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Aussie Electric Autocross car by Z owner

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#1 galderdi

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Posted 28 February 2017 - 10:18 PM

Hey guys,

 

It has been a while since I posted on this forum. I still own and love my Zs. But I have been distracted on other projects.

 

I have built the first electric motorkhana / khanacross car in Australia. It has been competing for 12 months now and is just starting to realise it's full potential.

 

The chassis is home made from the ground up. most of the mechanicals are mostly from a Nissan Pulsar (small front wheel drive hatch).

The car is front wheel drive because they have a slight advantage over rear wheel drive in this form of motorsport.

The motor is an Advanced DC 9 inch. This type of motor is usually used for converting a 1200KG road car. So in my 500kg car it goes quite nicely.

The controller is a Zeva 1000amp unit (although so far I have only tested it to 800amps)

So far the peak power I have seen has been 67KW. But its the torque that is the real advantage of these motors with around 440nm from 0 revs.

The batteries are 170v lithium Ion from a Chevy Volt. The total capacity is 7KWH and it lasts a full day of racing for me.

 

I'll post some pics and videos in a minute.



#2 galderdi

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Posted 28 February 2017 - 10:51 PM

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#3 galderdi

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Posted 28 February 2017 - 10:56 PM

This is one of my favourites. It is using a 360 degree camera. It is best viewed using a mobile device.
 


#4 galderdi

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Posted 28 February 2017 - 11:00 PM

Here is a video from my test session with GPS. Just doing a bit of modified slalom
 


#5 galderdi

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Posted 28 February 2017 - 11:03 PM

This was a slightly higher speed test. I chickened out before reaching top speed because the rear alignment was all wrong. I have since aligned the rear so hopefully next time I won't need to hold back.
 


#6 galderdi

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Posted 28 February 2017 - 11:07 PM

Its still a work in progress.

But you can see all my other videos by searching "Full Charge Motorsport" on Youtube. You can also track my progress on Full Charge Motorsport on Facebook. Please feel free to let me know what you think.


Edited by galderdi, 28 February 2017 - 11:08 PM.


#7 galderdi

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Posted 07 March 2017 - 11:10 PM

My next event is a motorkhana this Sunday (March 12) at the back of the Willowbank Drag strip. The competition will be under way between 10 and 3. Spectators are welcome and free. If you are in the area feel free to pop by and check the action and say Hi.



#8 seattlejester

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Posted 08 March 2017 - 12:00 AM

Pretty cool! Good luck next Sunday!



#9 galderdi

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Posted 28 March 2017 - 10:52 PM

I was competing in the Queensland Motorkhana championship rounds 1 an 2 over the weekend in Gladstone. The car was great for the first half of Saturday but then the heat got to me and I muffed a couple of the tests. I still managed 6th place outright for Round 1. But the gearbox developed a vibration. So I planned to take it easy on the Sunday. I often started in 2nd gear with higher current in an attempt to reduce revs. In the end I managed 3rd outright on the Sunday and I was only 0.27 seconds off 2nd place. All in all I am very pleased as the car isn't suited to motorkhana. It is more of a khanacross car. I can't wait until May 21 to test it's true potential.



#10 seattlejester

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Posted 28 March 2017 - 11:33 PM

Question. So the DC motor is connected to the pulsar running gear like the trans and such? Do you still run a clutch and such if you are shifting? Or do you mean shifting an automatic?

 

I've always wondered how a manual trans holds the large instant torque.



#11 galderdi

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Posted 30 March 2017 - 04:26 PM

Hi,

 

Very good questions. There are a lot of answers. Hopefully I won't overlook anything.

 

A lot of people with road cars converted to electric run the motor directly to the diff. This works well but does sacrifice some of the potential acceleration. Many road car owners are happy with that outcome. But for my sport I need the instant acceleration. So I opted to retain the gearbox. It is a front wheel drive gearox with the diff included.

 

I do two main forms of motorsport. Both are standing start time trials, so the torque is very important. Motorkhana is extremely tight and technical with lots of handbrake turns, some reversing and a top speed of around 60kmph/35mph. Khanacross is much like autocross with no reversing, slightly more open corners and a top speed of around 100kmph/60mph. 

 

I do run a clutch but for motorkhana I only shift from 1st to reverse and I am stationary at that point so no need for the clutch. Launching is done from 0 revs so no need for the clutch there either. But for khanacross I need to start in 1st and run through the gears up to 3rd (maybe 4th) so I need to use the clutch between gears.

 

As far as taking for the force I have some theories.

  • The clutch is the "fuse" between the power of the motor and the weight of the vehicle. The drive train needs to handle the same two factors. So if one or both are increased the clutch and drive train need to be strengthened. But I have increased the torque and decreased the vehicle weight. So in my opinion these two changes cancel each other out (at least to some degree).
  • Another factor is the way the power is engaged. In a petrol car to get acceleration you rev the motor and then drop the clutch, suddenly introducing a mismatch between the drive train and motor. In my opinion it is this mismatch that places the drive train at risk. With an electric motor the motor and drive train are always matched whenever the power is applied. So even though people talk about instant torque I beleive the electric motor torque is applied in a more controlled way and avoids the snap of dropping the clutch. In other words I don't think it is truely instant. Even if you do drop the clutch with an electric motor it is generally done without the foot on the peddle so there is no power being pushed through the motor (it is usually just spinning as a result of inertia). So the drive train equalises without any power, then after the clutch is dropped and the peddle is pressed the power smoothly accelerates the car again.
  • The tyres are another "fuse", if too much power is applied the tyres are the first thing to give way (in the form of tyre spin). Granted I have bigger and stickier tyres which does place greater strain on the drive train. But even so I have shown the drive train can handle enough power to spin even my biggest/stickiest tyres.

So all in all I do have some nerves about the drive train holding up but I think it will be fine.

 

Let me know if I missed anything.

         

 

 



#12 seattlejester

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Posted 30 March 2017 - 09:00 PM

That makes quite a bit of sense! Thanks for the detailed explanation. 



#13 galderdi

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Posted 30 March 2017 - 10:22 PM

It turns out I only missed 2nd place on Sunday by 0.27 seconds.

 

I have also now had the chance to pull the car apart to investigate the vibration.

 

There were two problems. One probably caused the other but I am not sure which is which.

Two of the springs popped out of the clutch plate.

The retainer bolt that secures the Flywheel and adaptor to the motor output shaft snapped.

 

Either of these propblems could have either caused the vibration or resulted from the vibration. I suspect the retainer bolt as it was way too easy to remove the remaining portion of bolt, indicating it worked it way loose.

 

The good news is that I should have it all fixed over this weekend in time to compete at the next event next weekend and beat some Porsches and Clubmans.



#14 galderdi

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Posted 02 April 2017 - 07:30 PM

I have replaced the clutch and reconstructed the car. I have also reduced the front camber by 1 degree (from neg 3 to neg 2 degrees). I was surprised by the extra resistance I feel when steering. I am really looking forward to giving this a go on Sunday.



#15 galderdi

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Posted A week ago

Hi again, The last event didn't go to plan. I had a major suspension failure. Basically it was a design flaw. I hadn't anticipated the vertical force resulting from the twisting motion of the lower control arm within it's mount. The result from 18 months of competition was the mount was flexing and eventually gave way. I have replaced the mounts and reinforced them so they can nolonger flex.

 

I am all ready for the event this Sunday. This is a khanacross which I have been waiting months for. Khanacross is perfect for this car so I am aiming for great results.

 

If anyone local is interested it will be held at the back of the Willowbank drag strip. Spectators are free. Competitors are also welcome and are $45 per entry assuming you have a CAMS license and a Rally extension from your CTP provider if you have a road registered car.  



#16 galderdi

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Posted A week ago

I had the khanacross yesterday. The car was solid but the combination of car /driver weren't the quickest on the day. There is still room for improvement. I'll post some videos shortly






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