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bwilson4web · 07-19-2009, 10:10 AM

Hi,

I downloaded the spreadsheet but am confused by the source of 'fuel consumption.' I didn't see a fuel consumption input. Did I miss something?

It looks like the "contour #" defines which curve is drawn. But the logic that applies a value of "0, 1, 2, ... n" to a data point isn't clear. Is this data in the worksheets or was it copied from other BSFC charts?

The reason I ask is another model based upon drag and fixed engine efficiency and overhead gives the following fuel consumption vs speed:

I've long suspected engine efficiency, the BSFC variance, is responsible for the outliers in the data measurements. Field measurements of BSFC supports this hypothesis.

What I noticed is the "Toyota" tab shows the 1.6L engine BSFC rpm limits. Actually the limits for the 2001-03 Prius with a maximum 4,500 rpm. But field data suggests the actual BSFC is different than the published BSFC chart. There is something called the "operating line" that defines the targeted operational region for the engine.

Understand, I appreciate the effort and like the contour plots. You've given me some ideas that may allow me to combine the field BSFC data and drag function into a more accurate plot of expected MPG vs speed.

GOOD JOB!
Bob Wilson

07-19-2009, 10:10 AM	#2 (permalink)
bwilson4web Engineering first Join Date: Mar 2009 Location: Huntsville, AL Posts: 843 17 i3-REx - '14 BMW i3-REx Last 3: 45.67 mpg (US) Blue Bob's - '19 Tesla Std Rng Plus Thanks: 94 Thanked 246 Times in 157 Posts	Hi, I downloaded the spreadsheet but am confused by the source of 'fuel consumption.' I didn't see a fuel consumption input. Did I miss something? It looks like the "contour #" defines which curve is drawn. But the logic that applies a value of "0, 1, 2, ... n" to a data point isn't clear. Is this data in the worksheets or was it copied from other BSFC charts? The reason I ask is another model based upon drag and fixed engine efficiency and overhead gives the following fuel consumption vs speed: I've long suspected engine efficiency, the BSFC variance, is responsible for the outliers in the data measurements. Field measurements of BSFC supports this hypothesis. What I noticed is the "Toyota" tab shows the 1.6L engine BSFC rpm limits. Actually the limits for the 2001-03 Prius with a maximum 4,500 rpm. But field data suggests the actual BSFC is different than the published BSFC chart. There is something called the "operating line" that defines the targeted operational region for the engine. Understand, I appreciate the effort and like the contour plots. You've given me some ideas that may allow me to combine the field BSFC data and drag function into a more accurate plot of expected MPG vs speed. GOOD JOB! Bob Wilson __________________ 2019 Tesla Model 3 Std. Range Plus - 215 mi EV 2017 BMW i3-REx - 106 mi EV, 88 mi mid-grade Retired engineer, Huntsville, AL