E-85 Questions And Advice

[sascraggs]

I have a 2007 GMC Yukon With the 5.3 Flex Fuel and I have run E-85 in it a few times in the past. In the last month I have been filling up with it every time. Basics are the fuel prices especally duing and right after the hurricane in Texas, but also it seems to give my truck more power and it runs better on it. My main question is do I need to be adding an additive to the fuel system on fill ups or every so often? I am sure that thier is some draw back to the ethanol I know that it will eat rubber lines etc. I run royal purpule oil and stock fuel system filter etc. any advice or experince will be greatly appreciated. This is a great web forum.

 

Thanks

 

SAS

[redvett]

Read your owners manual, no additives are needed. E-85 vehicles are engineered for them to run without any problems.

 

I have a 2007 GMC Yukon With the 5.3 Flex Fuel and I have run E-85 in it a few times in the past. In the last month I have been filling up with it every time. Basics are the fuel prices especally duing and right after the hurricane in Texas, but also it seems to give my truck more power and it runs better on it. My main question is do I need to be adding an additive to the fuel system on fill ups or every so often? I am sure that thier is some draw back to the ethanol I know that it will eat rubber lines etc. I run royal purpule oil and stock fuel system filter etc. any advice or experince will be greatly appreciated. This is a great web forum.

 

Thanks

 

SAS

[HawkeyeOC]

Have fun with E-85, it should give you a little more power

 

The main drawback to E-85 equipped vehicles is more frequent trips to the gas station, price in some areas and availability.

 

Just don't put that stuff in a non-E85 equipped vehicle...it will eat it alive

[Nick The Great]

What they said.

 

I've run 99% E85 in my truck since I got it in March. I'm lucky in that in Iowa we have it at a lot of stations.

 

When I checked it in April, my city driving commute got me 13.5 mpg. Same route on E85 was 11mpg.

[neto1978]

What they said.

 

I've run 99% E85 in my truck since I got it in March. I'm lucky in that in Iowa we have it at a lot of stations.

 

When I checked it in April, my city driving commute got me 13.5 mpg. Same route on E85 was 11mpg.

 

Mine is doing 10 mpg on city too!!! but the ethanol here in brazil has 8% of water on its composition.

[fbachman]

Well, given that the LHV (Lower Heating Value) of E85 is on the order of 20%-25% LESS than that of gasoline, the mileage decrease is well within the expected decrement.

 

That's why ya have to be careful regarding the economics of E85. Depending on the price difference, it may, or may NOT, be cheaper to run than Gas.

 

During the $4+/gallon area I did a study and found that at a gas price of $4, E85 had to be almost a $1 less per gallon to break even at 20,000 miles per year (soemthing like that if I remember correctly),

 

Now, given that gas in many parts of the country is now hovering in the High $1 to mid 2$ range, it makes E85 all but uneconomical to run in every sense.

[Nick The Great]

Well, given that the LHV (Lower Heating Value) of E85 is on the order of 20%-25% LESS than that of gasoline, the mileage decrease is well within the expected decrement.

 

That's why ya have to be careful regarding the economics of E85. Depending on the price difference, it may, or may NOT, be cheaper to run than Gas.

 

During the $4+/gallon area I did a study and found that at a gas price of $4, E85 had to be almost a $1 less per gallon to break even at 20,000 miles per year (soemthing like that if I remember correctly),

 

Now, given that gas in many parts of the country is now hovering in the High $1 to mid 2$ range, it makes E85 all but uneconomical to run in every sense.

 

You seem pretty knowledgeable on this subject.

 

I've often wondered, if to be fair, I ought to compare the price/mileage of High Octane gas, 93 to the E85. I mean, the octane rating of E85 is 105 or so. Does that mean that comparison would be more fair?

 

In all honesty, I've never run 0% ethanol. Most of the gas in Iowa has at least 10% in it. You can get it, but it is usually 10 cents more expensive than the 89 Octane, 10% Ethanol. I imagine I'd get a hair better mileage then, but surely not enough for 10 cent/ gallon.

 

Just curious.

[iminaquagmire]

I have a 93 octane performance tune from Justin at Blackbear so my experience is a little different, but if you have a tune, its something to keep in mind. Though it is only my experience.

 

That said, I've been running E-85 for the last 4 tanks now and have gotten 12.2mpg versus the 13.1 I got with 93 with 10% ethanol. E-85 runs about 30-35 cents cheaper here, so its barely worth it cost wise if you use 87. However, after switching from 93, E-85 makes a huge cost savings. Plus my truck runs the same if not better, and to top it off, E-85 is a much cleaner burning fuel.

 

I don't think E-85 is the fuel of the future by far, but it works great for me now.

[fbachman]

Well, given that the LHV (Lower Heating Value) of E85 is on the order of 20%-25% LESS than that of gasoline, the mileage decrease is well within the expected decrement.

 

That's why ya have to be careful regarding the economics of E85. Depending on the price difference, it may, or may NOT, be cheaper to run than Gas.

 

During the $4+/gallon area I did a study and found that at a gas price of $4, E85 had to be almost a $1 less per gallon to break even at 20,000 miles per year (soemthing like that if I remember correctly),

 

Now, given that gas in many parts of the country is now hovering in the High $1 to mid 2$ range, it makes E85 all but uneconomical to run in every sense.

 

You seem pretty knowledgeable on this subject.

 

I've often wondered, if to be fair, I ought to compare the price/mileage of High Octane gas, 93 to the E85. I mean, the octane rating of E85 is 105 or so. Does that mean that comparison would be more fair?

 

In all honesty, I've never run 0% ethanol. Most of the gas in Iowa has at least 10% in it. You can get it, but it is usually 10 cents more expensive than the 89 Octane, 10% Ethanol. I imagine I'd get a hair better mileage then, but surely not enough for 10 cent/ gallon.

 

Just curious.

 

 

The octane rating of the fuel measures its ability to RESIST detonation. Having a higher octane fuel would ALLOW an engine to be more agressive with timing and compression ratio as the higher octane prevents/resists the onset of pre-ignition.

 

It becomes a question of whether the timing tables are set up to take advantage of the additional octane available.

 

Case in point: If you have an engine set to run at a nominal timing strategy that allows good drivability, without knocking, on 87 octane, and you then fill up with 100 Octane aviation fuel, your engine will see NO benefit in terms of power, UNLESS to jack the timing to be able to take advantage of the higher octane.

 

IMHO, if you are tuned to run 93 octane, and take advantage of it in the timing tables, and run 93 consistently, then, yes, the FAIR comaprrisson would be a cost/mile calculation between 93 and E85.

 

As you boost ethanol content, your mileage will decrease, as you are dropping the LHV of the fuel as the ethenol content increases.

 

THis is why I don't understand the "Ethanol" push. Yes, it's renewable. BUT, it takes more energy than is contained in a gallon of gas to produce a gallon of E85. Without tremendous subsidies, E85 will never be more economical than gasoline.

 

In Europe, the HEAVILY subsidize E85 (Bio Fuel they call it there). Only then can it be economical for the vehicle operator--- but in the larger control volume, everyone loses. Rather than paying directly at the pump, the fuel cost is split between tax payer $s to the Govt and tax payer $s at the pump. The perceived economic benefit is more psychological, than real.

 

The mileage benefit of higher octane gas is, again, a direct result of the ability to juack timing to get a more efficient detonation, potentially at a high compresison ratio as well. Only, the higher CR would require an engine mod. Thus, we're left with timing. Again, so long as your pooter can move the timing around enough take advantage of the better fuel properties, you may see a (very) slight mileage boost, but at a simultaneous drop in LHV of the fuel.

 

That trade will absorb the fuel economy benefit VERY quickly over the decrease in LHV. It's all a physics based shell game. No free lunch (unfortuneately)

 

 

Nitwittery.

 

[Nick The Great]

Interesting, Grumpy Aero. Thanks for responding.

 

I'm going to the Minnesota tune this weekend. I'm anxious to talk with Justin and see what he can do and recommend with all these different octane fuels.

 

[Bowtie2Sierra]

THis is why I don't understand the "Ethanol" push. Yes, it's renewable. BUT, it takes more energy than is contained in a gallon of gas to produce a gallon of E85. Without tremendous subsidies, E85 will never be more economical than gasoline.

 

In Europe, the HEAVILY subsidize E85 (Bio Fuel they call it there). Only then can it be economical for the vehicle operator--- but in the larger control volume, everyone loses. Rather than paying directly at the pump, the fuel cost is split between tax payer $s to the Govt and tax payer $s at the pump. The perceived economic benefit is more psychological, than real.

 

+1

[fbachman]

Interesting, Grumpy Aero. Thanks for responding.

 

I'm going to the Minnesota tune this weekend. I'm anxious to talk with Justin and see what he can do and recommend with all these different octane fuels.

 

 

 

Not a problem. I would be very interested to see what his take is on it. What I do NOT know, is whether a tuner exists that can dynamically adjust the timing tables based on the fuel. I believe the ECMs control that via the knock sensor, and PULL OUT timing if knock is detected. What I do NOT knopw, is if that process could be pushed the other way, i.e. pushing timing UNTIL knock occurs, then backing off a little to protect the engine. Then, you are taking FULL advantage of the fuel's capabilities.

 

Would be VERY interested in knowing that.

[RyanbabZ71]

I have run E-85 100% of the time since I bought new in Feb. I am averaging about 13 mpg about 70% city driving in my 08 2wd Tahoe. Its gets about the same milage as my 00 5.3 Z71. Oh yea E-85 was $1.41 today