[justy344]

I have a 1980 mazda Rx7 that I would like to make in an electric sports car. Ideally I'd like to see a range of 50-100miles @ at least 55-70mph. It weighs 2385lb stock and only came with ~100hp 12A rotary to begin with. I'd also like to keep the stock 0-60 of 9 sec if not better. I've looked at the AC-50 motor kit (http://www.electricmotorsport.com/st...otors_ac50.php) and at these: http://www.houseofbatteries.com/documents/VL34-P.pdf for the batteries. Lets say at the moment that money isn't an issue (although it is but I'd like to know anyway) what am I looking at as far as amp hours for operation? and is the one motor enough? I'd be leaving in the stock 5speed. I honestly just wish I had enough money for a tesla roadster

[Bowser330]

Originally Posted by justy344

I have a 1980 mazda Rx7 that I would like to make in an electric sports car. Ideally I'd like to see a range of 50-100miles @ at least 55-70mph. It weighs 2385lb stock and only came with ~100hp 12A rotary to begin with. I'd also like to keep the stock 0-60 of 9 sec if not better. I've looked at the AC-50 motor kit (http://www.electricmotorsport.com/st...otors_ac50.php) and at these: http://www.houseofbatteries.com/documents/VL34-P.pdf for the batteries. Lets say at the moment that money isn't an issue (although it is but I'd like to know anyway) what am I looking at as far as amp hours for operation? and is the one motor enough? I'd be leaving in the stock 5speed. I honestly just wish I had enough money for a tesla roadster

we all wish we had enough to burn on a Tesla, and even though many of could afford one, it wouldn't be practical enough for our lives. Additionally a lot of the community is made up of real intellectuals, people from electronic and mechanical backgrounds that are looking for a challenge.

if you assume 300wh/mile, which is pretty standard, then 50-100 miles would require 15-30kwh pack. If you do end up using those SAFT cells (119wh) (which I feel the community would like to know how you are getting them and how much they cost) then you will need 252 cells to equal 30kwh of energy storage. They only weigh about 1kg which turns out a total pack weight of about 550lbs. Add another 100lbs for all the misc. battery trays and mounting equipment you will need with those loose cells, so 650lbs.

The AC50 is not going to give you 100hp its around 70hp with minimal voltage sag, however the peak torque of 100ftlbs+ is available form 0-rpm all the way up to ~4000rpm, so it should provide good acceleration, im not sure if it will meet your 0-60 in 9sec request, but with RWD and some wider tires for traction it may be possible. You may want to look at a DC system as well and do a comparison. You can get a Soliton1 (3000$) + Warp9 (1800$) for a little more than the AC50 package (4300$), the DC combo can peak ~250ftlbs & ~235hp

This is a setup I would recommend to you...

Motor = Warp9 (1800)
Controller = Soliton1 (3000)
Batteries = Calb CA 180AH (60 cells)

60 CALB CA 180AH cells:
192V @ nominal 3.2V
175V @ 2.9V (Voltage sag @ ~5C or 1000A)
12lbs each = 720lbs pack weight
35kwh total energy @300wh/mile = 117miles @ 100% dead or 93miles @ 80% (recommended not to exceed)
cost = 15K$

Major component cost = about 20K$

[skooler]

Originally Posted by justy344

I have a 1980 mazda Rx7 that I would like to make in an electric sports car. Ideally I'd like to see a range of 50-100miles @ at least 55-70mph. It weighs 2385lb stock and only came with ~100hp 12A rotary to begin with. I'd also like to keep the stock 0-60 of 9 sec if not better. I've looked at the AC-50 motor kit (http://www.electricmotorsport.com/st...otors_ac50.php) and at these: http://www.houseofbatteries.com/documents/VL34-P.pdf for the batteries. Lets say at the moment that money isn't an issue (although it is but I'd like to know anyway) what am I looking at as far as amp hours for operation? and is the one motor enough? I'd be leaving in the stock 5speed. I honestly just wish I had enough money for a tesla roadster

Hi Justy,

You won't reach your 0-60 goals with the ac50, AC motors and controllers are much more expensive per horsepower than there DC equivalents.

I would look at a soliton1 (400hp controller) and a warp 11hv or kostov 11 alpha.

As for batteries. Saft are great but likely very expensive and it would be quite difficult to put a pack together to go 100 miles.

Have a look into Sinopoly and CALB prismatic cells.

You will use about 300-350WH per mile in your RX7, looking atwhat similar sized cars get.(the mathematics says my RX8 should get 310 WHAT per mile for reference)

As an example, for 50 miles range, 300WH per mile multiplied by 50 (miles) is 15,000WH. As you can't run the cells completely flat divide this by the %dod (70-80% is a normal figure) 15,000 / 0.8 = 18750WH

Then do the above again at 350wh per mile

So call it 20-22kwh pack for 50 miles

You really want to run the controller at as higher voltage as possible (350v) this is normally 95-100 LiFePO4 cells.

Dividing your total pack size by the number of cells you want and at what voltage you will charge them to gives the AH size of each cell.

So 20kwh / 95 cells / 3.6volts per cell gives 58.48AH

Then round this figure up to the next available size of cell.

95 60AH cells would do you nicely.

As a sanity check, multiply the number of cells by the charge voltage and then by the AH capacity. You should get you pack size from earlier.

If you let us all know you budget,skill level etc members can suggest parts.

Hope this helps.

Cheers,

Mike

[dougingraham]

The RX-7 makes a for a good conversion project. I am pretty close to taking mine out for the first drive. I don't think the AC50 will get you to a 9 sec 0-60 time. The stock 12A at sea level has just over 100ft lbs of torque. At 1000 amps a Warp9 will do 277 ft lbs. I kept the clutch and transmission and I expect I will be limiting the current to the motor to prevent the clutch from slipping. With a WarP9 you should be able to do better than the stock 9 sec 0-60 time. If you dont put too many batteries on it probably between 6 and 7 seconds.

The biggest downside to converting one of the 1st Generation RX-7's is the age of the car. I thought my car was in pretty good condition but I found out both clutch slave and master cylinder needed to be replaced and the brakes needed lots of work. There is a weak spot inside the rear wheel wells where the car rusts out badly. I found it when I pulled out one of the storage boxes behind the seats. There is a reinforcement plate that apparently gets dirt and water under it and causes rusting issues. I removed the rust and glassed over the hole as my repair.

One issue is you cant use the flywheel from the 12A. It is counterbalanced and so will shake like mad if you try to use it. Fortunately you can get an aftermarket lightweight aluminum flywheel (12 lbs instead of 23) without the counterbalance. If you need a clutch you could also replace the clutch with a puck type and a pressure plate with more force. The centerforce types dont work for electrics since we have most of our torque at zero rpm. There are also racing options where you can get down to about 4 lbs for the flywheel and about 5 lbs for a multidisc clutch but this is worth about twice what the whole rest of the car is worth. So unless you are really well heeled is probably not a real option.

Here is a link to my photo album. I am still (always) behind on updating it.

https://picasaweb.google.com/1034409...CLXh6NrWmrOGQw