In the GEET thread, Ironglow mentioned the "Fish Carburetor". The Fish was made in limited quantities. While it did increase performance and horsepower, it did not increase gas mileage as it qas advertised to do. The Fish was a relatively conventional design unit. Any unit with larger fuel jets and a larger CFM rating could deliver more horsepower.
During the "fuel shortage" of 1973, a company marketed a simple fuel saving device. It was a replacement gasket meant to go between the carburetor and intake manifold. It had a super-fine mesh screen. The idea being to atomize the liquid fuel to a much smaller droplets. The unit actually worked. A small fuel saving did result. The downside was the vehicle would not accelerate from a stop as fast as before.
Gasoline is wet. The more it's atomized (made into smaller & smaller droplets) the more efficient the engine becomes, which translates into higher gas mileage. Early cars got relatively terrible mileage despite smaller cubic displacement engines and lower speed limits. A friend of mine has a restored Model A Ford. Despite having only a 4 cylinder engine and a top speed of 45 MPH, it gets about 12 MPG! Why? The carburetor is a very simple and very inefficient design. Couple that with a simple engine that was made in a time of casual tolerances and most of the fuel was simply dumped out of the tailpipe! But, the designers did the best they could with the metals they had and how that metal reacted with both burnt and unburnt fuel. The early gasoline was extremely volatile, gave off more fumes and ran hotter much more so then later fuel. The engineers knew by literally "dumping fuel" through the engine, it would act as a lubricant/coolant (a wet floor is slippery,right?) to help preserve the engine. Fuel was cheap then!
Early gasoline IS NOT the same as today's gasoline. In fact, the gasoline of the 1930's IS NOT the same as the early gasoline or the same as today's gasoline.
The engineers developed better & better carburetors every year. metallurgy and manufacturing procedures improved too. Fuel mileage increased as everything became more efficient. But, engines still ran on a wet mixture that dumped a lot of fuel out the tailpipe. That's why all the physicists reading don't need to pull out the graphs showing how many BTU's there are in a gallon of gas. Most of it is wasted! Also, the gas of then was a different formulation, apples to oranges as it were.
A Canadian man found that early gasoline gave off fumes. Fumes are dry. Heated gasoline, due to higher molecular movement and friction, gave off a lot of dry fumes! He reasoned that if dry gasoline fumes were mixed with air instead of a wet mix, greater fuel economy would result.
He built a heat exchanger, where exhaust was used to heat gasoline and the resulting dry fumes were drawn off and the liquid gasoline returned to the tank. Very high fuel milage resulted!
But, the oil companies weren't going for it. They changed the gasoline formulation to inhibit the fumes with lead and other additives.
Ultimately, technology mostly caught up though. Simple carburetors gave way to more efficient designs, mechanical carburetors changed to electromechanical, then to digital controlled fuel injection, Metal got better & tolerances better allowing higher engine temperatures. Super spark plugs.
And so it goes...
