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We never want to fill our fuel tank to filler nozzle shut off, as that would give us a minimal surface area from which to vaporize our fuel and our mixture could then be too lean to run our engine. However, if one wanted to build a vapor chamber and install it above top of fuel tank and filler tube, there might not be much difference when tank is overfilled. One thing we definitely want to avoid is liquid fuel in our vapor supply line. Though it is unlikely liquid fuel would reach carburetor, more it wet vapor supply line, richer mixture would be at carburetor.
I envisioned a tri Y air bubbler on fuel tank floor, to evenly distribute air in tank. The line connecting to old fuel supply line, inside tank would split into two equal length lines of same diameter from a Y or T connector. The two lines are then split into two more equal length tubes (fuel proof, of course) and porous air bubblers to make small bubbles moving through fuel. This would give us a richer mixture at fuel supply line, than a single tube with no air diffusers. I would terminate my air supply lines with those bronze fuel filters many carburetors used just ahead of needle and seat assembly at end of supply line. Short term tests I did several years ago showed that ceramic bubbler filter for fish aquariums gave very fine air bubbles and did not seriously deteriorate in gasoline. They were not very expensive.
I can only guess at supply line sizes. My guess is that filtered air supply line need be no more than a quarter inch ID. The vapor supply line probably needs to be no greater than three eighths inch ID.
These are basics of a cold vapor, fast burn fuel system. I would expect improvements to come rapidly following road testing. When we know typical optimum spark timing and air/fuel mixtures, we can apply this knowledge to small engines with fixed spark timing, like lawn mowers, snow blowers and electrical power generators.
My expectations of fast burn performance is between two and three horsepower per cubic inch displacement, which would make fast burn conversion best power bang for dollar. No other modification can come close in dollar costs. Under most racing rules, fast burn would be legal for allowed fuel and add more power than supercharging or nitrous oxide injection. Yet, these power boosters will add a lot more power to a fast burn engine than to a slow burn engine. Hence, fast burn conversion will out perform slow burn by a wide margin, regardless of class allowed modifications. The fast burn conversion can also be camouflaged to look stock by plumbing supply line through a non functional fuel pump.
As to economy, Charles Pogue exceeded 200 MPG with his hot vapor, ‘37 V-8 Ford, which would rarely yield 20 MPG in slow burn configuration. Uniform cold vapor might have allowed him to achieve 300 MPG economy he was shooting for, while more than doubling stock power output. When fast burn conversions become common, performance and economy contests will lead to rapid improvements in very simple technology.
As to emissions, if we are consuming less than 10% of fuel per mile driven, emissions will be less than 10% of slow burn equivalent. Burning 100% of fuel on a shortened power stroke, will further dramatically reduce emissions, probably to less than 5% of slow burn engines. In addition, much higher power outputs of fast burn engines allows engine downsizing. A 300 cu. in. slow burn engine can be replaced with a 140 cu. in. fast burn engine and still provide a power increase. Economy is improved, along with emissions. Big cars and trucks Americans favor, in fast burn configuration will easily exceed hybrid electric cars in economy and reduced emissions, as well as power. On other hand, a fast burn hybrid could top 400 MPG if we want to go that far.
I would love to hear from any individuals or groups already doing fast burn conversions and learn what they have learned. While piston engine has had a bad rap for efficiency due to liquid fuel systems, Tesla Turbine, seldom used as a combustion engine, can be built as a very lightweight, compact, multi stage, supercharged, exhaust scavenged 30 horsepower per pound, fast burn engine. The Tesla Turbine with only one moving part is cheap and easy to manufacture in a small machine shop. The turbine requires no drive train except connection to drive wheels. No gear reductions, instant tire spinning torque and instant rotational reversal for engine braking. Stay tuned for more on potential of this remarkable engine, developed early in 20th Century and virtually ignored by industry ever since, except for vastly superior pumps.
Freelance writer published on many websites and newspapers. justanotherview.com edhowes@hotmail.com