You're correct on this. The E10 blend is an attempt to reduce carbon monoxide emissions. If you can keep the fuel mixture at its stoichiometric air/fuel ratio, those (and other) emissions are reduced or eliminated, and you wouldn't need the 10% alchohol.

The thermal BTU rating is simply one way of rating the energy potential of fuel. It's true that heat itself is not what produces power in an engine, but heat causes the fuel mixture to expand as it burns, and the expansion is what produces power. 100% gasoline DOES have more energy potential than E85.

We really can't take full advantage of the octane rating of E85, since we can't adjust the compression ratio. About all we can do is advance the spark. If an engine was designed to burn only E85, it should perform better using it than our flex-fuel engines.

I'm with you on the correct use of corn alcohol, fordmaster - it belongs in a glass!

- Jack

 

Sounds like its time to find me a straw and drain my tank

 

Friendly correction...it belongs in a JAR...I'm in Arkansas!

 

More power from E-85?? You may need to get your butt dyno recalibrated.

 

For those of you who had input with substance, thank you!

 

One of the few reasons I dislike Florida...mandated E10 in ALL stations

 

I thought that the compression was dropped to decrease pinging...

 

You MAY be getting mixed up by two different things here.

I'm older than dirt, so I grew up in a time when engines ran on leaded gas and by adding lead (Tetraethyl lead), engines could be made to perform more powerfully and efficiently. One characteristic of Tetraethyl, is that it raised the octane rating of gasoline, which refers to the resistance of gas to "pre-ignite" (ping) under compression, so that made engines with very high compression possible. Lead made it easy to achieve octane ratings of 100+. Lead also lubricated the piston rings and cylinder walls.

Unfortunately, Tetraethyl is extremely toxic, so in the 70's it was phased out (within just a few years, actually) and engines had to be redesigned with lower compression engines. Those higher compression engines still on the road either had to be reworked to lower compression or the owners had to hope that the lead substitutes that were available could keep them running. I think Amoco was the first to produce an unleaded high-octane gasoline, and other refineries followed suit. But, unleaded gas did not have nearly the detonation resistance of the leaded stuff, and the really high compression engines of the old days got phased out. I tried using Amoco in my Mercury 429 CID engine - it didn't work at all.

Today, almost all engines are designed to burn 87 octane. So, they have relatively low compression. A few are designed for the higher octane stuff, and their compression ratios are somewhat higher.

High octane gas is not better, it just doesn't ignite as easily and it has a more controlled burn (push on the piston).

- Jack

 

In a kind word, no. Lead, as it was in gasoline formulations back in the day, was a wearing agent, not a lube as such. It worked great on keeping valve seats from receding though. But lead in gas caused tremendous wear at the rings, cylinders, and bearings. That's one of the major reasons we went from seeing engine life of 60-75,000 back then miles to well over 200,000 miles now.

BTU (British Thermal Unit) defined: A BTU is defined as the amount of heat required to raise the temperature of one pound of liquid water by one degree from 60° to 61°Fahrenheit at a constant pressure of one atmosphere. It is also considered as 1.06 joule which equates to right at 780 ft lbs of force or 3/4 Newton or Kip prox.

 

You *ARE* getting more power on E85. The less "energy" per gallon is being completely compensated for by the O2 sensors, which are sending signals to dump more fuel in. This is also why the mileage sucks. The additional power comes from the knock sensor allowing more timing advance due to the higher octane.

If you look at the specs for the 09 5.4, it's got higher torque and HP ratings on E85 than gas. The earlier FFV's are not separately rated like that, but the concept is the same. Ford simply advertised the E85 ratings prominently on the 09's because they are falling farther and farther behind the competition in numbers.

 

Very nicely stated Labnerd! I agree, I was confusing the effect on valves with the effect on cylinders and such. I knew there was SOME beneficial effect, but I got it wrong! :o Thanks for correcting me.

Yup, and this equates to energy, doesn't it? A BTU is equivalent to 780 ft lbs of torque (or moment). Kindly right back at you, "ft-lbs" is not "force", but I'm not trying to split hairs.

- Jack

 

Uh, no, that's not what I said. 780 ft lbs of force...not torque. Ft lbs is defined as: A unit of work equal to the work done by a force of one pound acting through a distance of one foot in the direction of the force.

Cumon' J&J, I don't have anybody to nit pick with anymore. They keep sayin' I'm some kinda plethora or sumthin like that. I think maybe thems fightin words but I can can't find my map to look it up.

 

Okey-Dokey, I see the definition of "force x distance" seems a bit fuzzy in the "literature". But, I ask you, how can "force" be the same as "force x distance"? Force is a "derived" value, equal to mass times the acceleration due to gravity. Now, if you multiply that by a distance measurement, it becomes something else, right?

That's all I was saying, and, I was trying to "save face" for printing such an outrageous statement as "lead lubricated the pistons". :o

You corrected me rightly on that one. But, I was just "pinging" you on a technicality. No harm, no foul - I THINK we're both on the same page here.

- Jack

 

And now I'm going to take you on, glc, since I did such a pathetic job with Labnerd. (Are we having fun yet?)

I DO agree with what you are saying. You are dead right. But, I think you are saying something that is potentially confusing.

The O2 sensors quite obviously DO dump more fuel in if you are burning E85. The stoichiometric A/F ratio of ideal "gas" (n-heptane, iso-octane) is 14.7. The stoichiometric A/F ratio of E85 is about 9.765. And, the O2 sensors WILL attempt to maintain this A/F ratio to promote efficient fuel burning. This means you need to increase the fuel flow (if you use E85) by 25-30% per intake stroke. It's not rocket science to see that this translates to fewer miles per gallon of fuel.

And yes, the anti-knock sensors will allow the spark to be advanced to take advantage of the higher octane rating.

Now, do you get more force per cylinder charge? Maybe - I haven't thought that through, so, you may be correct here. Maybe, just maybe, you CAN accelerate faster from a standstill using E85 than I can using straight gasoline. And if so, it's because there is 25-30% more fuel in the cylinder charge than I have with real gas and you've advanced the spark (and this all makes up for the lower BTU value of E85).

To be complete here, I need to verify the energy content of both blends and see if the 25-30% increased fuel flow raises the fuel energy charge to more than the energy of real gas. I'm too lazy to do so right now.

But, I'm going to be cruising along well after you are stranded on the side of the road thumbing a ride with a gas can in your hand.

Respectfully, I see this as less energy per tank full of gas, don't you?

(But, your point may well be why the OP felt more "power" with E85 - good on you!)

- Jack

 

^^^^By adding more fuel into the combustion chamber, you are also adding more solid matter, therefor increasing compression.

Just a thought, to add fuel to the fire. pun intended