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REAL lean burn? anything leaner than a factory "optimized" 14.7-1 is lean burn... The reason lean burns not all the rage.. EPA, and $.. Lean burn does create more NOx emissions, which can be curbed but with a MUCH more expensive catalytic converter. the 3 way cats in use today NEED 14.7-1 so they have the right mix of chemicals to get rid of polluntants and not get plugged up.
Hondas solution to a homogonous mixture was to use swirl ports on the vtec-e motors, all new heads since 96 use similar swirl ports because the mixing of the fuel and air to estabilsh the "lean burn" also promote better emissions at richer air fuel ratios.
Anyways been doing some more testing, although colder winter weather, snow tires, winter gas, all have a pretty detrimental effect on mpg, car still does a pretty regular 32-36mpg better than epa average of 28 and thats about 80% city/back county driving.. and I don't really hypermile, i still drive like an idiot.. i know if i slowed down i'd get better fuel milage but ??
I have found out that there is a limit to how lean you can go.. not so much as it missing, or maybe it is and its just to hard to tell, but it doesn't seem to do as well if i lean it WAY out(past 20-1) and have to apply more throttle, than if i leave it slightly richer.
The other thing is that at around a 20-1 af at a 55mph cruise, since the temp is below 30 outside, simply turning on the heater causes the coolant temp to plummet, I really think the thermostat isn't even opening on the highway the motors running cool enough to not have too. The egts at 20-1 are lucky to be over 1050, at 14.7 its over 1300. I also have the start up tables leaned out too, but it still has to be slightly richer when the motors dead cold to get it to warm up. I need to go a grill block, but like i said its been below 30 and i'm not that hardcore..
For those still reading i'm gonna put some of my warm up air fuels and what not just for reference..
Start up dead cold from 25* or so it idles around a 14.7-1
Slowly leans out to about 18-1 at idle when warm
Crusing at part throttle low load is 18-1
Cruising at 70-75 it dips down around 14.7-1
Full throttle drops to 13.6-14 for peak power
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