With only 2/3 the energy of gasoline, ethanol costs more per mile


The above was taken from this website: With only 2/3 the energy of gasoline, ethanol costs more per mile - zFacts

I thought it was common knowledge that Ethanol does not provide as much energy as the equivalent amount of gasoline. Totally irrelevant whether you are comparing Ethanol to 93 Octane or 87 as they both,93 and 87, have the same energy content.

The higher the compression ratio of an engine the more energy/efficiency you get just look at Diesel engines for a comparison.: https://forums.anandtech.com/threads...conomy.198458/

However with the higher compression ratio you have to have gasoline that will not pre-ignite before it is supposed to hence higher Octane rated fuel.

So if the car manufacturer recommends, or as with my NA Range Rover INSISTS, that you use "premium" you should as even with anti-knock technology you will damage the engine, valves, piston head, with continuous pre-ignition.

Ethanol when blended with gas/petrol has the effect of increasing the Octane rating in a "cheap" way.

As an aside people in the boating world with older engines, like me, are very concerned about the detrimental effects of Ethanol on fuel systems that were never designed to handle it.

Even more modern car engines, say 5-6 or more years old, may well not handle anything with more than 10% Ethanol such as E85.

I run a water/methanol injection system on my 2005 XJR. This allows me to use 87 Octane fuel in an engine that actually has a rather low compression ratio UNTIL the super charger kicks in. Most of the time when cruising at 1500 rpm, in top gear thats about 68 mph, the SC is not really functioning and the 87 Octane fuel is no problem. However if I kick down the SC effectively raises the compression ratio where the 87 Octane fuel would cause bad knocking/pre-ignition without the water/meth.

Also "cleaners" in gasoline were mandated a number of years ago, no matter what the Octane rating, to help counteract emissions. Its arguable whether some brands have more "cleaners" than mandated.

 

My impression, FWIW, is that the main issue boaters face with E10 is phase separation due to moist storage environments


Cheers
DD

 

Correction! I mis-spoke

The general consensus is that E10 yields about a 3% loss in fuel economy

Cheers
DD

 

That is true since E10 and E85 fuels can absorb 50 times more water from the atmosphere than non Ethanol fuel.

Thats not a problem if you burn thru your fuel relatively quickly however if you store your boat/car in the Winter..........

Fuel systems not designed to handle Ethanol can have a number of undesirable mechanical issues on top of that.

 

I have never done this however in theory its not difficult to see how much Ethanol you have in the gas you use.

Just need a small "test tube" like bottle in which you put some gas and mark where it comes to than add some water and shake well and allow to settle out.

The Ethanol should make a milky mixture and you then can estimate just what % it made up of the original gas you put in the bottle/tube.

 

So much would depend on the storage conditions/environment. And experiences seem to vary hugely.

I deal with older, stored cars all the time and have never seen/experienced phase separation with E10, personally. But, in fairness, none are ever stored outside in the weather.

E10 has been ubiquitous in my region for decades and to be perfectly honest I've never had an issue with it in any of my cars...or lawnmowers, hedge trimmers, etc.

Cheers
DD

 

I got to see it when I drained the tank on my x300. There was quite bit of water in the fuel.. The car sat outside under a tree for 2-3 years and a year at a mechanic shop before that.

 

Touch wood I have never had a problem so far.

I add stabilizer to any fuel tank that will not see use for the Winter.

 

Which brings to mind a problem that XJS owners are spared.

For years...decades....the Jag sedans (Series 1-2-3, XJ40, X300) had fuel fillers horizontally mounted at the top of the rear quarter panels. The filler neck is in a 'pocket', and the pocket has a rainwater drain. If the drain clogs (they often do!) then the pocket fills up, leaving the filler neck standing in a pool of water. If the cap seal isn't 100% perfect the water migrates right into the gas tank!

Many curse this arrangement as a design flaw. Totally false, of course. Jaguars don't have design flaws. They have "Interesting engineering features"

Cheers
DD

 

It does not matter which octane gasoline, the engine runs on both good. I always use octane 98 (RON). Ultimate of BP, the only without extra additives and ethanol here in the Netherlands. The reason is more miles per gallon and more throttle response. Clear difference at both my Jaguars with a AJ16 engine.

 

Possibly because the AJ16 uses knock sensors.

When using the lower octane is possible, perhaps likely, that some detonation is detected by the knock sensors. This results in the ignition timing being automatically (and instantly) retarded....which in turn reduces response and hurts fuel economy.

When higher octane is used there's no detonation....and ignition timing reverts to optimal settings

Cheers
DD

 

I use 87 octane and most of the year it contains 10 percent ethanol. 2002 style, runs fine, no ping or knock. I would probably get better fuel mileage with a higher octane but with the price difference my money goes further with cheaper gas. Not suggesting any one to do as I do, just letting you know what works for me.

 

If you want some extra power you can always try 2 cups of Lucas injector lubericant and 2 liters of Xylene, its similar to Toluene but has a higher natural octane rating. Should add a few numbers to make DIY race gas.

 

If your car is not tuned to take advantage of it a total waste of time.