# Planning 2002 BMW (e46) 330Ci conversion - track car



## davidkillion (Sep 4, 2016)

I have experience working on cars, but have never done an EV conversion. I also have 12v electrical knowledge from my days building car stereo systems.

I am in possession of a salvage title (repaired) E46 BMW that I was going to build into a Spec E46 race car but have recently decided against it. It is too nice to completely gut the interior, and ... as my wife keeps reminding me ... I already have a race car. She's right, as usual. However, what I don't have anymore is a drive-to-track car; something that is street legal as well as capable in the twisties.

So, why not take this nice E46 (which I drive every day to work - 80 miles round trip) and convert it into an EV that would also kick butt on the track? Then I can get my deposit back on that Tesla Model 3.

Let's be clear, I'm not here to save the planet. I think EV is cool and I want to pioneer the use of EVs as track cars. Internal Combustion engines are inherently complicated (mechanically) and prone to 'blowing up' especially when tuned; an electric motor and controller are far easier to work on/replace. Further, if there is a failure, it doesn't spew oil and coolant all over the track. 

Goals for this build:

160 mile range
Drive-to-Track car.
I want it to be able to turn impressive lap times (2:00 at Thunderhill, 1:45 at Laguna Seca, etc). I do these times in a 2600lb race car with a 250HP gas engine; I see no reason why an electric car couldn't do this.
It is a clean car, I want this to be a spotless build. Impeccable wiring.
I already have all the suspension upgrades (coilovers, bushings, ball joints, etc). Still need to reduce weight as much as possible, but keep it livable.
1/2 cage with 6pt harnesses and racing seats.
Retain full A/C, heat and other creature features
Swapable batteries so I can drive to the track, do track sessions, and then drive home afterwards. I am willing to tow a tire trailer with extra banks of batteries if that is what it takes.
Budget: $30k (donor, suspension and diff are already purchased)

I get that this is an ambitious build, especially since I have never embarked on such a task. I will need help from those that have done this, and since I have yet to see DIY EV conversion at the track, I don't have a network to consult.

I have a lot of questions such as:

Is the E46 an acceptable donor car to achieve my goals? I sure hope so because I'm already invested in making it handle great.
It is an OBD2 car and I want to preserve things such as ABS, power windows, etc - but ditch things like the airbags and petrol engine. What kind of challenges does this present?
How do I chose a motor and controller? Since this is a track car, I don't want it to be a slouch - but it can't be too outrageous either because of battery life.
Is there a conversion kit for an e46 BMW? 
Assuming there isn't a conversion kit, where can I get any necessary fab work done in the Bay Area of California?
I just had a 3.45 OS Giken LSD built - is this gear ratio ok?
Do I use the ZF 5-speed transmission? If not, what is the suggestion? 
How do I preserve A/C & heat? Maybe a Vintage Air solution?

... honestly, I don't even know where to start. Thankfully, I'm not in a rush --- but I am excited about the project.


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## Kevin Sharpe (Jul 4, 2011)

Can I suggest you take a look at Damien's (DIY username jackbauer) website?

http://www.evbmw.com

You might also want to give EV West a call given you're on the west coast;

https://www.youtube.com/watch?v=6vDIAGSjr-8


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## madderscience (Jun 28, 2008)

A 160 mile range, performance build for $30k is challenging. I'd keep the deposit on the Model 3 if I were you. 

If you did want to move forward with the BMW, then some specs:

Driven "normally" and with street tires, that car would probably need about 250wh/mile to maintain 60mph straight and level. So for a 160 mile range, you are going to need a 50kwh battery pack (with usual 20% margin for max DOD). That's basically two 100% healthy nissan leaf packs (48kwh) and about 800lbs of weight, or the battery out of a Tesla Model S 40 or 60. Doable these days, and might not totally break the bank, but you are probably going to have to lose most of the trunk space and back seat.

Making the battery swappable would be fun in its own right, that will add weight, complexity, and extra failure points (e.g. all the plugs and connectors).

For motor, best bet is probably a dual stack Remy HVH250 and appropraite controller. That setup is available from a couple of performance oriented EV parts resellers. Not cheap, but YGWYPF. 

Not mentioned but vitally important of course is an appropriate charger, BMS, and safe battery mounting and enclosures.

You can absolutely build a very good conversion for $30K, but for what you are describing I'd probably be expecting more like $40-50K, especially if you want to have show quality finishes, meaning DIY-grade assembly techniques (which can be totally safe and functional, but maybe not as pretty) are out.

Good Luck.


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## davidkillion (Sep 4, 2016)

madderscience said:


> A 160 mile range, performance build for $30k is challenging. I'd keep the deposit on the Model 3 if I were you.
> 
> If you did want to move forward with the BMW, then some specs:
> 
> ...


This is awesome feedback; exactly what I need to hear. The basis for the 160 mile range was the one-way trip from my house to Thunderhill Raceway. That might not be feasible given your calculations - definitely not worth the $10-20k premium. My round-trip to work is only 75 miles, so maybe this would be a better benchmark. Then I would plan to tow it to the tracks that are further away.

I'm honestly questioning my choice in vehicles. I chose the BMW because I have it in my hot little hands and it already has a quite capable track suspension setup. But a) it isn't the lightest car, b) there is nothing wrong with the current power plant and c) I'm using it to commute now --- it would have to be taken out of commission for a [long] while to do the conversion.

I might be better off choosing another track capable car such as a Miata, Elise, 914 or 911. The Porsche donor cars could get expensive, but EVWest has conversion kits to get me started. Presumably using a conversion kit would save me a whole lot of frustration given the learning curve of my first build. 

Thanks again!


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## Hollie Maea (Dec 9, 2009)

Keep in mind that most EVWest kits use relatively low performance air cooled motors. Might be a limiting factor with the kind of sustained performance you are looking for.


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## davidkillion (Sep 4, 2016)

Hollie Maea said:


> Keep in mind that most EVWest kits use relatively low performance air cooled motors. Might be a limiting factor with the kind of sustained performance you are looking for.


Fair enough. But am I correct in assuming cars that have conversion kits will generally require less fabrication even if some of the components are upgraded? I guess that would be a question for EVWest, but if anyone has experience that would help.


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