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E85

Slip Kid

Slip Kid

That'll buff right out
Location
A cornfield in IL
So I read it's technically illegal to convert a vehicle to run on this 85% ethanol stuff. So anyways, how would one go about doing this? Stainless tanks and lines? what happens if one's "conversion" is simply filling up with the stuff? will it not run right or will it explode? it's 105 octane, I'd say that's probably more of an issue than the corrosiveness???

I dunno it just seems interesting to run a car on denatured whiskey...
 
BruteXJ said:
How about 100LL AvGas (100 Octane Low-Lead Aviation Gasoline)? I've gotten conflicting reports on what it would do to/for my engine.
Click to expand...


My buddy from college worked at a local airport as a fuel boy. In his 5.2 l zj the engine ran on it, not well but for free when you're poor, it got the job done. The exhaust did smell like ti was running on racing fuel, however the performance was not a match for the smell. And a few weeks after beginning this test, it developed a horrible rod knock. but at 160k that could have been coincidental but there's my experience with 100 low lead in an automotive application.
 
My 66 Bug loved 112LL - I ran about two gallons through quarterly to clear the lines (better detergents in avgas.)

Increasing octane, however, will actually DECREASE performance unless it is done to complement a high-compression engine build. The XJ will typically run worse on high-octane fuel.

Octane rating is a measure of resistance to ignition - meaning it's harder to light, and therefore less susceptible to detonation. As a result, less fuel tends to be burned in our engines when we go up past87 octane or so (8.8:1 Static Compression Ratio, Dynamic Compression Ratio much lower - I'd have to look it up.)

Conversion to E85 is also going to be more than "fill 'er up!" since the stiochiometric ratio and energy content of the fuel is different. Alcohols tend to have high basic octane ratings than gasolines, but also require more fuel for effective combustion. It's part of my research for the "Fuels" chapter of my engine book - what would have to be done to convert for fuelling with propane/LPG/NatGas/Ethanol/Methanol/Nitro/? - it's a lot of work. I never really realised how much there was to fuels - when I was playing with exotic fuels, it was on SBChevvy/BBChevvy engines that had the parts available and all the baseline work done for you. Now that I've got to figure it out on my own, it's a learning experience...

Is such a conversion illegal? Probably in CA - but not under Federal regulations. That would bear looking into - and is another line of research that I've yet to pursue.

5-90
 
it's about $.40 cheaper per gallon here, only reason I'm interested

as I said the octane is a problem.
 
Not just the octane - metering is also an issue. A gasoline fuel injection system is not capable of properly metering E85 (actually, any blend with more than about 15% alcohol) without reprogramming of the ECU and a sensor to determing what fuel is used and in what blend (many FFV - Flexible Fuel Vehicles - have an in-tank sensor that allows them to determine the makeup of the fuel in the tank by proportion, respond to concentration changes, and intelligently change the fuel metering in order to achieve stiochiometry. Feel like designing, building, programming, and tuning a new ECU?)

As long as metering isn't going to happen, neither is smooth, efficient operation.

I'd like to experiment with a few things - I think it would be worthwhile. I'm sure some GM FFV systems can be found - that saves the design phase and the initial programming, and GM ECU's tend to be easier to reprogram or recurve than Ford's - that's why GM control systems find their way into so many swaps. Kinda like the early difference between IBM PC's and Apple computers - going to the "open" architecture allowed IBM to give Apple a thorough clobbering in the market - and they're still recovering (note that the PowerPC/PowerMac finally adopted the PCI bus, and they've probably finally caught on with AGP as well. I also find it telling that Apple offered Intel's USB before their own FireWire/IEEE-1384...)

I'm not saying that this can't be done - not in any way. I'm just trying to make sure you understand that this is not likely to be simple - it's a lot of work, and what's the return? For instance, alcohols have a richer stoichiometric ratio than gasoline (usually down around 7-9:1 vice 14.7:1 for gasoline,) and that offsets the reduced cost of fuel - you have to burn more of it to do the same work that gasoline does. Also, I think (but I'd have to check...) that Ethanol and Methanol (E- and M-blends) both have a lower energy content (BTU/pound) than gasolines, and that affects efficiency AND power output!

If you'd like to get into this, please keep us posted. Have a second XJ (or something...) to drive while you're tuning your alcohol vehicle - you're likely to need it. Don't expect this to be easy...

5-90
 
once i accidently filled up on e85 and did not experience any thing different except that i was burning more fuel would never do it again tho cuz when my tank got low it was hard to start it
 
"Stoichiometric" (also, stoichiometry - refers to the "balance" of chemical reactions.

A stoichiometric reaction (often abbreviated "stoich") is one in which all reactants are consumed and produce the results.

Stoichiometry is typically applied most in fuel/air reactions. A stoichiometric fuel/air ratio (with whatever fuel - oxidised or not) is one in which there will theoretically remain no uncombusted fuel nor uncombined oxygen in the exhaust.

True stoichiometry is difficult to achieve in internal combustion engines, simply because the combustion process is started and stopped every few milliseconds. Combustion is therefore completed somewhere in the exhaust stream - usually within a catalytic converter (a device using a heated catalyst to enable a specific chemical reaction. Gasoline-fuelled vehicles typically use a blend of palladium and rhodium coated onto a ceramic matrix. Note that a catalyst is not itself used in a chemical reaction - it simply enables one to take place, or to take place more fully.)

Determining an effective stoichiometric ratio for an engine fuel is essentially a matter of determining how much oxygen would be required to totally combust a given sample of fuel, then determining how much atmospheric air will supply that amount of oxygen. For instance, an average of 14.7 "weights" (we'll use grammes) of atmospheric air are required to provide enough oxygen to combust a single gramme of gasoline - therefore, the stoichiometric ratio (theoretical) for gasoline is 14.7:1.

Stoichiometric ratios, by convention, list the amount of air needed for a given amount of fuel. In many cases, the element ":1" is dropped and understood.

Alcohols are able to run much "richer" (less air) due to the fact that oxygen is constrained as a part of the alcohol molecule. Fuels with greater oxygen content require less air to combust, until we get into self-oxidising fuels (like white phosphorous and nitroglycerine, which are perfectly capable of conbustion under water or in a hard vacuum.) Stoichiometric ratios are not given for fully-self-oxidising fuels, as atmospheric air is not necessary and therefore cannot be quantified as part of the reaction. Other self-oxidising fuels include "black" gunpowder and nitrocelulose (guncotton.)

Fuels with a "nitrate" group as part of their makeup (-NO3) are able to run even richer, due to the increased oxygen content. Nitromethane, for instance, runs in a stoichiometric state down around 2:1 AFR.

Various additives, in significant quantities, can affect the stoichiometric ratio of a given fuel by increasing or decreasing available oxygen and decreasing or increasing the requirement of atmospheric oxygen supply.

Hydrocarbon fuels typically do not contain significant amounts of oxygen, and therefore run much "leaner" than alcohol fuels and similar.

Feel free to ask if you have any more questions, but I'm hoping I did a decent job of simplifying a complex chemical concept... If you still want to Google it, go ahead - but it's spelled "Stoichiometric" (whether or not I got it right earlier - I just checked.)

5-90
 
Doesn't Av-Gas also have an anti-freeze in it? I used to run it in my jet-ski, but then I switched to Union 76 108 race gas. MUCHO GRANDE better!
 
It would make sense, but I haven't checked AvGas additives lately. Still, considering temperature drops at altitude, it would be a good idea.

Part of the reason for such high octane in AvGas is that the engines are designed with high sea-level compression, so it can make up for paucity of air at altitude. Kinda the same reason there are so many turbo Diesels out there - otherwise, they'd have to derate the engine to keep particulates down at altitude. Adding the turbocharger allows them to burn more fuel (to make useful power) at altitude - I'd be willing to be nearly every Diesel in Denver has a turbo on it... Quite a few GA engines are also turbocharged - especially if they have a ceiling above 10,000'

5-90
 
5-90, your explanation was both clearer and more thorough than I found on Google. As far as the spelling, I think I saw it three different ways in the thread, so I just picked one.

To pick your brain again:
I would assume then, by your explanation, that since I'm driving a stock 4.0 using a more "open" air filter (and muffler), and never exceed an elevation of 4,000 feet or so, I would be best off running the lowest octane(87) available?

Thanks,
Kevin.
 
You should run the lowest octane that does not ping!

Two reasons -
1) There is no sense in paying for something from which you will not benefit.
2) Running a higher octane that you actually need will cause you to lose performance, not gain.

Consider that I've driven stocker RENIX across the country and pack (loaded, unloaded, towing, not towing, and ALWAYS through the mountains!) and have always run it on the cheapest gas I can, and I've never pinged enough to be a problem. I will not go so far as to say there was no pinging due to fuel - but the knock sensor and timing adjustments programmed into the RENIX ECM have always proven equal to the task, and I've not noticed any loss of power (the problem when timing is retarded.)

So, I'd go so far as to say that 85 octane is fine - if you can find it. 87 is plenty.

Sounds like you've absorbed what I had to say rather well - good job. I spend an awful lot of time trying to take complex engineering, chemical, electric, and other technical concepts and distilling them so that someone without a technical education can understand them - with the intent always being making information more accessible. There is no such thing as useless information - you just haven't figured out what to do with it yet (I'm constantly amazed how some real-world thing I've learned 20 years or so ago comes back to save my bacon much later...)

Anyhow - 85-86-87 octane has done me find from Half Moon Bay (elevation, about zero) to the Salton Sea (elevation, somewhat below sea level) to the Rockies and Denver (elevation - at least a mile.) Keep the control system and tune, and you can pretty much forget about your fuel - you'll run on anything with the RENIX controls...

5-90
 
You bet - the 1991MY showed the intro of ChryCo electronics and their brain-dead SBEC unit (which I never really did care for...) and wonderful things like running the regulator for the alternator through the SBEC, adding the PDC underhood, and some other stuff I'd design out of a resto.

Both the EGR and knock sensor disappeared for 1991 - while I don't regret the loss of the EGR, I like the adaptability gained from the use of a well-calibrated knock compensation setup. Given a choice, I'll stick with the RENIX setup - mainly because I think it can adapt to more and it's not as picky as OBD. It also keeps most of the critical modules out from underhood - the one that's under there is the ignition, and it's divorced and opposite the exhaust - I haven't broken one yet. I've only heard of two failed RENIX ECU's - both lost injector drivers (which are MOSFET transistors, or similar - and should be replaceable if one can find the replacement parts and can handle a soldering iron.)

I'd not mind getting data on ethanol conversions - but doing it with fuel injection, rather than carburettion. It's easy enough to do with a carburettor - usually, just a matter of changing jets and playing with the ignition timing curve. As long as your compression is high enough (DCR ~8:1, as I recall) you can make it work.

However, how much work is needed to make it work with TBI? MPI? That's the part I need to play around with - and I'm looking into ways to make a dyno to load an engine that I want to have going on a run stand for testing...

5-90
 
Brazil uses almost exclusively alcohol fuels. It does not atomize as well as gas at lower temps and they actually have a small propane canister on some models, canisters like you use for a propane torch. It is used just to help start, especially at lower temps.
 
I don't know the exact numbers, but alcohol of ANY kind has less energy density than gasoline (BTUs [heat/energy]/unit weight). Methanol is used in race applications because it's able to be compressed to hell without pinging, and also provides a great deal of internal cooling due to its low specific heat (it evaporates easily - whatever material is providing the heat for evaporation is cooled).

The only advantage to high-test, as stated, is if the motor's tuned for it. High compression motors do have the advantage of higher thermal efficiencies, but not enough to make it economically feasible. Even motors tuned for E85 see something like a 30-40% reduction in mileage (manufacturer's numbers, not mine, as printed sometime earlier this year in The Wall Street Journal, in an article about E85/gasoline blends). The E85 industry claims a far smaller loss of 5% I think it was, again per that article, but this is very inaccurate.

I'm imagine, 5-90, that all that's needed for a TBI adaptation is to change the jet size as well, for as I understand it (which may be ass wrong), TBI is basically computer-controlled carburation. I dunno in an FPR would work, but so long as the computer expects the fuel pressure to be x psi @ y volts, if you are able to increase the pressure, and therefore the volume, at the same voltage (maybe only easier said than done - this is where lack of on-hands experience really pisses me off cuz I don't know if my ideas are good or bad!), you should be able to compensate for the increased fuel requirement.
 
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