Specifications and Baseline performance

This baseline data was a side benefit of my visit to the EV drags at PIR on Aug 17th.

I made five passes,  with and without burnouts to get the performance data before conversion that can be compared to the performance after conversion.   All runs were similar and thus show it's basic capability. 

The shifting was always done at redline.   I figured, 5 drag runs was enough:

17-Aug-07 time PM R/T 60 feet 1/8 mile MPH 1000 feet 1/4 mile MPH
Run 1 6:48 0.379 2.46 10.7 65.68 13.875 16.518 85.2
Run 2 7:04 0.62 2.18 9.79 70.61 12.82 16.378 86.74
Run 3 7:10 0.654 2.443 10.35 67.91 12.948 16.046 85.82
Run 4 7:18 0.033 2.398 10.342 67.91 12.78 16.024 87.59
Run 5 8:09 0.06 2.412 10.385 67.36 13.01 16.11 86

 

The torque is nearly doubled with the new electric drive system so the clutch spring force will need to be doubled to prevent any slip from sheer torque levels transferred through the clutch, even though it will not even be used off the line. 

Also needed for better traction off the line, a limited slip rear differential to prevent wheel spin on one side.    This will make the vehicle a very capable drifter with all the torque available.  In first gear, with a little side force from steering, the rear end will break loose without the clutch when you put the pedal down agressively.

 

The torque and power curves of the original Internal Combustion Engine (ICE) performance overlaid with the electric motor performance:

           Pre conversion                                           Post conversion

            ICE performance                                        Electric performance

             Torque = 175 ft lb                                        Torque = 316 ft lb

             Power  = 185 HP                                          Power  = 268 HP

Until I have all the EV components specifications listed on this page, here is some additional information about the BMW: www.evalbum/1541

 

There is a significant difference in the off_the_line acceleration as the electric drive has full torque at 0 RPM vs. no torque at 0 RPM with the ICE.  With gas engines, some of the initial power is lost in the clutch as heat trying to control the traction during hard acceleration.  

No clutch is needed in the electric drive to apply full torque to the wheels off the line.   The trick will be pressing the pedal down at the right rate to prevent breaking the rear wheels loose initially, and getting to the full_power_applied point at the ~100 foot point. 

Once conversion is complete,  it will be re-tested at Portland International Raceway to compare to the result against the above data.

 

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