Removing Ethanol from Gasoline

[nibs]

Right, however the alcohol takes water into solution with the fuel, which is then burned in the chamber, the water as it becomes steam adds volume, thus increasing the energy available for moving the piston. Over the years there have been many water injection systems used, some even on race car motors. Is there an optimum water content which would actually increase the mileage of 'gasohol'?

[gone-ot]

...water (but more typically water-alcohol) injection is used to control DETONATION, not produce more HP.

...true, you "boost" the HP by using super- or turbo-charging, but the water injection is there ONLY to keep the engine from "detonating" instead of "combusting."

...anybody remember the turbo'd Olds engines of the 1960's that had a separate little bottle of GM Turbo-water (H2O+ethanol)?

[Dr. Jerryrigger]

Originally Posted by Old Tele man

...water (but more typically water-alcohol) injection is used to control DETONATION, not produce more HP.

...true, you "boost" the HP by using super- or turbo-charging, but the water injection is there ONLY to keep the engine from "detonating" instead of "combusting."

...anybody remember the turbo'd Olds engines of the 1960's that had a separate little bottle of GM Turbo-water (H2O+ethanol)?

Back before intercoolers, knock sensors, and computers...
These days most people go to a mechanic to fill there windshield washer fluid, filling up turbo water is too much to ask of your customer.

[Olympiadis]

Nerys, I haven't posted here much but I like your thread and what you are doing so I wanted to jump in.

First I have to say I'd never before tried to imagine the sight of a 380 lb man in a tiny Metro pulling a small trailer. There's just something not so right about that.

I looked over your web-site as well. I suppose someone could have retarded your initial timing a bit to make up for the clogged EGR system. I like Harbor Freight, but I have to suggest you get a better quality timing light like a Craftsman dial-back style unit from Sears. In some cases it's worth going for the better quality, and IMO a timing light is one of those cases.

I don't want to come across as a know-it-all type, but I have done extensive testing myself back in the early 1990's starting in 1991. I want to say that you are definitely on the right track with your thinking.
I can't say that I like your testing methods as they are no-where near controlled enough to give reliable results, as far as testing procedures go. I do think that the trends you are seeing are in fact correct, and that you will continue to see them in the long-term barring other changes or outside forces.

In my area of Illinois back in 1991 some stations (namely the one I used) started offering the 10% Ethanol mixture, though you could still find E0 at many stations, making it very easy to run comparison testing.
I was doing both drag racing and fuel mileage testing at the time, and I first noticed problems on the drag-strip with reduced power, and need for adjusted tune. Most people did not notice the power difference because they were not tuned near the edge of maximum power. This is a big factor that hasn't been mentioned here.
My car was tuned to the lean limit at WOT and with the maximum spark-advance in each gear. This situation made any change in the fuel very noticeable and measurable. The actual density of the fuel with the E10 changed hardly at all, if any, but the energy content per mass changed, and the burn-speed in the chamber slowed down.
I wasn't happy about this at all, but I was even less happy with the effect it had on my Carter style AFB (aluminum four-barrel) carburetors that I was using on my cars at the time. The Ethanol would cause white crusty deposits and crystals to form on some surfaces of the carburetor to include the tiny air-bleed passages. Clogged air-bleeds cause serious driveability problems which was the red flag that led to the corrosion discovery. When using the E10 I had to tear down the carburetor for cleaning at least once per month. During tear down I also started noticing little pools of water in the bottom of the carburetor fuel bowls. The Ethanol was absorbing moisture from the air in the fuel tank and from the air above the carburetor fuel bowls, which are vented. Sometimes while taking off hard from a stop the water would be pulled back and cover the secondary fuel jets, which caused a sputtering for a few seconds until the water cleared the system.

While I had worked with both Ethanol and Methanol before and was fairly familiar with the effects, I had never used either for long-term street driving. Normal procedure for racers running alcohol is to either drain the system after racing, or to flush the system with gasoline - the gasoline being the best option because it cleans the alcohol away and also allows for much easier cold starting when ready to run again.

You would think, and I suppose most people do, that the small amount of Ethanol in E10 would have minimal effect in most cases of daily driving. Well, yes and no. In some vehicles it has little or no noticeable effect. It all depends on the individual set-up and the state of tune.

If the engine and/or driving conditions would favor a slower burning fuel, then one might break even or possibly profit by the results of E10. However, this would be very rare.

For example, if a racer was running a very conservative WOT tune of 12.0:1 AFR and 8* less than the maximum possible spark advance, then slowing the burn slightly is likely to go unnoticed. For a vehicle running 11.0:1 AFR, the change would probably not even be measurable with test equipment. Very rich AFRs burn so slow already that even changing the spark advance up to 10* (added) can often show no change in performance whatsoever. I have seen this in my own tests.

I also wanted to add that increasing fuel octane will also in most cases, slow the burn-speed in the chamber.

For best fuel mileage I can tell you from much experience that you do NOT want to increase your octane. Even low grade 87 octane is normally more than enough to cover the maximum load that your engine will see, even when going WOT up hills. For fuel economy style driving or hypermiling, you need nowhere near that high of an octane rating. In fact if you could find lower octane than 87, you would see improved mileage and your engine would perform better at lower RPM as well, which would skew your maximum fuel efficiency to a lower vehicle speed, as well as raise it across the board. Your only danger with low octane fuel is at certain high load levels, but is also dependent on intake air temperature and the metal temperature around the combustion chamber.

Even so, most modern engines have knock sensors that will detect spark knock and/or detonation and can adjust/retard up to 10* of spark advance (some systems can do more) to protect the engine. Failing all of that and you still have some occasional knock and you're at a relatively low throttle opening, your engine's VE is still so low that there is still very little chance of engine damage.

What I'm saying is that I don't recommend you trying to increase your octane with your washed gas. If anything your washed gas would already have reduced high-end volatiles and contain a bit of water, both of which will slow your burn down. Your testing will probably show you this eventually.
If anything I think you should try to increase the speed of your burn with your washed gasoline. There are several ways to do this, but one of the simplest is to just add a small bit of Acetone. In my experience wet-flow systems like the TBI or carburetor usually respond favorably to the Acetone, especially in cold conditions when slow burn is more of a noticeable problem. That's to say favorably in relation to burn-speed and fuel efficiency, and to exclude any side effects of the Acetone damaging rubber parts over the long-term. A warm-air intake would also have a similar effect of increasing burn speed by two mechanisms: the added heat and the better fuel vaporization and distribution. I'm just not so sure your combination would respond best with the added heat given your recent problems with EGR and spark advance. If you load your car with a lot of weight, the added heat of a WAI might cause you some knocking in the summer.

Still, I recommend you try and test different things and go where the results lead you, rather than from my advice.

My past testing had shown very consistently that, all things being equal, and with a naturally aspirated engine in good working order and in tune, the E10 will reduce fuel economy by varying degrees (percent). The differences were not directly related to the energy content difference by the way.
The factors that mattered most were things based around the changing burn-speed, like piston speed and load.

Burn-speed needs to match piston speed for an efficient transfer of energy.
In general, light cars with a lot of gear (more torque multiplication) were more lightly loaded (engine wise), and respond the most (negatively) to E10.
Heavy vehicles with highway gearing responded least (still negatively) to E10.

Also, carburetors and TBI (wet-flow systems) responded most (negatively) to the E10.
MPFI systems responded least (negatively) to the E10.

Other things that alter burn speed such as WAI and/or Acetone gave similar results but in reverse because of the increase in burn speed.
Lightly loaded vehicles with fast piston speed like fast burning mixtures.
Heavily loaded vehicles with a relatively slower piston speed like slower burning mixtures.
(don't confuse piston speed with RPM, they are not identical terms)
- and in all cases E0 produced the best results for fuel mileage.

A couple of exceptions were noted when the vehicle was not running in perfect order due to high mileage (lost compression), or misfiring cylinders due to weak ignition or faulty plugs. A car with a faulty tune (even with MPFI) would respond very negatively to the addition of E10 or anything that would slow the burn rate. Apparently the slower burn would increase the rate of misfires, and/or the alcohol would push (decrease) the misfire threshold.

Also, an engine tuned to the edge, as in the lean-limit (open-loop tune), would show a very pronounced negative effect from the E10.

I have friends who race with boosted MPFI systems (turbocharged) that run on high octane race gasoline, Methanol, Ethanol, E85, and/or gasoline mixed with Toluene or Xylene. Highly loaded turbocharged systems have high intake air temperature and naturally have a very high burn-rate when loaded, even when running very fuel-rich AFRs. They see a very significant power increase when running a fuel that will slow the burn rate and resist detonation under load. Their part-throttle and fuel mileage leave a LOT to be desired though. They experience regular spark-plug fouling and engine oil contamination when using the slow burning fuels for street driving. A highly tuned MPFI system with E85 is streetable, but still quite inefficient.

I prefer to use OLSD (open-loop speed-density) tuned engines as my concrete baseline and yardstick for testing as the results are dead-on consistent, and I don't have to fool with keeping track of closed-loop adjustments to fuel trims as the ECM tries to make up for whatever change you are testing. I test closed-loop systems as well of course, but I am more hesitant to trust their reliability without extra testing.

I have talked a lot about testing, so let me say a little about my methods.
I use multiple test loops of a 60 mile highway route for highway testing to get average of 3 loops. I also have a stop-n-go route that (I rarely use) I do ten laps/loops, and average two or three sets of ten loops. I test between 0100 and 0500 in the mornings and use a Davis weather computer to keep track of conditions. My filling method has always been to fill to a viseable spot in the fuel filler neck while sitting in the exact same spot at the same gas pump. I have found this the most reliable besides using a custom fuel-cell (tank) with a narrow filler tube (like a beaker top).
I have used various things for scanning & datalogging: Diacom, LS1scan, EFIlilve, TunerProRT, TunerCat, WinALDL, etc...
I use an Innovate wide-band O2 sensor to track AFR.
I use an older style Vericom2000 accelerometer for power testing (racing).

I've been doing this for a long time and I trust my testing methods after revising them slightly over the years to be more thorough, but I always suggest that people get their own test equipment and do their own testing.
Different cars and set-ups can and do react differently, and the more testing being done out there, the more little discoveries will be made.

Sorry for the long post.

[Funny]

That post was Epic Long...

[robertwb70]

I have to take issue with all the references to "burn speed" in there, exactly how do you measure "burn speed"??

[Olympiadis]

Originally Posted by robertwb70

I have to take issue with all the references to "burn speed" in there, exactly how do you measure "burn speed"??

Well, if you've been tuning engines for a long time you will get a feel for it.

Using test equipment you follow the burn speed in the chamber by watching a combination of things: AFR, EGT, KR (knock retard), power output, CTS (coolant temp), MAP, and several others that are more indirect, or a direct determiner of.

I'll try to give you a few examples now, and maybe more later if necessary.

The first thing to get a handle on is to understand spark advance - why you need it and how the engine reacts to it.

At certain times the burn speed in the chamber is very slow. When you first start your engine cold and you're at an idle (throttle closed), the burn is very slow. Your ECM/PCM calibrations are set to make up for both a slow and an incomplete burn in the chamber. You will see: increased spark advance, extra fuel enrichment (cranking time-out or after-start, and warm-up enrichment), and the ECM/PCM waiting to go into closed-loop mode. The spark is started sooner in the cycle which increases the dynamic compression or cylinder pressure, which creates more heat when compressed near TDC, and results in a quicker burn of the mixture. The extra fuel is to make up for poor fuel vaporization when cold.
The slow or late burn results in less fuel burning in the chamber and more fuel burning in the exhaust port. The overall effect would be a lean burn in the chamber, if not for warm-up enrichment.

Try the cold start without the extra spark advance and observe the effects of a slow burn speed.

Once the engine is warm the ECM/PCM will reduce the spark advance (SA) down to the normal level for whatever load cell you happen to be operating in. At that point try reducing your SA by 10* and observe your datalogging readout from the sensors and/or your test equipment. You will see MAP decrease, and your CTS and EGT both increase. The slow burn speed causes a condition called late burning. That is a significant amount of fuel is still trying to burn during the exhaust cycle. Late burning results in less of the fuel's energy being transferred into piston motion, and more being turned to heat either late-in or after the power stroke of the piston. More heat is rejected to the metal parts, namely the exhaust valve and exhaust port. You will see this as increased cylinder head and exhaust temperature when measured near the exhaust port.

The retarded SA produces a lower cylinder pressure and therefore less heat around TDC of the compression stroke. This lower pressure and heat results in a slower burn speed. The slower burn speed results in less engine power at the crank and more heat in the exhaust.

There is a point where a slow or late-burn will become a misfire. At that point the exhaust temp will drop sharply, as well as engine power. When you run so lean as to get into lean-misfire, you will observe this.

Test: Let your car idle with 1/8 tank 87 octane fuel for several minutes until your EGT levels out. Next add a couple of gallons of pure Ethanol to your tank and watch your EGT. Next add another 5 gallons of Ethanol to your tank and watch your EGT. By at first adding some alcohol you will cause some late burning that will show up as increased EGT. After a point of adding so much Ethanol you will probably start experiencing misfires, or burning so late that the EGT then drops sharply. Your catalytic converter would then start to heat up dramatically.

Here's another example:

Starting from stoich 14.6:1 AFR,
if you start leaning the AFR a little, in most cases the burn-speed will increase at first, giving greater efficiency. At a point, often around 15.7:1 AFR (depending on the set-up particulars), the burn speed will start to slow back down. Once you get over 16.0:1 you will notice the burn speed decreasing significantly and depending on conditions, you might start seeing some lean misfires.

The lean-limit of an engine depends on load, engine speed, and also a lot on design. A high load and low engine speed will misfire before a condition of low load and higher engine speed.
This is why an across the board leaning of the AFR is not very effective at increasing fuel mileage. At one end you will have late burning which is very inefficient, and at the other end you will have lean misfires causing severe power loss under load. The right way is to tune across the entire load range. A speed-density system using a VE table which makes this relatively easy to tune for AFR. A MAF system is also tunable, but its not as easy to cover all load conditions.

Trying to run stoich over a wide range of load conditions like the closed-loop system does is only good for maintaining a given emissions level over than range, and is not good at all for fuel efficiency.

Once you start working with it, you will see that increasing burn speed by manipulation of the AFR and SA will get you increased fuel efficiency, though not necessary the lowest emissions.

I like to tune to the edge of lean misfire with a wide spark plug gap of 0.040" to 0.045", then tighten the gaps down to 0.030" or less to add a buffer and decrease the number of misfires.

One easy way to see the dramatic effect of burn speed is to go to the drag strip. Get there with 1/8 tank of 87 octane fuel and make a couple of passes watching your power output (ET & trap speed), and also watch your EGT as measured at the exhaust port.
Next put some high octane fuel in your tank. Add 1/8 tank of CAM2 114 octane, or even 100 octane unleaded will do if you're worried about killing your O2 sensor or CAT. A large amount of added octane booster or alcohol for that matter will also do the trick. The result will be greatly reduced power and a very hot exhaust manifold. You will see slower ETs and your manifolds will probably be glowing orange due to the slow and late burn of the fuel.

I see people do this at the track all the time thinking they will run faster with the race gas with their street car's tune.

Some people also think you can make up for the slower burn by simply advancing the SA and gain better power and efficiency, but that's not true. All things equal, any time you find yourself advancing the spark to make up for a slow burn, you are giving up efficiency when compared to less advance with a faster burning fuel. The only exception is if the faster burning fuel is putting you into a knock or detonation condition, but then all things aren't equal anymore.

Give it a try.

[redline5th]

Or you could just find some ethanol free gas...

There's actually a few places that sell it here... but I haven't picked any up. I would love to.

[robertwb70]

Originally Posted by redline5th

Or you could just find some ethanol free gas...

There's actually a few places that sell it here... but I haven't picked any up. I would love to.

Only places in Florida that sell anything other than gasohol are race tracks, marinas and airports. What I've been using comes from a local marina and cost $3.66 gallon and I have to carry it 500ft in gas cans...I'm going back to the gasohol because it's just too much of a PITA and not cost effective(didn't really expect it to be, curiosity really).

Best case it looks like I get a 12% boost in FE with out the ethanol but my car is having other isssues right now so I can't be 100% sure about that number.

[dmac257]

Originally Posted by rmay635703

From a drag standpoint no, the slower you go the less drag exponentially.

Where you might see a gain is the fact that some Gasoline vehicles have their gearing sweet spot at 55mph, my Dodge gets the best fe right around 40mph, my buick around 45mph, My subaru 360 right at 50mph so it really depends.

Cheers

when you say "gearing sweet spot" are you stating a physical speed that is a "design spec" ie. something I can look up someplace or something that I would need to measure by making runs at different speeds and calculating? I don't have any way to measure mpg in real time so would be interested in knowing this "sweet spot" for my cars.

Don