Quote:
Originally Posted by E4ODnut
I did some research on "lean burn". It looks to me like a true lean burn engine is designed to run on much leaner fuel mixtures throughout the complete power band and that a major stumbling block to these designs is that of maintaining emissions standards.
Having said that, and emissions concerns aside, I see no reason why conventional gasoline engines can't get improved BSFC at lower engine loads by leaning the mix, adjusting spark timing to suit this leaner mix, and opening the throttle somewhat to maintain the required power. The larger throttle opening will reduce pumping losses or what ever you want to call it, as well as improve the thermal loss. The exact cause of the improvement doesn't really matter, what matters is that the end result should be better low load BSFC.
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I see you have a megasquirt. For sure you can do this yourself.
Keep in mind there is a band you do NOT want to run at. If you go a touch leaner then stoich, the engine will get HOT. But if you go leaner yet, the combustion chamber will start to cool off until it gets sooooo cool it won't fire.
Look for TPS openings in the 10 to 20 percent max range. Consider buying an EGT and learning what your engine is like normal. 1200 is considered on the higher end of things for most NA engines. 1500 is already blown up.
consider running more spark advance then you would expect.
consider running EGR valve open during this - it can actually cool the chamber.
and stay away from knock.