higher octane level from the ethanol, but the ethanol doesn't have the same energy output as unleaded gasoline. you must burn more e-85 to produce the same power as normal gasoline.

strange but true...you can cut your normal mileage by 25% or more when you use E-85

 

Yes, ethanol is a higher octane fuel but it does not create more power. Octane is actually a measure of resistance to combustion. The higher the octane the slower (and thus more controlled) the combustion process. Cars that require higher octane fuels usually have higher compression ratios (such as a lexus)to make up for the resistance. However, ethanol does not have the same BTU rating that regular unleaded has, meaning you get less power out of a like volume of ethanol than you do unleaded.

 

Well mostly...octane rating is specifically "a measure of the fuel's resistance to autoignition" or " a measure of the anti-detonation qualities of the fuel" It does not describe any other quality of the fuel - ie energy content, flame speed, combustion efficiency, ease of ignition with a spark, etc.

For example diesel fuel wold have a very low "octane rating" - it is specifically designed to ignite under high compression conditions, but it has more energy density than gasoline and a slower flame travel speed - most diesel engines rarely turn faster than a couple thousand RPM's.


Higher octane generally allows higher compression ratio which results in more efficient combustion. If an engine were specifically designed for E85, some of the lower energy content could be offset by increased combustion efficiency due to higher compression allowed by the 105 octane. But for most of us using 'flex fuel' it will mean a decrease in efficiency. But the ulitmate measure for me is really 'dollars per mile'. I don't really care if I get 10MPG or 20MPG as long as the 10MPG fuel is at or less than 1/2 the cost of the 20MPG fuel.

 

I just found this E85 Conversion Kit website: <!-- www.************.com --> Removed. My 07 F150 is flex fuel from the factory, but the wife's isn't. It's nice to know there is an option besides paying $3.31/gal! E85 is going for about $2.40 in Denver. Athough my F150 gets slightly less mpg on e85, it runs a lot better and has more power, and I still save money overall.

The kits go for 400-500, so it doesn't seem like a bad deal.

 

I’m pretty sure they aren’t legal in the US. If you modify a truck like that you have to prove that the emissions are as good or better then stock, which from what I hear is difficult if the vehicle wasn’t designed for it from the get go.

 

But if it doesnt affect how the truck runs on regular unleaded, and E85 is supposed to cut emission by about 50%, who's gonna complain?

 

in the websites FAQ section it says they're legal to run in the US

 

If that device is working on the same principles as others I have seen it is basically just intercepting the signal to the fuel injector and making it a bit longer.

The one main problem with E85 in a non FFV is that most non-FFV vehicles are programmed to set a Check Engine Light if the fuel trim exceeds some nominal value....say +/-20%...meaning that the computer is having to put in or take out an additional 20% fuel from what is programmed. Under normal driving on normal fuel this condition wouldn't happen unless something was wrong with the engine - hence the CEL.

Running E85, the computer will compensate based on O2 sensor input, but the trim may go beyond the software coded trim limit and set a CEL. The box makes the fuel injector pulse width is artificially longer, then the computer thinks it isnt putting in as much fuel and will stay below limit coded to set the CEL.

Too bad there isn't some way for the every-day Joe to do that without spending $500!

 

another thing to consider is that E-85 is corrosive. the FFV motors have different seals and can handle this. the fuel delivery system is also built to wishstand the corrosiveness.

I'm sure the interceptor system works, but it seems easier and safer to buy a FFV vehicle than to try and convert a non FFV vehicle.

 

I emailed the company that makes the conversion about that issue and tis is what they said. I am not sure they are being 100% honest with me.


Those articles are correct, but their findings do not apply to most vehicles, only old vehicles. The gas tanks, fuel lines, pumps and injectors they say need to be replaced were phased out in the 80's. The truth is that any car on the road today can run E10 (10% ethanol) with no problem (it's in 75% of super unleaded and few people even notice), and all the additives already in gas are so corrosive that E85 really isn't that much more corrosive. E85 will clean out the deposits left by gas in your fuel tank and lines, which is why we recommend changing your oil and fuel filters after running E85 for about 625 miles. After that you will experience a cleaner, better running, longer lasting vehicle

 

E85 is now .90c Cheaper than 87 octane gas....i'm running E85....screw the middle east

 

Ohhhh, I notice the 10% ethanol. My gas mileage with it is never as good as it is without it.

 

Would it be safe to run a half E85 half regular unleaded tank of fuel? It would atleast saving some money without too much compromise of economy and power?

 

Yes, your engine control computer with adjust for any level of mixture between unleaded and ethanol.

 

I see one myth here that needs to be addressed. That is:

"Ethanol makes less power than gasoline because it contains less energy."

If both fuels were run at the same air-fuel ratio, then yes, the ethanol would make less power. But this is never the case in a well-tuned FFV.

Stoichiometric ratios:
Gasoline (100% iso-octane): 15.2:1
Ethyl alcohol: 9:1
E85: 9.93:1

Energy content, in BTU/LB:
Gasoline (100% iso-octane): 20,750
Ethyl alcohol: 13,160
E85: 14298.5

So it would look like E85 makes less power, right? Wrong. Take a look at what happens when we figure in the air/fuel ratio, to figure energy released at stoichiometric mixtures:

Gasoline: 20,750 / 15.2 = 1365.13
Ethyl alcohol: 13160 / 9 = 1462.22
E85: 14298.5 / 9.93 = 1439.93

So we can see that running at stoichiometric ratios, ethanol and E85 do release more power.

Now lets look at the ratios at which each fuel makes maximum power:

Gasoline: 12.5:1
Ethyl alcohol: 6.5:1
E85: 7.4:1

Now lets figure up how much energy is released for each fuel:
Gasoline: 20,750 / 12.5 = 1660
Ethyl alcohol: 13,160 / 6.5 = 2024.62
E85: 14298.5 / 7.4 = 1932.23

So at the ratio at which they make maximum power, ethyl alcohol and ethanol blended fuels come out on top. I hope this puts and end to the debate as to what makes more power in an FFV.

Throw the high octane into the mix, and you could run a high compression engine on these ethanol fuels and make even more power, and raise the efficiency. Of course, then you lose the ability to run gasoline. But you would get your mileage back, plus you'd be making a whole lot more power!

To me, ethanol and ethanol blended fuels are clearly superior to gasoline.