[Fivedoor]

Hey guys,

Just for fun took the Bolt EV to Memphis International Raceway for test and tune last night after work. I arrived with around 2/3 of a charge in the battery. Temperatures in the mid 70's and for some reason I didn't even think to turn on data logging!

First run was just me, nobody in the other lane.
R/T . . . . . . . . 0.379
60' . . . . . . . . 2.654
330' . . . . . . . 6.828
1/8 . . . . . . . . 10.177
mph . . . . . . . 73.50
1000' . . . . . . 13.083
1/4 . . . . . . . 15.557
mph . . . . . . . 90.57

Second run I was beside another street car, not sure what it was, didn't get a good look. You can see from the time slip that we were pretty evenly matched with me being a bit faster, but he had a better reaction time so I was playing catch-up the whole 1/4 mile and he finished .0188 seconds before me!

R/T . . . . . . . . 0.728
60' . . . . . . . . 2.536
330' . . . . . . . 6.688
1/8 . . . . . . . . 10.037
mph . . . . . . . 73.47
1000' . . . . . . 12.942
1/4 . . . . . . . 15.418
mph . . . . . . . 90.53

Later,

Keith

 

[Dimitrij]

For dummies, what are all these whimsical figures? I am guessing that 1/8 is the time you took to do 1/8 mile, and E.T. is extraterrestrial

 

[NY-Rob]

Nice!


Any idea what the 0-60mph time was?

It's reported to be in the high 6's IIRC....

 

[GlenandhisBolt1!]

The Bolt tops out at about 93 mph. It looks like you reached top speed before you crossed the 1/4 mile light. It looks like you weren't topped out at the 1/8 mile (660 foot) light, but you may have been there at the 1000 foot light.

Motor Trend reports a zero to 60 time of 6.3 seconds. Chevy advertises a time of 6.5 seconds. Both of these times are almost certainly using the standard 'one foot' start technique: the vehicle 'stages' one foot behind the start light, so it gets a one foot head start before the timer starts ticking. This makes a huge difference on an EV, as an EV develops maximum power and torque from a dead stop, quite unlike an ICE vehicle. For example, a Tesla Model S is said to be going 6 mph after one foot.

 

[NY-Rob]

^ it is also possible that battery SOC has some effect on acceleration.


Would be interesting to see 0-60mph times from a 100% SOC battery and a 15% SOC battery.

 

[dbostrom]

^ it is also possible that battery SOC has some effect on acceleration.

I read exactly that just a few days ago, in a discussion of the vehicle's battery development including the engineers who steered the work. But where? Dang. It may have been an SAE paper I linked to here in a another thread. But anyway, if memory serves correctly the car should indeed be at full charge in order to give its best showing.

 

[hatchy]

Yep, at 100% SOC my dash shows 160kW peak. It falls off rapidly with discharge.. anything less than 7/8th full and for sure you will not get the full 160.

That 60 foot is terrible. If your car's traction control is limiting your power like my car does, it makes sense it would be terrible.... These cars should be able to run high 14's with some good tires and no limiting.

 

[Edchris]

There is some YouTube somewhere where a guy did repeated drags in his Bolt. The power did indeed fall off as SOC decreased.
IIRC he turned traction control off, then modulated the accelerator just to the point of tires breaking loose.

 

[NewsCoulomb]

Any idea what the 0-60mph time was?

It's reported to be in the high 6's IIRC....

With a full battery, it should be close to 6.2 seconds 0-60 mph (according to Motor Trend).

Here is a breakdown of how the Bolt EV's power output decreases as the battery capacity steps down:

https://youtu.be/jFzHrmpp4Eo

 

[Fivedoor]

So looking at the NewsCoulomb experimentation, I was probably at or near the rated 150 KW, 10 KW less than I would have had at 100% SOC.

If the EA CCS station in Memphis goes on line perhaps I can do some runs at or near 100% SOC in the near future.

Later,

Keith

 

[Fivedoor]

Yep, at 100% SOC my dash shows 160kW peak. It falls off rapidly with discharge.. anything less than 7/8th full and for sure you will not get the full 160.

That 60 foot is terrible. If your car's traction control is limiting your power like my car does, it makes sense it would be terrible.... These cars should be able to run high 14's with some good tires and no limiting.

Yeah, that 60' is nothing like the 1.7's I used to get in my old EVO. I want to experiment with tire pressure, and different launch techniques. I went right after work, thus the low SOC and only getting two runs in before the end of session.

Keith

 

[NY-Rob]

Wow, big difference in HP output based on battery SOC according to the youtube results..


100% SOC = 160KW = 214HP
10% SOC = 134KW = 180HP


So if your going to race/test performance... charge to full.

 

[NY-Rob]

.... I want to experiment with tire pressure, and different launch techniques.

Interesting experiment...


On one hand lowering tire pressure increases surface contact area for better traction, but also increases rolling resistance.
Raising pressure lowers rolling resistance, but lessens surface contact area resulting in less traction.


Where is the sweet spot... 38PSI maybe?

 

[NewsCoulomb]

So looking at the NewsCoulomb experimentation, I was probably at or near the rated 150 KW, 10 KW less than I would have had at 100% SOC.

If the EA CCS station in Memphis goes on line perhaps I can do some runs at or near 100% SOC in the near future.

Later,

Keith

Wow, big difference in HP output based on battery SOC according to the youtube results..


100% SOC = 160KW = 214HP
10% SOC = 134KW = 180HP


So if your going to race/test performance... charge to full.

Yes, I think you're going to want to be 90-100% for any drag/acceleration runs.

Also, a note: That 160 kW is power coming from the battery, so there are losses. I don't know if it's a full 10 kW loss, but that might be about right. Maybe I missed some Bolt EV dyno runs, but it would be interesting to see how they align. Assuming it's a 10 kW loss from battery to motor output, at max SOC, the Bolt EV is likely putting down 190+ hp at the wheels.

 

[NY-Rob]

^ maybe check with a local community college that has an Automotive Tech course. They will likely have a dyno and would probably love to put an EV through it's paces for educational purposes.

 

[hatchy]

Depends on your track's level of surface prep, but if the Chevy electronic throttle limiting won't let you spin 35psi tires during a run, running them lower isn't going to help anything.

If there were a way to turn the throttle limiting completely off, the pressure for best ET could be like 20psi. We probably will never know, but it would take a **** of a lot of loss on the top of the track to negate the gains from a good launch. Can you imagine getting the full 160 from 0.001 seconds after you hit the pedal? Now that would be fun...

I think the whole 180hp to 214hp thing is why they rated the car at 200hp, if you average what you get out of the skinny pedal, its about 200hp. I'd swear my peak power vs SOC started tapering off more quickly lately compared to when I first got the car. I'm not sure if its due to an update, or battery wear or what. It used to hold 160 down lower in to the SOC.

 

[Sean Nelson]

Can you imagine getting the full 160 from 0.001 seconds after you hit the pedal? Now that would be fun...

Someone needs to develop a camera-based app to do this...

 

[taylorsareus]

Lowering the air pressure isnt likely to help, much more likely to make it spin more. These are street tires, hard street tires, not drag tires. Lowering the air pressure will make the center cup in while the sidewall stays rigid. This lowers the contact pattern.
You are already hitting the speed limiter. Keep in mind its not like a light switch, you should notice a sagging feeling about 89-90 mph. Also drag strip speeds are calculated in the last 66 feet of the track, not measured in one shot. Since you are accelerating that means you are actually going faster at the end than your timeslip shows.
Traditional things racers talk about like temperature, density altitude, etc have little to no effect on EV's

What Bolts need to really fly is control over the dump rate and to increase/remove the speed limiter.

 

[Fivedoor]

Went back to the track tonight with around 97.5% SOC.

Best run was as follows:

60' . . . . . . 2.531
330' . . . . . 6.612
1/8 . . . . . . 9.891
MPH . . . . . 75.44
1000' . . . . . 12.728
1/4 . . . . . . . 15.142
MPH . . . . . . 91.94

I will post time slips later.

Keith

Middle one is the slip I broke down in the text.

 

[NewsCoulomb]

Nice. You cut almost a half second off the 1/4 mile time.

What altitude are you at? I might try a couple of passes one of these days (if I can ever find the time). It would be interesting to see the differences 5 lb lighter rims make.