Stupid Question

As you pointed out, compression ratio in alcohol engines can be substantially higher, and you'll see that there's many 'performance' diesels (truck and tractor pullers) who use a diesel as basis for an extreme-output alcohol-burning puller engine.

What they've done, is converted the diesel platform to spark-ignition.... taking advantage of the basic geometry, strong components, mebbie make the pistons lighter, get the RPM up, and give it as much boost, and feed as much alcohol in, as they can.

From a volume and weight perspective, diesel fuel has MUCH more available energy in a given volume or weight, than any alcohol or gasoline, but you can't just throw some other fuel in, because the autoignition PRESSURE of other fuels, will not be at the same general point as diesel, the expansion pressure, and burn velocity won't be the same... and of course, diesel injection pumps and injectors are built around the lubricity, cooling action, and spray dispersion character of diesel's viscocity... so putting something thinner in there, is like putting a gallon of acetone in your car's oil pan... thins it out beyond ability to protect the contact surfaces.

Multifuel engines (like the Hercules JXLD-relatives) were made for military/governmental contracts, and were frequently based on multi-mode blocks, as well as a Kubota engine, and a few others, where the bottom end was made for diesel, but the top end could be fitted with either a diesel or spark-ignition head.  Engines 'built' to be multi-fuel field capable would be fitted with spark-ignition, and actually burn diesel fuel using spark-ignition as if it were gasoline.  The Kerosine/Distillate/Tractor Fuel concept is same-  a heavier oil, once brought up to high enough temperature, with a warm enough combustion chamber, WILL run.  It won't be as thermally efficient, nor as clean-burning, as if it were running compression-ignition, but it'll RUN.

To determine if ti's actually worthwhile, it must be assessed under an 'economic' perspective.  "Kerosene/Distillate/Tractor Fuel" operation was economically sensible at the time it was most popular... those fuels were, at that time, extremely common, and comparatively inexpensive fuel oils used for all sorts of stoves, lamps, and heaters.  Gasoline, in comparison, was a 'byproduct' mostly limited to 'dry cleaning' clothes, and extremely volatile in comparison to the higher flashpoint Kerosenes... so starting cold engines on gasoline, then switching to kerosenes was economically viable, even though the heavier fuel's output power was less than it's much-more-volatile brother.  One of the reasons why it was cheap to do this, is because natural gas pipelines and electric utility distribution were really taking off... those lamp oils were being discarded in lieu of light-bulbs, gas stoves, and gas furnaces.  There was a high volume of light oils in the market, but a dwindling demand, so price was low, and farmers took advantage of it.

But over more time, technology continued in change, and the operating cost, safety, and convenience of gasoline motor fuel improved, while demand for Kero/distillate fell.

The OP's original thread started about cost, and in today's circumstance, there aren't any liquid fuel sources available in worthy volumes, that currently offer a significant cost advantage, in a practical use method.

    Multiple people are using reclaimed oil, drained engine, tranny, hydraulic then cutting it with gasoline for their diesels.    They claim it works great, I was curious about how the gas would affect the engines??  Havent seen anything negative on it yet.

Yes, there ARE STUPID QUESTIONS.....some questions you can just google, but SUPID IS

--what color is the BLUE OVAL on my truck ?

--why do i have to stop at RR crossing and wait for the train ?

--why do motorcycle riders ALWAYS cut me off ?

YES........... there are STUPID QUESTIONS... Then there are others you can get INFORMATION if you use YOU TUBE or GOOGLE........... OR, you can ask here to get a BETTER or ADDITIONAL Information / Opinions.