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Hi guys. Completely new to this. I compete in the largest motor sport in the uk Autograss. The sport has 10 classes of cars ranging from standard 1000cc cars to purposely built open wheeled cars with 2 hyabusa engines strapped together. Some of these vehicles produce 1000bhp/tonne. Nobody has yet entered an EV within the sport and I'm sirously thinking about it. The track is an oval dirt track approximately 1/3mile long. The amount of laps depend on conditions. Races usually last around 5 minutes and are usually full throttle for around 90% of the time. There are 4 races per meeting but often have reruns, so we need to allow for 6 5minute races really. Weight is a big factor which I'd have to concede if I go down this route. I'm hoping that the governing body will allow me to enter into class 5, which is 1400cc 8v class. All heavely modified rear engined Austin minis, usually with Vauxhall or Citroen engines. I have build a number of these cars from scratch, the latest is a "lift off bodied" mini pickup with a tuned volvo 2.3 T5 rear mounted, all on a self built chassis. Our fabrication and mechanical knowledge is good but I have absolutely no idea about EVs. I need upwards of 200 Nm of torque and need to be geared to do around 65mph. Any advice please. Needs to be a budget racer. I've had a couple of ideas. There are a number of rwd axles I could bolt a single motor up to, to achieve the required gearing, and that would mount quite easily. But any ideas on hardware or anything else, will be appreciated. Thanks in advance.

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If you are doing a lightweight chassis a Nissan Leaf motor and Trans might be the ticket. They have the torque you need and several people are engineering motor controller solutions around factory equipment right now. They are open diff-do you use a spool? If so, welding the factory setup might work.
 

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I'm hoping that the governing body will allow me to enter into class 5, which is 1400cc 8v class. All heavely modified rear engined Austin minis, usually with Vauxhall or Citroen engines. I have build a number of these cars from scratch, the latest is a "lift off bodied" mini pickup with a tuned volvo 2.3 T5 rear mounted, all on a self built chassis. Our fabrication and mechanical knowledge is good but I have absolutely no idea about EVs.
In a quick reading of the summary descriptions, the rules seem to be very specific about configuration and engine characteristics, without broader limits such as weight. Since the engines used by all other competitors are heavily limited, it would be reasonable for the organizers to set some sort of limits on an EV... although they might say "do what you want" assuming that nothing you can build will be competitive, and that having an EV will be a publicity advantage. It would be good to know with some certainty before committing to components.

I need upwards of 200 Nm of torque and need to be geared to do around 65mph. Any advice please. Needs to be a budget racer. I've had a couple of ideas. There are a number of rwd axles I could bolt a single motor up to, to achieve the required gearing, and that would mount quite easily. But any ideas on hardware or anything else, will be appreciated.
Stating a torque requirement assumes a gear ratio. Your actual functional requirement is torque at the wheels, and whether that is achieved by a 200 Nm motor and 4:1 gearing or 50 Nm and 16:1 gearing (both examples of 800 Nm to the wheels) doesn't matter. The motor does need to effectively cover the resulting motor speed range.

Few production EVs run overall gearing as low as the reduction offered by just the final drive ratio of an available light vehicle rear drive axle. I think that you will likely want an unusually high-torque/low-speed motor (the Chevrolet Spark motor is a good example, but obscure), or an additional single-speed reduction gearbox.

It appears that Class 5 would allow any motor and drive axle position combination, meaning that instead of using some sort of axle from a front-engine/RWD car, you could use the motor and transaxle (gearbox with differential) from a production EV, mounted in the rear with the hubs and suspension of a RWD vehicle with IRS. I assume that you need some sort of limited-slip differential, which would take some custom retrofitting with any EV transaxle.
 

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My plan was to approach the governing body NASA, to see if they are happy for me to enter class 5 as an experimental car. They have allowed this sort of thing before on 1 season trials. If they aren't happy with this, it would have to be class 7 which is unlimited rwd class. Mainly 2 motor bike engine class, but it has the odd car motor like our volvo t5. LS1 cheveys and supercharged Honda vtechs are also quite common. They say it's unlimited but no2 is not allowed throughout the sport, and motorbike engines have to be normally aspirated. I really don't think I could be remotely competitive in this class, that's why I'm looking at class 5. There is a risk they will not allow a ev anyway, as the scrutineers are concerned with the amount of electricity that could potentially arc onto the chassis in a major incident.

If I were going to mount the engine side-on, like a fwd configuration, I would probably use an autograss drivebox. This is just a single geared box that allows motorbike engines to convert from a cog, to driveshafts. You can alter the hearing inside them to suit the set up, or even the track length. There is no need for a gear change. The non-torquey high reving bike motors need a gearchange up the first straight, but then it's 1 gear to the end.

I'm hoping to get a plan together of what I would roughly build, and then go to NASA before construction to see if they allow it. So I need to put a component list together of what I can afford, and most importantly be competitive, and have the range. So any advise would be good. I was looking at this motor originally

http://www.go-ev.com/PDFs/002_05_06_WarP_11_Sales_Sheet.pdf

That was only because that seamed to have a decent amount of torque and is affordable. However, a second hand early Prius battery is only around £400. So maybe that would be a starting point. I really don't know how is best to go about it.
 

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Discussion Starter #7
My plan was to approach the governing body NASA, to see if they are happy for me to enter class 5 as an experimental car. They have allowed this sort of thing before on 1 season trials. If they aren't happy with this, it would have to be class 7 which is unlimited rwd class. Mainly 2 motor bike engine class, but it has the odd car motor like our volvo t5. LS1 cheveys and supercharged Honda vtechs are also quite common. They say it's unlimited but no2 is not allowed throughout the sport, and motorbike engines have to be normally aspirated. I really don't think I could be remotely competitive in this class, that's why I'm looking at class 5. There is a risk they will not allow a ev anyway, as the scrutineers are concerned with the amount of electricity that could potentially arc onto the chassis in a major incident.

If I were going to mount the engine side-on, like a fwd configuration, I would probably use an autograss drivebox. This is just a single geared box that allows motorbike engines to convert from a cog, to driveshafts. You can alter the gearing inside them to suit the set up, or even the track length. There is no need for a gear change. The non-torquey high reving bike motors need a gearchange up the first straight, but then it's 1 gear to the end.

I'm hoping to get a plan together of what I would roughly build, and then go to NASA before construction to see if they allow it. So I need to put a component list together of what I can afford, and most importantly be competitive, and have the range. So any advise would be good.

I found a motor that's 120hp and 260Nm and weighs just 40kg. But it's 120v and 760 amps. So if anybody knows the best way to power that for 30mins at full power, affordable and not too heavy. That would be good.

This was the motor I found.

http://www.evwest.com/catalog/product_info.php?products_id=469&osCsid=u4qt21euiqt3gfa6j9nkehda93
 

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I'm hoping to get a plan together of what I would roughly build, and then go to NASA before construction to see if they allow it.
That makes sense to me.

I found a motor that's 120hp and 260Nm and weighs just 40kg.
...
This was the motor I found.

http://www.evwest.com/catalog/product_info.php?products_id=469&osCsid=u4qt21euiqt3gfa6j9nkehda93
The Hyper9 is new, so there's little experience with it, but it does seem promising for those not wanting to run the higher voltage of modern production electric vehicles.

But it's 120v and 760 amps. So if anybody knows the best way to power that for 30mins at full power, affordable and not too heavy. That would be good.
In the worst case, that's 91 kW. If you really needed all of that all of the time for 30 minutes, you would need a 46 kWh (usable capacity) battery. That's bigger than most production electric cars, other than Teslas. With any luck you can use an entire Chevrolet Volt or Nissan Leaf battery, reconfigured for one-third of the voltage.
 

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If I were going to mount the engine side-on, like a fwd configuration, I would probably use an autograss drivebox. This is just a single geared box that allows motorbike engines to convert from a cog, to driveshafts. You can alter the gearing inside them to suit the set up, or even the track length.
That seems like a good solution, if you can get the right reduction ratio. In a motorcycle-engine application, they're using the motorcycle gearbox as well, so there would be little additional reduction in this box. In a quick search, I'm seeing about 3:1 for boxes intended for motorcycle drivetrains, which is not nearly enough; with 3.33:1 gearing, 8,000 rpm maximum motor speed, and 24" tall tires, you're geared for 270 km/h! I you gear lower, you get more torque to the wheels at low speeds. At high motor speeds, the motor is power-limited so the gearing doesn't matter much.

Some of the boxes for motorcycle drivetrains incorporate a reverse, which you won't need.

My guess is that at least some of these boxes don't have a differential, and that differentials are not used in most of these cars.

Do you have a specific gearbox that you're considering?
 

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Discussion Starter #10
There are a few autograss driveboxs for motorbike engines available
http://berrisford.co.uk
http://www.extremeracecars.co.uk/site/ (Driveline gearboxes) are just a couple. Berrisford do geared boxes but they aren't on his website, only his chaindrive ones are on there. Reverse gear and diffs aren't needed.

With my latest hours upon hours of research, I'm thinking that 10minutes of racing time is my aim. This won't allow for any re-runs but as it would be a prototype, this is one of the many risks I'm going to have to just roll the dice on. So my latest idea is to use the warp 11 motor. Which apparently gives 32hp at 144v, and 283Nm at 450 amps. The top class 5s are running around 180bhp, and I'm unsure of the torque figures. So we are going to be down on these cars, but I'm not delusional, I'm expecting to be at the back of the pack being the first to try this, and then try to improve from there.

So now I am thinking of powering it with Nissan Leaf modules. I'm thinking using 20 of the 7.6v 66Ah modules to make a combined power of 152v @ 66Ah.

Driving at a hard pace (50% full beans, and 50% 1/2 beans) I'm hoping to get towards 10 minutes of driving from this. If anyone has any input on this, please jump in and feel free to call me an idiot. I'm unsure I can drag that sort of power, that quickly from it. With a battery weight of roughly 130kg and a motor weight of 110kg. I'm confident of getting the entire kerb weight of around 700kg. That would be 150-200kg more than a competitive class 5.

My maths also say I need a maximum of roughly 1000rmp wheel speed so will need a dropergear of 6/1(ish) I could probably find a RWD axle with that ratio. So maybe bolting the motor directly to that might be a good idea after all.

So we will be down on power, and carry more weight, be at the back, but be the first one.
 

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Suggestions

(1) - Volt batteries seem to be set up more for high power than Leaf

(2) - speeds and voltage
I'm using an 11 inch Hitachi motor - about the same as your Warp 11
You need high voltage to push a lot of amps at high rpm
I'm running 215/45/17 tyres and a 4:1 diff - and I'm using 340v
When I had 130v I was voltage limited to 100 kph

You don't want 6000rpm with an 11 inch - aim for about 4000rpm
With only 152v you will have almost no current at 6000rpm

Using my car as a basis if you use most of a Volt pack you should easily beat your weight target
Mine is street legal two seater - heavily built - and 805kg
I'm using over twice as much battery as you intend - and I don't think my batteries are much heavier than 130kg

I could get down to 180 hp easily - that's what I use on the road
On the track I have nearer to 500 hp available

You should be a little bit heavier but have MORE power available
 

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Discussion Starter #12
Unfortunately the Volt isn't available in the UK. But going on your numbers, the leaf could still be a good battery donor. I was planning on using 20 of the 48 modules that the leaf battery pack carries. It wouldn't be any problem to double the voltage by putting 40 in. But 260kg of battery would be a major disadvantage. But if I could get more power than hoped like you are suggesting, that disadvantage obviously shrinks. I'm surprised of your numbers. Especially as the leaf battery is 24kwa compared to the volts 17. What other hardware are you using?
 

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Hi

http://hybridautocenter.com/HAC4/index.php?option=com_hikashop&ctrl=product&task=show&cid=91&name=58ah-nissan-leaf-battery-module&Itemid=605

This has Leaf modules as 3.8 Kg each - so 40 would be 152 Kg - and 336 volts

I'm overstressing the battery a lot - but it hasn't melted so far

The manufacturer is thinking 200,000 miles and no failures - if you are racing you stretch the envelope!

The official peak current is 540 Amps - if you use 1200 amps then you will exceed this - but only for a tiny amount of time

With a DC motor - motor voltage x motor current = battery voltage x battery current

At low rpms it only takes a few volts to get your motor current

Motor - 34v x 1200A = Battery 340v x 120A
Then as the revs go up you get back EMF - roughly proportional to rpm x current
With an 11 inch motor at about 3000 rpm you will need the whole 300v (it will sag) to drive 1200 amps
Above that even at 100% you would be able to maintain your current and it will start to drop


So in a drag race your battery will see
Battery - - - Motor
120 amps - 1200 amps
240 amps - 1200 amps-
360 amps - 1200 amps
480 amps - 1200 amps
600 amps - 1200 amps
720 amps - 1200 amps
840 amps - 1200 amps
960 amps - 1200 amps
1080 amps - 1200 amps
1200 amps - 1200 amps
1000 amps - 1000 amps
800 amps - 800 amps
600 amps - 600 amps


If you are thinking about the complete Volt/Leaf battery there is a lot of armour and general junk that you don't need
 

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(1) - Volt batteries seem to be set up more for high power than Leaf
That makes sense. Plug-in hybrids such as the Volt must carry a smaller battery than a battery-electric car, since they are carrying around an engine and everything to support it (about 16 kWh for a Volt versus 24 kWh for a Leaf). At the same time, the plug-in hybrid needs just as much battery power output as the battery-electric, for the same performance when the engine is not running. The net effect is that the plug-in hybrid gets cells with a higher power density, likely at the expense of energy density.
 

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Discussion Starter #16
Ok then guys, you know a lot more than I do. How would you go about it? What battery, motor and other hardware would you use? Like I said previously. I'm a pretty handy fabricator and mechanic. But I've never got my head into EVs. Do you know of any kind of "EVs for dummies" websites or videos you could recommend?
 

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For what you are doing have a look at my Device

Motor - DC is cheap cheerful and powerful - you need an 11 inch motor about 100 Kg
I paid $100 for mine - you need to advance the brushes

You can buy a Warp 11 - which is the same thing but nice and new

Batteries
Leaf - or Volt/Ampera - or even Tesla - see what you can find

Controller

I'm using a Paul & Sabrina - 1400 Amp - 360v monster

http://pandspowerelectronics.com/

You may have to contact Paul to get one
Otherwise you may be able to get a Soliton 1 - or a Zilla

I'm using a Subaru Legacy Diff - 4.1:1 and it comes with an LSD

Charger - I'm using a BRUSA - there is guy in Europe selling them cheap - Isle of White (I think)

Instruments - I won't recommend mine as they are dubious!
 
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