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ever_green · 06-24-2015, 11:15 AM

this is one of the best articles i read in regards to relations of AFR and power/BSFC.

Engine Management

Basically best economy is stated to be achieved at 0.625 FAR. that's roughly 16:1 AFR. Best BSFC is achieved at 86 lbs/hr of fuel flow which for this engine is roughly about 15.6:1 AFR. The best thing about these measurements are that it's under vacuum (not full throttle) and at a nominal 2500 RPM. This confirms my experience with higher fuel consumption when I lean the mixture past 16:1 AFR despite running more ignition timing. I found 15.5:1 AFR with some EGR is best for my engine to achieve 39 mpg highway (good for a 2.5L 3300lbs 4WD vehicle).

06-24-2015, 11:15 AM	#281 (permalink)
ever_green Master EcoModder Join Date: May 2011 Location: Toronto Posts: 264 gueff - '19 Mercedes Benz A250 4MATIC AMG 90 day: 30.55 mpg (US) Thanks: 8 Thanked 79 Times in 33 Posts	this is one of the best articles i read in regards to relations of AFR and power/BSFC. Engine Management Basically best economy is stated to be achieved at 0.625 FAR. that's roughly 16:1 AFR. Best BSFC is achieved at 86 lbs/hr of fuel flow which for this engine is roughly about 15.6:1 AFR. The best thing about these measurements are that it's under vacuum (not full throttle) and at a nominal 2500 RPM. This confirms my experience with higher fuel consumption when I lean the mixture past 16:1 AFR despite running more ignition timing. I found 15.5:1 AFR with some EGR is best for my engine to achieve 39 mpg highway (good for a 2.5L 3300lbs 4WD vehicle).