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Originally Posted by zpiloto
I would be interested in this too since I don't know squat about petro. Ted Why don't you get the ball rolling. All I know is that there are a bunch of hydrocarbons (500) and that the octane rating of gas before they start adding additives is around 70. A good percentage of gas 35% is aromatics including benzine and tulene(sp). I also think that there is a difference in gas performance depending on the additive package and that it could be tweeked to deliver better mileage.
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Hi, "zipiloto"! Well! a rational response....
You're right...there are literally hundreds of different compounds in gasoline! Complex stuff! How many? Not important....However, we can break this down into two (rough!) classes...that which vaporizes (the aromatics), and that which doesn't. What is which? We'll get to that, later.
I had noticed...in my earlier(fuelish?) years...gasoline would vaporize quickly! All of it! Using gasoline for washing car parts ( back off, critics! LOL!) would result in dry parts in a few minutes, and rust on ferrous / iron-based parts overnight... if a coating of oil / paint were not applied quickly.
A related observation : the slight amount of (dirty) gas left in the can would either be a sticky gell the following day, or be gone (dry) altogether!
Recent gas...in the last decade or two (3?) behaves differently. For example...pour a slight amount on a hard surface (not porous)... come back hours later...and the spot is still wet! Some part of the gas does not evaporate! How much? Hmmm.... How to find out...?
I took a page from recent bench studies I had done...plugged these "ideas" into an air compressor, regulated the output( to maintain a steady flow), rigged up a long-necked glass container...from my "neat junque" collection...to measure gasoline volumes, drew a scale...taped it to the neck, filled the container such that a "start" point was marked on the scale. Then I placed the steady-state air flow hose down into the liquid gasoline...at the same time starting a stopwatch. 15 seconds of bubbling...pull the hose out, mark the "new" level of liquid gas. "Hey! It dropped!"
Zero the stopwatch. Repeat the air tube (still flowing) insertion into the liquid gas (same depth), wait 15 sec., remove tube, measure.... New level! As low? Mark it.
Repeat the inserting / stopwatch bit. Mark the "new' level at 15 sec. of runtime.
Repeat. Repeat. Repeat...until the level of the quiet gasoline was about the same as last time...indicating no (measureable) change had occurred. End of study. The container, however, still had quite a bit of liquid left in it!
Take the graduated scale ..."start" to "end of run", with all its 15 second divisions... and plot a graph (semi-logarithmic) of gasoline volume at "start" to gasoline volume at "dry" (empty). Somewhere in the middle was the "end of run" mark.
Long story short , no graph to look at(it's stored away in my research files), gasoline was ... at the time of testing... 30ish % volatile, 70ish % non-volatile ! This was fresh 93 octane pump gas from a high-turnover dealer.
What was the non-volatile? Well, I did the only thing I knew to do(at that time & place)...see if it...gasoline?... would burn. A lit match dropped into a small metal bottle cap 1/2 full of this "residue" went out! So, I placed a wick of cloth in the little pool...lit the damp end of the wick. It slowly started burning ; got a little faster as it heated things up...and did it ever smoke! Dark, rolling clouds of smoke! The wind shifted, I caught a good whiff of ... diesel bus! What did this tell me? Right! ~70 % of a gallon of premium pump gas was diesel (or similar oils)! What is it now? Who knows! But I can tell you the gasoline of years ago evaporated to nothing more than a tan ring.
I also had a sealed, glass container of old 106 octane Union racing gas. I repeated this test with a sample of old racing gas...it all volatilized (vaporized). Every last drop! And this was years old! What does this say?
I then contacted a sorta local race engine builder...and talked him out of a quart or so of 112 octane racing gas he used for his dyno break-in runs (very fresh!)...took this gas back to the test rig...ran it through the study procedure (new graduated strip on the column), and... lo and behold! ~51 % is volatile! That means ~49 % is diesel.... Times change! I am not pointing any fingers, but you can smell this / these oils going into your gas tank!
I'll bet you didn't know your GAS engine could run on semi-diesel! This is the reason I developed my gas modifier( does it need modifying?LOL!). More bang for the buck....
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