Electric Motorkhana and khanacross car

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galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Wed, 24 Apr 2019, 11:38

Here are some recent pics
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galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Wed, 24 Apr 2019, 11:41

and here are a few in the higher speed configuration
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Bryce
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Re: Electric Motorkhana and khanacross car

Post by Bryce » Wed, 24 Apr 2019, 15:31

As a former motorkhana competitor through the RCCV: I would have been interested but apologies, I never noticed your posts.
Love the idea of an electric motorkhana special. That car must have scared a few/all of the fossil competitors!
Cheers
Bryce
AEVA Vic Branch Secretary
AEVA national newsletter editor
Current EV drives: 2011 Leaf, 2001 Berlingo conversion
Past drive: 2011 Blade Getz
Past Conversions: DC Berlingo, AC Berlingo, AC Sprinter

galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Fri, 26 Apr 2019, 07:38

Thanks. The torque is great for motorkhana as it is for other standing start forms of motor sport. I have struggled to strike a good suspension setup though. It is starting to come good.

My design is a bit of a compromise as I am not willing to give up hill climbs and khanacross in order to be outright competitive in motorkhana. So the resulting car is a bit big to be an outright contender for Motorkhana at a national level.

The main advantage with ICE motorkhana cars are packaging in the design. They can fit a proportionally big motor without needing a big fuel tank to feed it. In an electric motorkhana car you can certainly fit a big motor but then where do you mount the batteries to supply the required power. Of course you could scale it all down but it gets increasingly difficult to find enough space for the batteries. Because in a smaller vehicle the driver's weight becomes a bigger proportion of the total. Therefore you can't afford to reduce the motor and battery too much or you risk losing the torque advantage off the line. Mine is 450kg which makes it about 570kg with driver and 1000amps worth or torque. I do think it would be possible to build a motorkhana specific EV at around 350KG making the total 470kg with driver but I would need to reduce the power to around 600amps which roughly means a 40% reduction in acceleration off the line. For an outright motorkhana car ultra capacitors may be a good option as it would then be possible to achieve the same current and torque without the weight penalty.

galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Fri, 10 May 2019, 07:12

Hi all, I will be competing at the Mt Cotton Hill climb tomorrow. It is an informal day but should still prove interesting with the torque of the Batt mobile. I haven't had much track time at Mt Cotton and it has been quite a few years. I will go on record as saying the following:
A sub 50 second run would be acceptable. A 46-49 second run would be good. A 43-45 second run would be excellent. Anything quicker that 43 seconds would be amazing.

galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Mon, 13 May 2019, 08:41

I had a great day at the Mt Cotton hill climb. I only managed a 52 second lap which isn't too impressive but not too bad for a first attempt. I need to learn the track and get brave to achieve better times. But the main issue was brake bias. I need more brake power in the back. I had to brake way too early to make it through the tighter corners. This cost me plenty of time. I am investigating conversion options for the rear brakes.
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Bryce
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Re: Electric Motorkhana and khanacross car

Post by Bryce » Mon, 13 May 2019, 08:57

Well done! And now the big question: Did you have FUN?

Cheers
Bryce
AEVA Vic Branch Secretary
AEVA national newsletter editor
Current EV drives: 2011 Leaf, 2001 Berlingo conversion
Past drive: 2011 Blade Getz
Past Conversions: DC Berlingo, AC Berlingo, AC Sprinter

galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Tue, 14 May 2019, 08:58

Absolutely. It is a hoot. Even after shoving my nose in the nuts I cam away smiling. It might not have been the case if there was damage. Keeping the cost low and having fun are my main two objectives. Times and results are a secondary consideration. I would love to attend Mt Cotton more frequently but unfortunately they generally run on Saturdays which is a problem for me. The fact that I was able to maintain good corner speed was very satisfying. But the best outcome from the day was the identification of my key weakness which is insufficient rear brake power. It gives me confidence I can improve leading up to future events.

francisco.shi
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Re: Electric Motorkhana and khanacross car

Post by francisco.shi » Tue, 14 May 2019, 10:43

Could you use regen braking to help the rear brakes?

galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Tue, 14 May 2019, 11:07

In theory yes. Unfortunately I don't have regen in my system.

galderdi
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Re: Electric Motorkhana and khanacross car

Post by galderdi » Tue, 14 May 2019, 11:08

Here are some videos from Saturday:




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