Originally Posted by RedLS6

This guy makes the mistake of dynoing in 5th gear; then he does a 4th gear pull, then 3rd; results are about as expected as the power picks up slightly in 3rd probably due to motor back-emf being reduced at 3rd gear speeds.

The electric motors have 3 main operating regions as speed increases, assuming no loss in battery voltage; off-idle from a start up to the motor's base speed, constant torque; as motor speed increases further this constant torque region is followed by linear torque drop with constant power, further speed increases are followed by back-emf power drop. Then. specific to the E-Ray is the 150mph cutoff.

I think the various dyno's have shown all of these regions. If anyone gets a full recording of the dash-displayed motor power from 0-150 then should be able to roughly pick out all of these operating transition points just from the dash. For the E-Ray, gear selection on the dyno will be important to capture what the motor is doing at any given vehicle speed.

https://www.youtube.com/watch?v=w7KD..._HB2XZ8&t=679s

Originally Posted by 3LZR21U

Battery being more depleted during the return leg doesn't matter unless it is literally choking power output from the motor.

I do not believe that even with the limited capacity of the batteries in the ER, that the motor is capable of blasting through the entire charge 30 seconds. I think GM intentionally sized the motor for output of an intended mean duration--based on that battery capacity. So the down leg may go from 80-60% and the return leg may go from 60-30%. But you still have battery and the motor wouldn't be starved of power.

Originally Posted by PRE-Z06

You’re assuming they allow full power to the motors at decreased battery capacity. I assume it drops as it’s lowered and not in a linear rate either necessarily. At the same time the output from the motor drops as speed increases and aero drag increases exponentially as well, so to me all those things add up to why the E-Ray isn’t efficient at higher speeds. On a road course there may be time for the battery to recharge in the corners, but the U-Drag isn’t that kind of test. I’d like to see back to back laps on a road course to see the difference in lap times, though heat may be a factor in the results.

Originally Posted by PRE-Z06

I get the back emf, but not sure how to assign it a value. In the case of the U-drag my point was the battery is being depleted the whole 30+seconds expect during the braking and the corner which means the return run it’s making less power regardless of the increased drag from wind direction changing from tail to head which exacerbates the delta even more. .

Originally Posted by RedLS6

If it's a decent battery it should lose 1-2% of its voltage going from 80% down to 40-30% and increasing past that, so this isn't a huge impact by itself but it is an impact - and I don't think we know exactly how much the software is beginning to current-limit as 20% is approached. I think we saw during the road course test that performance begins to suffer as the battery depletes which is expected. GM really hasn't released much detailed information about this drive system, past the "general public basics". Also, the regen becomes less efficient as speed increases, as back-emf works against it and the motor can only regenerate kinetic energy and can't regenerate power gone to aero losses.

Originally Posted by PRE-Z06

You’re assuming they allow full power to the motors at decreased battery capacity. I assume it drops as it’s lowered and not in a linear rate either necessarily. At the same time the output from the motor drops as speed increases and aero drag increases exponentially as well, so to me all those things add up to why the E-Ray isn’t efficient at higher speeds. On a road course there may be time for the battery to recharge in the corners, but the U-Drag isn’t that kind of test. I’d like to see back to back laps on a road course to see the difference in lap times, though heat may be a factor in the results.

Originally Posted by 3LZR21U

My read was that the return leg motor power was more due to the ER being moving already--vs from a dig. You're right though, we don't know what the mapping is. If they were right and it was at 50% after the first complete run--I'm inclined to think that artificial "throttling" of the motor wasn't a factor. If I were mapping something like hybrid drive from scratch, I'd try to put the taper at 40% and ramping down until almost nothing at 20%. Anything higher than 40% and you'd end up spending too much time with throttled output. And the ER is designed to both rapidly charge and discharge (according to the engineers).

Originally Posted by Z0HS1CK

That video is coming up soon for sure.

It's not competition. Both cars are great for their own right but i know GM won't let the Z lose, especially if any cornering is involved. It will make them look bad. The ERAY will showcase it's great acceleration to 60, and z06 should pick up the slack everywhere else.

Can't wait to see the video.

Originally Posted by PRE-Z06

The Z06 was quicker time wise to the finish, so no doubt it wins. I’d prefer they use a base Z06 and ZER E-Ray, so they’re on the same tires and aero package.