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Gas?

TheOtherNick

TheOtherNick

The mod from over yonder
I have been thinking about it for a while and finally decided to ask about it. Around me I have two different choices for premium. I can get 91 with no ethanol or 93 with up to a 10% ethanol blend. What would be the best to use and what are the advantages to converting to run on e-85?
 


i persaonally dont have 93 around me. must be nice haha. but the advantages have been argued many a time but the way i see it, once do you do the proper modification, with e-85 you get 105 octane, a colder fuel charge, and your engine looks shiney and new thanks to the cleaning properties...i will eventually do this conversion.
 
The advantages of E-85 are like he said. You get a rating of like 105 octane. It's usually cheaper. The dis advantages are you will need to buy 65# injectors, a BAP and a fuel pump for sure. You will also need a tuner or a pcm that has the correct IFR table on it for the injectors.


IMO It's really only worth it if you're going to be doing a lot of modding. And need the advantages of the 105 octane.
 
Well I dont have E85 around me here anywhere near, but Ive been hearing reports that with gas prices as they are now, E85 is not cheaper, but like I said I dont have anything to base that on other than the reports Ive heard on the radio and from others I know.
 
True you're also going to be using 2 times more fuel. So f you're doing it for the price...Don't.
 


Ive never experimented with it, but I have held the belief that while in a modernly produced vehicle that there is going to be fuel economy losses with E85, I think they can be overcome. First and foremost would be to have a PCM that is tuned specifically to run E85. Better yet, have a PCM with two sets of programming in it. One for regular 87, 89, 91, etc and then one to run E85.

The second thing would be to up the compression substantially. The higher the compression the more efficient an engine is. So if you could take the compression up to say 11.0:1 or higher, Im not sure what E85 would support then I believe that you would negate the fuel economy losses or do so to such and extent it would be irrelevant.

Obviously on a supercharged engine the dynamics change a bit and Im not sure what you could get away with as far as compression. I dont plan on going with E85 at the moment but I should have a better idea of some other ideas I have once I get my engine back together that may shed some light on some other techniques that would allow much higher compression.
 
I always thought e-85 was a lower octane fuel, that's why I was not sure of the benefits from it. I seam to lose about 2 mpg's when I run the 93 with 10% ethanol. I tend to just run the 91. I do not have a scanner to check the kr differences between them. I can only scan every now and then at school.
 
Nope, E85 is up there in octane, it just doesnt have the same energy per btu that gas does so your mileage drops.

Also, you loose fuel economy on higher octanes anyway. The primary advantage of higher octane fuel is its slower burning so it controls knock.
 
Yeah I knew the high the octane the slower the burn. I was just wondering what effect the 10% ethanol has, if any? Besides making it cheaper :th_thumbsup-wink:
 
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Its not always cheaper either unfortunately. The 10% ethanol in gas is more of a national fuel saving initiative which I dont completely understand either. 10% less gas but you get worse fuel economy so you end up filling up more frequently. I dunno, but it doesnt seem much like a fuel saving idea to me.
 


I notice the difference between non-ethanol and 10% ethanol. Drops my highway MPG by about 3MPG. Also I'm tuned on non-ethanol 93. When I'm forced to use an ethanol blend my trims go from between -1 to -3 up to +4 to +6. I don't like it.

Also the car just doesn't have as much "oompf". I've been comparing scans and its starting to make sense. The added fuel the PCM has to use to maintain stoich (since the ethanol wants more to burn evenly) affects timing through the mg/cyl tables in the PCM. The more mg/cyl the less timing. Less timing is less HP.
 
And you'd be suprised how many gas stations are using the 10% blend. There are a lot of them switching to that
 
Every where around me has 10% in the 89. It was funny working at a gas station for a while seeing all the people from outta state coming in asking what ethanol is and if they could put it in their car.
 
I think every gas station around here has 10%. I think having about 10 ethanol plants nearby might help.
 


Yeah there is one plant about 5 miles from my house and another two about 30 miles away. I found that the truck stop out side of town has 92 I could never remember what it was. I just plan on filling up there whenever I can. Does any one know about what the Kr difference is between 91 and lets say 92 or 3?
 
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