85 in a car not designed for it (i.e. designed as a flex fuel vehicle) and it typically get's about 20% worse mileage too. Why not just thy a bottle of octane booster with a tank for low-midgrade?
05-20-2010, 11:38 AM
#4
Burning Brakes
I mix ethanol 25-30 % by volume on 93 octane and the Z06 loves it.
I got larger injectors but still need to finish the tune.
There is a lot myths and fears about ethanol, whatever? Its a great high performance fuel!
I use to race with alky and it was also a great race fuel, but I think the ethanol is better, the alky pluses without the issues.
05-20-2010, 11:49 AM
#5
From my 01' Owners Manual:
Your vehicle was not designed for fuel that
contains methanol. Don’t use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn’t
be covered under your warranty.
Not sure I would even use E85 in a car not designed for it (i.e. designed as a flex fuel vehicle) and it typically get's about 20% worse mileage too. Why not just thy a bottle of octane booster with a tank for low-midgrade?
Your vehicle was not designed for fuel that
contains methanol. Don’t use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn’t
be covered under your warranty.
Not sure I would even use E85 in a car not designed for it (i.e. designed as a flex fuel vehicle) and it typically get's about 20% worse mileage too. Why not just thy a bottle of octane booster with a tank for low-midgrade?
05-20-2010, 11:59 AM
#6
Safety Car
Thread Starter
Lol, I know. Most people dont realize that your gas already contains at least 10% ethanol in most places and its possible that itll be up to 20% soon as well. People complain of power loss with the 10% but thats because the more ethanol your gasoline contains the more fuel you need to burn. Since I dont drive my car for mpg reasons I"ll take the extra hp anyday. BTW, I still get 24mpg with my big cam and 12:1 cr. I love fuel injection.
05-20-2010, 04:08 PM
#8
depends on your power level, you'll need to tune the car to have it run correctly. Several places are doing flex-fuel type tunes, and lots are offering full e85 tunes for maximum gains.
05-21-2010, 02:16 PM
#9
Safety Car
Thread Starter
My fuel system is stock except for 36lb injectors which I had to support my existing mods. Just have to tune for the right afr according to the amount of ethanol in the fuel.
05-21-2010, 03:26 PM
#12
Safety Car
Thread Starter
Simple math. E85 is 85% ethanol or 108.8oz to 19.2oz of 91 in a gallon.
So, if you have a 15gal tank, 30% e85 mix would be 4.5gal of e85 to 10.5 of 91.
4.5gal of e85 is 3.825gal of pure ethanol. (4.5x0.85= 3.825)
3.825gal is equal to 25.5% of 15gal (15x0.255= 3.825)
Therefore a 30% mix of e85 with 91 pump gas is equal to 25.5% pure ethanol in your fuel tank.
So, if you have a 15gal tank, 30% e85 mix would be 4.5gal of e85 to 10.5 of 91.
4.5gal of e85 is 3.825gal of pure ethanol. (4.5x0.85= 3.825)
3.825gal is equal to 25.5% of 15gal (15x0.255= 3.825)
Therefore a 30% mix of e85 with 91 pump gas is equal to 25.5% pure ethanol in your fuel tank.
Actually they do have kits to test for certain alcohols in your fuel.
05-21-2010, 03:40 PM
#14
Tech Contributor
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St. Jude Donor '09-'10-'11
Simple math. E85 is 85% ethanol or 108.8oz to 19.2oz of 91 in a gallon.
So, if you have a 15gal tank, 30% e85 mix would be 4.5gal of e85 to 10.5 of 91.
4.5gal of e85 is 3.825gal of pure ethanol. (4.5x0.85= 3.825)
3.825gal is equal to 25.5% of 15gal (15x0.255= 3.825)
Therefore a 30% mix of e85 with 91 pump gas is equal to 25.5% pure ethanol in your fuel tank.
So, if you have a 15gal tank, 30% e85 mix would be 4.5gal of e85 to 10.5 of 91.
4.5gal of e85 is 3.825gal of pure ethanol. (4.5x0.85= 3.825)
3.825gal is equal to 25.5% of 15gal (15x0.255= 3.825)
Therefore a 30% mix of e85 with 91 pump gas is equal to 25.5% pure ethanol in your fuel tank.
05-21-2010, 03:43 PM
#15
Tech Contributor
Haha....just kidding. But on a serious note. The mixtures make sense, provided the fuel is premixed. So my question is, how do you obtain an homogeneous mixture between the two tanks....provided you add the fuels separately?
05-21-2010, 04:05 PM
#16
Melting Slicks
I did a research paper in college about e85 ethanol. in my research i found a group that ran e85 in a completely stock late 90's chevy tahoe. they drove the car for 100k miles and disected the fuel system. they found that the fuel system had less corrosion and was cleaner than every other tahoe they inspected with similar mileage that used regular unleaded.
05-21-2010, 09:53 PM
#17
Safety Car
Thread Starter
05-21-2010, 09:54 PM
#18
Safety Car
Thread Starter
I startedalmost empty and filled up with half a tank and by the second day I felt a big difference. Then I filled up again and in the last 3 days it has been consistent.
Last edited by C5Natie; 05-21-2010 at 09:56 PM.
05-21-2010, 09:59 PM
#19
Tech Contributor
Drive a few days as you tune. Use up half a tank and fill it up. Eventually youll have the same percentages in both tanks.
I startedalmost empty and filled up with half a tank and by the second day I felt a big difference. Then I filled up again and in the last 3 days it has been consistent.
I startedalmost empty and filled up with half a tank and by the second day I felt a big difference. Then I filled up again and in the last 3 days it has been consistent.
05-21-2010, 11:10 PM
#20
Drifting
Member Since: Sep 2008
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E85 is awesome....
Its like running racing gas all the time. More timing, cooler intake charge and more HP. No detonation period...ever...So you gotta be careful as you can run way too much timing as you will most likely never see any knock with it looking at the logs.
Its like running racing gas all the time. More timing, cooler intake charge and more HP. No detonation period...ever...So you gotta be careful as you can run way too much timing as you will most likely never see any knock with it looking at the logs.