It is common knowledge that our internal combustion engines only burn the vapor not the actual liquid gasoline. Have you ever wondered why then that the autos are designed to spray liquid fuel into the engine to run it
"I have been able to obtain extremely high gas mileages with the system of the present invention installed on a V-8 engine of a conventional 1971 American made automobile. In fact, mileage rates in excess of one hundred miles per gallon have been achieved with the present invention. The present invention eliminates the need for conventional fuel pumps, carburetors, and gas tanks, thereby more than offsetting whatever the components of the present invention might otherwise add to the cost of a car. The system may be constructed with readily available components and technology, and may be supplied in kit form as well as original equipment. "
"One key advancement, begun in the early 1980’s, became known as “lean burn” combustion. Lean burn combustion, using up to 100% excess air, results in significantly lower NOx emissions compared to rich burn combustion which was the prevalent and standard engine technology of the time. Lean burn combustion has the added benefit of improving energy efficiency and life cycle costs for end users. Although more complex and costly to manufacture, lean burn combustion results in engine-out NOx rates that are some 90% lower than rich burn, from 15 grams/bhp-hr to 1-2 grams/bhp-hr, along with a 5-10% fuel economy improvement and up to a 50% reduction in specific maintenance costs."
"Engines that operate at lean air-to-fuel ratios ("lean engines") offer the potential to reduce fuel consumption and, thereby, lower greenhouse gas emissions. A difficult problem to address when commercializing vehicles with lean engines is the control of oxides of nitrogen (NOx) emissions. For stoichiometric combustion, the three-way catalyst technology commonly found on gasoline-engine vehicles controls emissions of NOx as well as carbon monoxide (CO) and hydrocarbon (HC) emissions; however, the three-way function is only effective in the low-oxygen exhaust conditions associated with stoichiometric combustion. Lean combustion results in oxygen-rich exhaust where the reduction of NOx is difficult."
So it appears that Brice is correct on the nitrous oxides when lean "liquid" gasoline is used. I also found this -
"One other method of NOx reduction is to run a richer fuel mixture. By adding more fuel, the amount of air is displaced, reducing NOx. The leftover fuel is handled by the exhaust catalyst, converting the CO and HC into CO2. With a liquid fuel engine, the addition of more fuel also lowers the combustion temperature by the condensing effect. Here the fuel is evaporating and absorbing combustion heat. With a vapor fuel, the reverse if true. If the engine is running lean (over λ=1.2), the exhaust actually begins to cool down, thus reducing exhaust and combustion temperatures. Now we understand the rational of "Lean Burn"!
Here's a good image of the optimum air-fuel ratio of 1.25. The currently accepted stoichiometric (when 100% combustion of fuel happens) mixture of air to fuel is 14.7 parts air to 1 part fuel. This ratio is considered a 1.0. So leaning the vapor to 18.5 parts air to 1 part vapor will results in a 1.25 Lambda ratio and very clean burn.
In 1980 while in the service on a short leave before deployment a friend and I built an evaporative Carb and installed it on a 1968 Fire bird 400cdi testing it on the back roads in Florida. 98mpg and lots of bugs to work out, acceleration was the worst problem coming to a stop was a nerve racking experience, for anyone stuck behind us as it took a very long time to get back to speed. Good learning and definitely worth pursuing, most fuels now seem to have additives that hinder evaporation.
edible planet I notice your quote is based on a natural gas burning engine. there are a few vital differences in engine design and how the fuels burn which make lean burn work for natural gas. one of the bigger ones is much higher compression ratio's. long chain hydrocarbons like gasoline even when vaporized do not like to ignite under lean conditions and the flame front travels more slowly, you can combat this to a degree by raising compression.
of course the worlds premier lean burn technology is the diesel engine, diesels accomplish lean burn by using effective compression ratios of 30:1 and up to get all the molecules real close together
seems to me that if one wants a gaseous fuel starting with propane or CNG makes more sense than gasoline, most likely safer as well.
pleas understand I'm not trying to discourage anyone here just sharing some of the tidbits I've picked up over years of being a motor head and aware that something needs to change, at the moment I'm quite pleased with my 91 diesel jetta which gets 45-50 mpg an biodiesl going 75, I'm sure I could tweak her to get 100mpg going 35-40 but...