Quote:
Originally Posted by racprops
That was one of the ideas I was considering.
Which is why the question on the PCM.
It is a stated fact by many automotive reports that the PCM has been programed to run dirty, to use more fuel than need just to keep the cat lit/hot.
There was (and I cannot put my hands on it, I have been researching these ideas for more that 10 years) a article/report supposedly written by the very man that invented the Chevy Tuned Port Intakes that originally it gave 45+ MPG and burned so clean there was no need for a CAT.
BUT as cats were mandatory and such great MPG was outlawed he was forced to detune it.
But that maybe why the Easter Egg "Lean Burn Cruse" was left in the PCM for those early cars.
There are so many such reports out there...
Rich
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Manufacturers do not create a dirty engine just to clean it up with the catalytic converter (CAT). A modern three-way CAT needs a fuel mix right around lambda to be effective. This is because it must remove not just HC and CO but also NOx. When you run an engine lean, the CAT becomes ineffective. The older "clean" engines of the past ignored the non-controlled NOx output. I owned Chrysler's with lean burn engines, Honda's and Mitsubishi's with MCA Jet engines. For the time and technology, they achieved excellent fuel economy.
There is a fellow on here who is modding the engine of an Eagle Talon (Mitsubishi based engine) and getting tremendous results as well as relatively low NOx. This is due to the fact he is implementing many of the same methodologies of the fabled Smokey Engine - high enthalpy lean burn. He is up over 30:1 air/fuel ratio using a turbo and EGR. I have achieved 28:1 fuel ratio with a 3 cylinder normally aspirated Daihatsu gasoline engine using HHO as my source of hydrogen for augmentation.
In 1980, Tel Aviv University published a paper on learn burn flame fronts and the ability to initiate and continue combustion of up to 100:1 fuel/air ratio (methane fuel) with hydrogen augmentation and the addition of sufficient heat and turbulence. The Talon Owner is on the right track. If he can keep the flame front below 2300 degrees Kelvin, very little NOx will be produced. Now, all you must do is produce useful power.