Backcountry Pilot • Autofuel VS avgas

Autofuel VS avgas

Nothing happens without it. Discuss fuel locations, quality, alternatives, and anything else related to this critical resource.
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Re: Autofuel VS avgas

Oldcrowe wrote: 100% autofuel it made my balls swell up and stick... sight gauge(s) that is


That's a really good line, but before everyone else's balls swell up over the turn in topic I am going to put this article in here. Equipment, and its limits, (including that used to make balls) is everything when it comes to getting mileage from ethanol/methanol. I have thrown methanol in because it has about the same energy as ethanol and draws in those who favor the coal to methanol concept over ethanol but is still a wayward child to oil and should draw the same fire. Check out the results.

http://www.nationalreview.com/articles/ ... ubrin?pg=1
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Re: Autofuel VS avgas

180Marty wrote:
A Prius will not benefit from a cocktail of gas/ethanol that is 2 - 2.5 points higher, so why even argue that fact.

180 Marty wrote " So octane doesn't figure into it? Can you explain why my friends 2007 Toyota Camry gets 29.5 mpg on E30, 31 mpg on E10, and the official rating for highway is 30 on straight gas I assume. I drove him to a doctor's appointment a few days ago and it really drove nice. I tried to feather the throttle but kept snapping our necks----he said since the gas pedal recall it does that """. :D

Seeing how your friend probably lives in Iowa too and has been drinking from the ADM well that spews the BS that Ethanol is great and gas in inferior then I would expect that both of you would see better mileage by using alcohol laced gas.... In an industry that would KILL and spend millions to spout "their" vehicle gets better mileage on E-30 then on straight gas why don't they use that fact in all their advertising ????
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Re: Autofuel VS avgas

I am certainly no expert in the E10 debate.

I have said it before and I repeat myself. All the gas vehicles I have do worse on E10 and I switch back and forth. If I am to lazy I'll use my airplane tank in the truck and fill the Jeep YJ, Denali, Neon, F150, Motorcycles, Quads, Sleds. They all react different to E10. The 91 Jeep with the 4 banger is the most noticeable.

My buddy has a 2010 BMW motorcycle. The owners manual says it puts out like 85HP on regular and 115 HP on premium. It will do a power wheelie in 2nd gear on regular and 3rd gear on premium.

My point being, new vehicles have computers that change the way the engines are tuned depending on variable input from multiple sensors. This causes an increase or decrease in HP.

So the Prius IMO could get better mileage on E 10 because the higher octane lets the computer tune the engine for more HP. If the driver keeps the acceleration and cruise speed the same I guess better mileage is possible.

We have heard a parallel discussion on airplanes that run LOP and the experimental guys putting full electronic ignition and electronic fuel injection on. The changes are dramatic.

Hell I would run E100 if it cost $2.00 a gallon and the engineers make it safe for my internal combustion engine.

Good day
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Re: Autofuel VS avgas

Took off yesterday did a left downwind departure sometimes it would climb 1500' pm at 95mph and sometimes it would climb at 1200' pm :?: I'm running a 2 parts 92 oct mogas w/10% eth & 1 part 100LL 8) I think when it's climbing 1500' pm it must be sucking up the 100LL and when it's only climbing 1200' pm it must be sucking the 92 oct :?:

Also last time I checked my mogas with my tester I only got 8% eth instead of 10% I'm feeling cheated :D Must have been a malfunction at the loading rack where the big truck got the gas [-X After making my mix I showed 4% eth.

You guys need to push the hangar doors open and leave the Prius' on the ground, go make CO :D
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Re: Autofuel VS avgas

That's a really good line, but before everyone else's balls swell up over the turn in topic I am going to put this article in here.

Good read.
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Re: Autofuel VS avgas

I'm running a 2 parts 92 oct mogas w/10% eth & 1 part 100LL 8) I think when it's climbing 1500' pm it must be sucking up the 100LL and when it's only climbing 1200' pm it must be sucking the 92 oct :?:

You'll have to see if you can patent that selective separation. :D
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Re: Autofuel VS avgas

Sorry I'm contributing to this thread drift but...

Rob, your friends BMW's computer is probably changing the timing and possibly valve timing so it can use both octanes. It could be changing compression by changing combustion chamber size but I am not sure how you would do that unless it pushes something into the combustion chamber. That would reduce the size and up the compression. If you compress any fuel to higher pressure it will have more power and be more efficient. That's why diesels work so well.

I also have seen modules that you put between your injectors and the wiring harness to change the fuel distribution so you can run E85. It takes data from the exhaust and injects more E85 to correct the lean mixture. Somehow that prevents knock but your running more fuel to do it. You can retard timing too but both ways cause you to lose power and mileage. You just need to figure where the break even point is to see if it actually saves you money.

According to this guy you can run E85 in your car. I am going to put some in this old CNG truck and see what happens. It has 300K and isn't worth much anyway. I was thinking of running half and half and see what happens.

http://www.youtube.com/watch?v=WEZuVfAAK_I


Marty, why do you compare "Actual" E30 and E10 figures with "Published" E0 figures for the Prius. Go fill up the car with real gas and drive the same course. Then we might believe you, but I doubt it because it's obvious that your biased on this subject. No car I own gets better mileage on E10. My trucks drop 30% and I have a 2000 Mercedes and it drops 10%. Both have less power using it. That's real word testing. It costs the same so why should I use it?
Last edited by Jaerl on Mon Dec 05, 2011 9:47 am, edited 3 times in total.
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Re: Autofuel VS avgas

180Marty wrote:
I'm running a 2 parts 92 oct mogas w/10% eth & 1 part 100LL 8) I think when it's climbing 1500' pm it must be sucking up the 100LL and when it's only climbing 1200' pm it must be sucking the 92 oct :?:

You'll have to see if you can patent that selective separation. :D


I rock the wing to keep it mixed :lol:
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Re: Autofuel VS avgas

I think some folks are mistaking octane rating for energy content. They are unrelated.

Nonetheless, an engine control on your car can change the ignition advance up to just prior to the onset of preignition, which allows greater efficiency (more of the charge gets burned more completely, rather than being expelled out the tailpipe). The octane rating plays an important part in determining just how far the timing can be advanced.

Airplane engines simply don't do this. The addition of alcohol reduces the energy of every charge going into the cylinder because alcohol has considerably less energy than any fraction in the gasoline blend. In addition, the enthalpy absorbed when alcohol is vaporized is greater than for the petro fractions and further reduces the efficiency of the engine. This is also the reason why carb ice is more of an issue with E fuels- the venturi gets colder.

A car engine can adjust mixture and timing to compensate. Aircraft engines only allow adjustment of mixture. Pure ethanol engines are designed to take advantage of the large octane rating with large compression ratios and ignition timing advances to more than overcome the enthalpy and energy density losses; blending with gasoline fractions largely prevents these techniques from being used.

Nothing prevents the energy density of mogas from being higher than for avgas in some cases. But the ignition advances in most of our normally aspirated Lyc's and TCM's are specified with 80/87 in mind.

I got equivalent performance with E0 mogas except when using a single specific brand, and I attribute this to the fact that the blends had different energy densities. All I'm saying is there may be more variation in mogas. On the other hand. I also had at least one case where my RPM on climbout absolutely exceeded redline (fixed pitch), something that could NEVER have happened unless something were different with the fuel.

As for using alcohol in your aero engines, I know some RV pilots who have had trouble with their tight cowls running mogas at high altitude with alcohol (pressure oscillations in their injection rails due to vapor). They had to jump through some hoops to make it work more reliably.

If you claim to get better performance on mogas, great. If you use it with bladders, great. But if you use E gas with bladders, I have personally seen a new set of bladders go south after only a couple years, and the guy was a 10% ethanol user (against his STC, but whatever). They were expensive, and he lost out on a good portion of summer flying to replace them both. The inside surfaces of the bladders were actually crackled all over upon pulling them out of the wings- much worse than even really old bladders that are beginning to leak look like when removed.
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Re: Autofuel VS avgas

Ethos, is some pretty interesting stuff for a fuel additive. I used it when fuel first went to $4.00/gallon and I actually think it works. It was developed to reduce emissions by making the fuel burn more completely. I never spent a lot of time testing it but I used it in my Mercedes and got results that really surprised me. I have always wondered how it would work in a plane.

I didn't test it for a long time and Fuel pump differences could have something to do with it. I got over 40 MPG out of a 2000 Mercedes SUV with a V6 twice. To do it I was driving on flat roads, 62 mph with the windows up, no AC and the mirrors were in. 6 Cyl 3.2 gas engine with 12 spark plugs. The Mercedes has a fuel flow gauge and it shows 62 mpg is the best mileage for the car. The gauge showed about 32 mpg but when I filled it up, my mileage was actually over 40 and the car has oversized tires.

It seems to work best if you put it in your tank and let it sit for a week or so. Don't exactly know why. I think it is supposed to change the fuel at a molecular level and I guess that takes time. I don't know the exact mileage around town but I was getting around 50 miles more per tank while I used it. It is expensive so I don't know how much you really save. I have never really put it on paper but I do know it helps your mileage. Didn't seem to work as well in a Chev Truck. Anyway, here's a link:

http://www.theethoschallenge.com/about-ethosfr.php
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