Power Graphs and Calculations v2

Updated 2011-01-16: corrected data, added details

Official graphs

These are official Boxer Diesel power graphs from Subaru press info, dated 2008:

Digitizing with Inkscape, zoomed in, bitmap layer in background:

Saved as SVG (Inkscape’s default format) coordinates are plain readable. Some conversion had to be done – SVG origin is top left, scaling, relative coordinates etc.

Digitized torque data


Engine Speed [1/min],Torque [Nm]
1193.55,202.578
1313.36,249.619
1443.78,298.872
1472.12,307.111
1518.49,317.562
1555.84,326.697
1575.2,334.011
1617.03,340.603
1669.37,345.07
1736.66,347.988
1808.8,349.379
2383.36,349.662
2421.46,349.484
2461.55,348.549
2522.98,346.099
2650.91,340.182
2798.88,332.502
2994.03,324.842
3300.6,312.663
3478.52,304.245
3661.72,288.783
3787.83,275.768
3830.03,268.687
3878.16,261.977
4129.99,232.604
4232.87,220.772
4372.64,202.82
4419.5,195.276

Function plot, linear interpolation:

Digitized power data


Engine Speed [1/min],Power [W]
1201.24,25496.7
1419.95,43784.2
1565.12,55739.5
2025.77,73824.5
2310.73,84411.4
2376.1,86717.
2436.11,88110.1
2548.37,91706.8
2941.28,100369.
3125.55,104148.
3278.06,107158.
3442.58,109944.
3514.2,110805.
3589.68,110856.
3690.33,110450.
3835.49,108829.
3947.75,106904.
4058.08,104219.
4149.05,100927.
4261.31,95607.5
4347.44,91681.5
4396.8,89908.4

Since power can be calculated from torque and angular velocity, this can be used to check the official power curve. Looks like someone put “lipstick” on the last part of the curve…

Drive force

After applying some math (torque curve, vehicle speed vs. RPM, gear ratios)…

View above graph as SVG (best quality).

Theoretical shift points

Calculated intersection points (drive force equality solutions), slightly rounded:

v [km/h] Gear1 RPM1 [1/min] Gear2 RPM2 [1/min]
75 2 4340 3 2630
116 3 4070 4 3010
151 4 3920 5 3170
181 5 3800 6 3340
Advertisements

One response to “Power Graphs and Calculations v2

  1. Pingback: EE20 facts! - Page 2 - Subaru Forester Owners Forum

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s