# Sport Car/Luxury Sedan Conversion Thread



## rwaudio (May 22, 2008)

Since you have the CAD capabilities then I would say the donor is the car that you REALLY REALLY want, you don't need to rely on off the shelf parts for coupler/adapter plate etc. 

So what kind of car do YOU want? Any older cars that you've lusted after since you were a kid? I always wanted a slant nose 911 but I couldn't swing the donor plus a conversion so I went with a 944 instead but I'm still happy!


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## ctown30 (Dec 2, 2011)

Right, I'm not so much worried as to what cars are more adaptable to conversion, but rather what cars from peoples experience have less drag, curb weight, etc and would get better range/performance.

As far as MY choices:
Sports Car - Lotus Elise would be first for sure, but the cost of that plus conversion would probably exceed my budget.

Luxury Sedan - I like the Newer ( 2003-12) BMW 3 series, and like the newer (2003-12) Audi A4

But if there is any car out there that is similar in style that has less drag/ would perform better (better range, acceleration, etc) I would prefer that. So any insight there would be greatly appreciated.


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## Salty9 (Jul 13, 2009)

Check Thumper's LoCost build. http://www.diyelectriccar.com/forums/showthread.php?t=65056&highlight=thumper


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## gor (Nov 25, 2009)

factory5 bodies, replicas, kit cars ... check evtv
like http://www.evmania.com/blog/


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## ctown30 (Dec 2, 2011)

Gor thanks for the input. I know OF kit cars but don't know much about them. Will definitely look into it as this is going to be a fully custom car anyways. Love to have an electric ferrari lol


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## ctown30 (Dec 2, 2011)

Well I have had a chance to look at cars more, and I think I have decided on the donor cars. For the sports car, I got looking into the kit cars and have become obsessed with the Ferrari F430 Scuderia kit made by DNA Autoworks, so much that if I don't end up doing an EV conversion this is still definitely something I would like to do . It is based off of a Mercury Cougar (so really that is my donor car). This will be my high budget (dream) design

For the sedan (more practical dsign), I think I am going to go with a BMW 325i, somewhere around a 2003 as they can be had used for a reasonable price and will be lower when it comes time to actually building the car.

So now on to question 2: AC or DC for these vehicles?
Still looking to hit earlier stated mileage and 0-60 speeds. Probably a little closer to to 4 seconds though for the sports car since it is going to be a Ferrari (Fauxrarri) lol.

Thanks again for everyone's help!


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## rwaudio (May 22, 2008)

ctown30 said:


> Well I have had a chance to look at cars more, and I think I have decided on the donor cars. For the sports car, I got looking into the kit cars and have become obsessed with the Ferrari F430 Scuderia kit made by DNA Autoworks, so much that if I don't end up doing an EV conversion this is still definitely something I would like to do . It is based off of a Mercury Cougar (so really that is my donor car). This will be my high budget (dream) design
> 
> For the sedan (more practical dsign), I think I am going to go with a BMW 325i, somewhere around a 2003 as they can be had used for a reasonable price and will be lower when it comes time to actually building the car.
> 
> ...


Nice choices in donors, hard to go wrong with a 3 series, and the Fauxrarri would just be cool in general.

There aren't too many AC systems available to the average joe other than the AC50/Curtis stuff from HPEV which just isn't going to give you the performance you want without using a few of them. A simple DC setup should get you in the ball park using a warp 11HV, and 1000A or higher controller and a 300v pack.

In short I would say AC is the way to go, but cost and availability make DC the only real option without getting very creative with multiple motors.


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## ctown30 (Dec 2, 2011)

Rwaudio, thanks for the reply! Yeah I was kind of thinking on the same lines as you are. I would like to go the AC route with regen and everything but for right now it seems the most practicle/best available systems right now are DC. So I feel like that is what I am going to go with for now. If any other members have any other suggestions though please feel free to let me know. 

So I am going to move on to question 3: what size motor? (But if anyone has any suggestions about any of the previous questions, please feel free to comment!)
As far as size wise I was thinking along the lines of a Warp 11. Would this be good for both vehicles, or should a smaller motor such as a Warp 9 be used with the BMW? Or should I step up to a Warp 11 HV for the fauxrarri ?


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## gor (Nov 25, 2009)

Ferrari - good, but don't forget about Lambo! Pontiacs Fieros been good donors for Lambo kits

just in case - for all info and ideas to be in one thread:

- hotrods, vintage cars? slight pt-cruiser mod?









- remember Fisker?(Karma) - for long time they been making small series production - on base of new good cars - super cars (some design companies doing it too)
guy from Baltic does it himself, easy way, but taking to extreme
(foam & bondo, no fibeglas)
http://www.madmechanics.com/forum/t...74-guy-modifies-cars-pu-foam-see-results.html

- or you can start with something smaller first, like that little one


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## Joey (Oct 12, 2007)

ctown30 said:


> So I am going to move on to question 3: what size motor?
> 
> As far as size wise I was thinking along the lines of a Warp 11. Would this be good for both vehicles, or should a smaller motor such as a Warp 9 be used with the BMW? Or should I step up to a Warp 11 HV for the fauxrarri ?


Power comes from the batteries. The motor converts electrical into mechanical energy. Figure out how much battery power you need to achieve your performance goals and then select a motor that can handle the load. A bigger motor will not help if the batteries are not able to supply the power.

I like the direction you are heading with your project. Look around for projects with similar goals to get an idea of how much battery you will need.


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## Joey (Oct 12, 2007)

ctown30 said:


> Hello everyone, I am new to the scene of EV conversions and am looking to start planning a future build. I am currently finishing up getting my Mechanical Engineering degree and therefore have no money lol. That's why I am looking to start planning out an EV vehicle now, so when I do have money I can start building right away.


That's how it went down for me, too. I just got my donor vehicle yesterday. Take your time, keep saving, and do it right. Best of luck.


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## charliehorse55 (Sep 23, 2011)

I have been researching into creating a luxury sedan much like yours. I chose the 328i. It is a great choice for a donor car. It has a very low coefficient of drag but can still support a pretty large gross weight. 

Additionally, it already has these awesome features:
-built in electric power steering
-built in electric manual shifting 
-rubber vibration separation between drive shaft and transmission
-electric throttle - easy to hook up to a controller
-electric air conditioning - no need to even touch the stock system
-EVERYTHING is on CAN bus. I mean everything. This makes it really easy to capture data into your main computer. 

I plan to use an AC motor, specifically the AFM-140 from EVO-Electric. I am going to remove the clutch and bolt the motor directly to the transmission. With the BMW electrically operated transmission, the car can either be driven as an automatic or a manual. When in automatic mode, when the computer detects that a gear shift is necessary, it will automatically put the motor in neutral, rapidly (less than 200ms) synchronize the motor speed and shift back into gear. If you want to drive it manually, it will perform the same operations but on the will of the operator pressing buttons on the steering wheel. 

*The entire shifting process will take less than 0.3s to complete. *

http://en.wikipedia.org/wiki/Electrohydraulic_manual_transmission


To get that range, I am using the same batteries that Tesla uses. I found a supplier from China to supply NCR18650s that are 2.9 Ah / 3.6v cells. At 240 Wh/kg, they are the only battery capable of that long range you wanted. 

Add me on skype, I have a LOT of information compiled about this project. 

evantandersen


--Evan


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## ctown30 (Dec 2, 2011)

Thanks everyone for your input. Gor, as far as donors I think I am pretty set on the Ferrari kit car and the 325i (but will definately look into the 328i as Evan is suggesting), but thanks for your input as it may be beneficial to others following this thread.

Joey, I understand that alot of the motor selection depends on the batteries. I guess I was more or less trying to see what size motor would produce enough torque, hp, rpm's, etc to get the 0-60 times and still be able to push the cars into the 80 mph area, given the proper battery pack. If the Warp 9 can handle all the weight of the car and still get up to speed quick then I would probably use it since the cost is lower. But thanks for your input and maybe I should talk about batteries before the motor, although now that the donors have been (mostly) decided on it seems that its hard not to talk about all the different electric components at the same time

Evan, Thanks for the great info and suggestions. I will definitely look at the 328i, it sounds like a great donor for a conversion. It is great that a lot of the features are electric controlled (steering, air conditioning, etc). I'm curious as to how all the electrical systems will link together and work though. I assume you are going to keep the car's current ECU and use it to control steering, ac, etc but I'm just curious as to how the tranny will work with the motor and what will control it (current ECU)? Also, isn't the clutch still needed?

As far as your motor is concerned I will take a look at it, but I am just concerned with AC about not getting enough power due to a very limited range in motor and controller selection.

I am really excited to hear you are planning an 18650 cell battery for your vehicle though, as that is what I have been hoping to use from the beginning. I have found a few suppliers in china that can supply the NCR18650A, which is the 3.1 Ah cell. So I am curious to hear more about what you have planned for your battery pack design.

I appreciate your help, and will probably be contacting you through skype but would really like to keep as much conversation as we can here on the forums so other members who are following can be involved in the conversation, and learn along with us .

Thanks again everyone for your comments, and keep the coming . I am really excited about this and really wish I had the funds to start now, but I know careful planning now will pay off a lot later on.


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## charliehorse55 (Sep 23, 2011)

*Clutch*
The usual purpose of a clutch is two-fold - both to synchronize the engine and transmission speed during shifting, and to absorb impulse generated by bumps on the road. 

By using a computer to automatically synchronize the motor speed, the clutch is no longer needed to shift gears. The transmission will shift into neutral, and then a computer will command the motor to apply to maximum torque. This will VERY quickly change the speed of the motor and synchronize it with the speed of the transmission. The transmission can now shift into the next gear very easily. 

The second function of the clutch is to absorb impulse from bumps in the road. When you hit a bump, an impulse is sent down the drive train. With a regular ICE motor, this impulse will fight the incredibly large moment of inertia in the engine. The result is a snapped crank shaft. BMW installs a small piece of shock absorbing (rubber perhaps?) material in between the differential and the transmission. This normally works in tandem with the clutch to reduce impulse. As an electric motor has many times less moment of inertia, an impulse is much less likely to damage the motor shaft. Many people actually run clutchless without any form of shock absorber between the motor and the wheels without issue. Having the extra shock absorber installed as well makes sure that you won't have any issues with snapping drive lines. 

*Batteries*

Panasonic makes the only batteries that even viable for such long ranges. They have two cell types:

NCR18650 - 3.6v / 2.9 Ah - 44.0 grams - 237 Wh/kg
NCR18650A - 3.6v / 3.1 Ah - 44.6 grams - 250 Wh/kg

Due to these batteries low discharge rates (3C, 5C absolute MAX) you will need a pack size of at least 50kWh to get good performance. Using a value of 200Wh/kg (to include the battery boxes and structure for these 18650s) that gives a weight of 250kg. If you go with this pack size, at 80% DOD you have 135 mile range at 300 Wh/mile

If you go with the heaviest pack you can manage (about 400kg) you can get a 80kWh pack which gives you a 215 mile range at 300 Wh/mile. 

The cheapest price I found is:

2.9 Ah - $2.85 /cell
3.1 Ah - $3.90 /cell

Which, for a 80kWH pack means:

2.9 Ah - $21k
3.1 Ah - $28k


*Motors*

The AFM-140 is probably your best bet if you want to go AC. It has 220 HP and only weighs 40kg. Together with the Tritium 200 controller the entire powertrain will only weigh 48kg. As the original ICE power train was about 300-400kg, (motor, clutch, fuel tank/lines, exhaust system the weight saved here can be used for extra batteries.

Here are it's specifications:

550 Nm Torque
165 kW Peak Power
85kW Sustained

With the 325/8i you will be looking at a curb weight of around 1400-1500kg. With a 165kW motor you will have a 0-60 time (neglecting shifting) of 4.1 seconds!

*Heating/Cooling*

I am Canadian. Temperatures regularly go below -10C during the winter, and can hit -30C. (14 to -22 in F). I need to make sure that both the batteries and the occupants of the vehicle are kept warm. 

I have two options for heat:

a) Use theromelectric heating - 1.5x the amount of input power as heat
b) Buy a air source heat pump unit - 5x input power as heat

Theromoelectric heaters are small, light and guaranteed to always work. Unfortunately, they don't produce a lot of heat. In conjunction with heated seats it might work out okay, but I'm going to be pulling at least 5kW constantly just to keep warm. 

With an air source heat pump I would be pulling 1.5kW to receive the same 7.5kW of heat as the purely electronic. The disadvantage is that this unit weighs about 50kg. It has the capability to also do air conditioning, so I would be able to remove the weight of the AC unit to compensate. Additionally, it only works down to -25C so on an extremely cold day I wouldn't get any heat. 

I can compare the two solutions by assuming that I will lose the weight of the If I assume a total added weight of 40kg for the heat pump, I get 8 kWh of lost battery size. 8 kWh/ 3.5 kW = 2.2 hours. Thus, on trips longer than 2.2 hours it makes more sense to use a heat pump, and on shorter trips it makes more sense to use the thermoelectric effect. In the summer, the added battery capacity directly translates into more range. 

*Charging*

A J1772 Standard plug will be installed into the fuel receptacle of the vehicle. The vehicle will support level 1 and 2 charging only, utilizing on onboard smart charger. A 15kW, water cooled charger will be used, capable of fully charging the vehicles battery in just over 4 hours. 



I'll post more later, I still have much, much more to post.


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## ctown30 (Dec 2, 2011)

Wow Evan, that's a heck of a post. Sounds like somebody is going to save me lots of time and research . I can't wait to hear the rest!

I am still a little confused however at how the transmission is automatically shifted, and/or (electrically) manually shifted? Because the original ECU of the car will have no idea what rpm the electric motor is at, and therefore could not know what to match the gear speed to when shifting? Also, how would it know when to shift gears as well? Or, is all this going to be controlled by a new custom main computer communicating over CAN? Sorry I know these are probably newbie questions and could probably be answered with a better understanding of transmissions.

But like I said I look forward to hearing more about your build. You planning on starting anytime soon?


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## drgrieve (Apr 14, 2011)

I've looked at the 328ci / 328i. They use pulleys to run the power steering from the pictures I've looked at. I don't think BMW started using electric power assist in 2007 from what I gather.

Interesting ideas using the steptronic - I've only looked at manuals - but if you've found a way to use the steptronic that would widen the donor pool a lot.

You should talk to valerun. He is putting together a kit for E46's. A solution for steptronic integration would be valuable to him I would think.


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## charliehorse55 (Sep 23, 2011)

ctown30 said:


> Wow Evan, that's a heck of a post. Sounds like somebody is going to save me lots of time and research . I can't wait to hear the rest!
> 
> I am still a little confused however at how the transmission is automatically shifted, and/or (electrically) manually shifted? Because the original ECU of the car will have no idea what rpm the electric motor is at, and therefore could not know what to match the gear speed to when shifting? Also, how would it know when to shift gears as well? Or, is all this going to be controlled by a new custom main computer communicating over CAN? Sorry I know these are probably newbie questions and could probably be answered with a better understanding of transmissions.
> 
> But like I said I look forward to hearing more about your build. You planning on starting anytime soon?


I plan on having an embedded linux computer to act as a central computer. It will control things such as shifting. 

I have not got to hands on yet, but I am pretty sure the steptronic works over CAN bus. I just have to capture the exact message sent from the ECU, and then get my replacement computer to send it out instead. 

The main computer will

a) Read the speed of the wheels
b) read the motor speed
c) calculate the difference
d) shift into neutral
e) command the motor to go to that speed
f) shift into correct gear


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## ctown30 (Dec 2, 2011)

Haha, I had a similar idea for my car to use a central computer to control as much as I could. I was planning on using a regular manual transmission as I didn't think that a computer could be used to control the automatic/steptronic transmission. But if it can that would be osm. Are you planning on using the computer to control anything else such as ABS, air bags, AC, etc based upon the cars other sensors and completely eliminate the main ECU?


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## charliehorse55 (Sep 23, 2011)

ctown30 said:


> Haha, I had a similar idea for my car to use a central computer to control as much as I could. I was planning on using a regular manual transmission as I didn't think that a computer could be used to control the automatic/steptronic transmission. But if it can that would be osm. Are you planning on using the computer to control anything else such as ABS, air bags, AC, etc based upon the cars other sensors and completely eliminate the main ECU?


ABS: Not sure how it's currently implemented
air bags: already controlled by an independent system if I'm not mistaken - I'd like to keep it this way.
AC: Probably. I figure I have to create a program to handle communication between my heating/cooling system and the stock interface. 

I plan to log ALL the data by capturing it from the CAN bus.


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