Can I plot a BSFC map w/SG performance mode?

[SentraSE-R]

I upgraded my v3.17 SG-II to v4.06 under the Ecomodder Group Buy in order to get performance tracking data recording. Standard data parameters tracked are distance, speed, and time, but you can add one more parameter such as gallons/hour or mpg.

I have set my measurement units to metric for testing, and will use liters/100 km (LHK), which logically makes much more sense than extrapolating or differentiating fuel consumption from GPH or MPG.

The testing I plan to do is to record a series of 18-30 mph and 25-40 mph (OK, 28-47 kph and 39-63 kph) pulses at different LODs to do a poor man's BSFC map. Does anyone know if this will work? Has anyone tried the SG's performance data logging? Should I try doing this outside the 1500-2500 rpm range to hunt for the BSFC sweet spot?

I ran one freeway acceleration performance data logging run with US measurement units today in my wife's car. It only recorded data for 11.83 seconds, even though Linear logic says it can record up to 24 seconds. And it didn't record my GPH parameter. Apparently I didn't turn monitoring on before arming the SG for the run.

Your suggestions and criticisms are appreciated, in advance.

[jakobnev]

I think accurate torque measurements without a dyno will be the most difficult part.

Using just M, Crr, and CdA, and measuring the rate of rpm increase will get you a number, but i think you'll have too many sources of error.

Once you have torque, rpm and fuel flow rate drawing the map will be easy.

How many data points per second does the SG log?

[SentraSE-R]

Unfortunately, torque isn't an OBD-II measurement parameter, and horsepower measurements are very inaccurate. The sampling rate is every 0.2 sec without the user-designated parameter monitored, and every 0.4 sec with the user-designated parameter monitored.

[SentraSE-R]

Back to the drawing board. I'll need to daisy chain my UG to my SG to see LOD. The SG in Performance Mode shows distance, speed, and time. It leaves no way to display LOD.

When you save a performance run, it only saves distance, speed, and time. I saved four pulses, and found none of my LHK values were recoverable. So I could only make one run, then had to copy the data before the next run. I'll post some data/graphs tomorrow, after I plot the data and make some graphs.

[California98Civic]

This is really interesting. Good luck, hey. But what about the torque measurement problem? You can control the sources of error jakobnev describes?

Originally Posted by SentraSE-R

Back to the drawing board. I'll need to daisy chain my UG to my SG to see LOD. The SG in Performance Mode shows distance, speed, and time. It leaves no way to display LOD.

When you save a performance run, it only saves distance, speed, and time. I saved four pulses, and found none of my LHK values were recoverable. So I could only make one run, then had to copy the data before the next run. I'll post some data/graphs tomorrow, after I plot the data and make some graphs.

[SentraSE-R]

There are some pretty good data collected by the SG performance mode every 0.4 seconds. First graph is a quarter mile run in standard US measurements. You can track the gearshifts by watching the fuel consumption blips.


The next graph is a 2nd gear pulse, using metric measures so I could use LHK. Unfortunately, the 24 second data recording time didn't let me record the complete 30 second glide linked to the pulse. It should be simple enough to measure the best pulse load and fuel consumption to pulse to speed, though.


Third graph is a 3rd gear pulse, also in metric. This pulse looks much softer than the 2nd gear pulse, because the distance traveled shrinks the LHK axis height. Also, the pulse time is longer.

[jakobnev]

Ok i got 179g/kwh@18km/h (+- five million per cent for various sources of errors)

(But i'm tired so i likely screwed up somewhere)

[rmay635703]

For a more realistic goal is it possible to have the SG
measure fuel consumption and distance in a small QTY such as ML and Meters so I can test different burn strategies over a fixed path and distance each day?

[SentraSE-R]

Unfortunately, MPG, GPH, LPH, and LHK are the only fuel consumption-related monitored performance gauges, and they're all crude measurements.

[SentraSE-R]

Miles/gallon and liters/hundred km are 1000 times larger than the ml and m rmay was asking about.