Burn out?!

[rainnw]

I just do a neutral drop with the pedal all the way down. The motor starts at a full 80kW.

Car in 'N', floor the accelerator, then shift into 'D'? Does that work in a LEAF? I need to try that...

Yes works great.

 

[mxp]

I just do a neutral drop with the pedal all the way down. The motor starts at a full 80kW.

Car in 'N', floor the accelerator, then shift into 'D'? Does that work in a LEAF? I need to try that...

Yes works great.

Err.... can you clarify that after you floor the accelerator, do you have to wait a couple of seconds (for the motor to spool up to 80kW) before shifting into 'D' ??

 

[planet4ever]

I don't believe your question is pertinent, mxp. If you were serious, then you're stuck in ICE thinking. Floored in neutral the motor isn't spinning at all (if the car is stopped), no matter how long you hold the accelerator to the floor. "Shifting" from neutral to drive doesn't do anything to the drive train; it just changes the electrical interaction between the inverter and the motor. Mind you, I'm not claiming that rainnw is lying. It seems quite plausible that the computer is limiting power at and close to zero speed, and it may be that starting with the pedal floored in neutral bypasses that limit.

Ray

 

[DaveinOlyWA]

True enough, but how long do you think a RWD car's rear tires get power before the car's weight shifts onto them? That is, how much time do the rear tires have to lose friction before the car's weight shifts onto them? One quarter of a second? Half a second? One second? Compare that to a FWD car's front tires, which will be unloaded the entire time the car is accelerating.

a fraction of a second. but that is all it takes. the angle or amount of torque in which friction becomes reduced (which is the same thing essentially) is much greater for a stationary object than a moving object

Here's a real easy test: if it's easier to burn out in a RWD car, it'd be harder to burn out in reverse in that same car, no? I.e. same car, but now as a "FWD" car. Or with a FWD car, it should be easier to chirp the front tires/burn out when accelerating backwards in reverse than when accelerating forward? Let me know what you find.

find me a car with identical gearing and torque and weight ratio in reverse as forward and i will try it

Finally, if FWD cars are superior at retaining traction during launch, why are all dragsters RWD?!

why do you use handles? for shovels, hammers, axes, etc? its for leverage.

why does a dragster have to be so long? why cant it be short like those slower, shorter funny cars?

there is a million "whys" and you need to ask someone else in the field because i dont "really" know why or care

but then again; have you ever seen one of those dragsters flip?? maybe those engineers dont understand leverage as much as they think they do

 

[aqn]

I just do a neutral drop with the pedal all the way down. The motor starts at a full 80kW.

Car in 'N', floor the accelerator, then shift into 'D'? Does that work in a LEAF? I need to try that...

Yes works great.

I tried it. While I failed to chirp the tires, let alone do a burn out, probably because the street where I tried it is a bit pebbly, the car did jump off a stand still much harder than just flooring it while in 'D'. Maybe I should do a few crude 0-60 runs with this method... Thanks for the tip!

 

[mxp]

I don't believe your question is pertinent, mxp. If you were serious, then you're stuck in ICE thinking. Floored in neutral the motor isn't spinning at all (if the car is stopped), no matter how long you hold the accelerator to the floor. "Shifting" from neutral to drive doesn't do anything to the drive train; it just changes the electrical interaction between the inverter and the motor. Mind you, I'm not claiming that rainnw is lying. It seems quite plausible that the computer is limiting power at and close to zero speed, and it may be that starting with the pedal floored in neutral bypasses that limit.

Ray

Haha! Thanks Ray. I was indeed thinking like ICE. :lol:

I have never interacted with the accelerator ever in N so when I read this post, in the back of my head, I thinking along the lines of an SMG equipped BMW M3 which has "launch mode" for a quick acceleration.

 

[rainnw]

I just do a neutral drop with the pedal all the way down. The motor starts at a full 80kW.

Car in 'N', floor the accelerator, then shift into 'D'? Does that work in a LEAF? I need to try that...

Yes works great.

I tried it. While I failed to chirp the tires, let alone do a burn out, probably because the street where I tried it is a bit pebbly, the car did jump off a stand still much harder than just flooring it while in 'D'. Maybe I should do a few crude 0-60 runs with this method... Thanks for the tip!

It depends on the pavement, road conditions, vehicle incline, etc. The neutral drop will increase your chances.

 

[DaveEV]

Anyone see if holding their foot on the brake / gas at the same time then letting off the brake works?

 

[DaveinOlyWA]

i did it in Eco mode once without really trying. i accelerated out of a roundabout and spun my tires on the railroad track crossing and squawked em on the other side.

 

[TLeaf]

Though not an electric motor expert, I wonder if part of the problem here is that the LEAF's motor is not a DC motor, which does have 100% torque off the line, but a synchronous AC motor which doesn't develop maximum torque until somewhat higher motor speeds are reached. True enough, the motor controller can adjust the voltage and torque seen by the motor to keep the motor operating at closer to max torque, but we're still dealing with a bit of a deficit to start with. Then again, perhaps some of it is Nissan's desire to produce either: a) a "safer" car (wanton burn-outs not being good for safety), b) a "greener" car (wanton burn-outs not being good for efficiency), c) a longer lasting battery (need to double-check how many C's can be pulled), and/or d) a cheaper car (lower cost components, as already mentioned).

As an aside, I wonder why the neautral-drop method would result in different acceleration if the answer above is c or d. More likely the capability is there, but Nissan programmed in a different voltage/frequency curve in this situation for some reason. I wonder what the Nismo program looks like....

Has anyone taken a LEAF on a dyno yet?? I know of someone who might be able to help if there's an interest...

 

[aqn]

Though not an electric motor expert, I wonder if part of the problem here is that the LEAF's motor is not a DC motor, [...]:
c) a longer lasting battery (need to double-check how many C's can be pulled), and/or d) a cheaper car (lower cost components, as already mentioned).

As an aside, I wonder why the neautral-drop method would result in different acceleration if the answer above is c or d.

I have no clue! My "butt dyno" definitely told me that a neutral drop made the LEAF just about leap forward, compared to just mashing the accelerator pedal while already in 'D'.

Has anyone taken a LEAF on a dyno yet?? I know of someone who might be able to help if there's an interest...

Do it, do it, do it!!!

Come to think of it, dynos pick up RPM information via an inductive pick-up clipped onto a car's ignition wire. How would a dyno work with an EV? Maybe it just counts wheel RPM and derive the motor RPM from that since the transmission is fixed ratio?

Mustang announced a dyno that workes with hybrids and EVs. In any case, a Google-ing for "dyno electric vehicle" proved to be an entertaining time-waster! Thanks for bringing up the subject of dyno-ing!

 

[DaveEV]

If the dyno isn't able to read RPM through spark plugs, they can simply plot wheel-horsepower vs ground-speed.

 

[gbarry42]

the car did jump off a stand still much harder than just flooring it while in 'D'.

We were wondering a few months back (Tony's disassembly) why the motor mounts were so big. Maybe this is a clue

need to double-check how many C's can be pulled

Well, if 24kW on a 24kWh pack is 1C, then 80kW would be 3.3C. If I understood the C in your question.

 

[kballs]

the car did jump off a stand still much harder than just flooring it while in 'D'.

We were wondering a few months back (Tony's disassembly) why the motor mounts were so big. Maybe this is a clue

This is all in your head (not calling you a liar, but you are probably imagining it's faster). I tried a neutral drop with the accelerator pedal to the floor tonight and it does not jump off the line any harder than just stomping it in D and still doesn't hit full power until >20mph.

 

[LEAFfan]

I've been able to chirp the tires from a standing start in ECO and D, traction control ON, without any problem. I also did it twice in the Drive Tour LEAF, once in ECO and once in D with the traction control on.

 

[aqn]

the car did jump off a stand still much harder than just flooring it while in 'D'.

We were wondering a few months back (Tony's disassembly) why the motor mounts were so big. Maybe this is a clue

This is all in your head (not calling you a liar, but you are probably imagining it's faster). I tried a neutral drop with the accelerator pedal to the floor tonight and it does not jump off the line any harder than just stomping it in D and still doesn't hit full power until >20mph.

Well, yes, I did mention that I was using my "butt dyno". OTOH, please allow me to say that it's you who's imagining that that a neutral drop is not quicker than flooring the accelerator pedal in 'D'.

Hopefully someone will do 0-60 runs using both methods soon...

 

[Dino]

Though not an electric motor expert......
Has anyone taken a LEAF on a dyno yet?? ..

Tleaf did
http://www.mynissanleaf.com/viewtopic.php?f=27&t=5323&hilit=dyno&start=20#p124174" onclick="window.open(this.href);return false;

My guess is that the torque curve is programmed.
http://en.wikipedia.org/wiki/Variable-frequency_drive#VFD_operation" onclick="window.open(this.href);return false;