# Porsche 914 performance newb questions



## TEV (Nov 25, 2011)

Welcome.

You can start your research here :

http://www.diyelectriccar.com/garage/cars

and here:

http://www.evalbum.com/type/PORS


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## Ziggythewiz (May 16, 2010)

Cglover said:


> Things Im really confused about:
> -Does your voltage and current ratting come only from batteries? People say 150-300V and 400-1000A from what I have seen. Does the controller effect this or not?
> -Are there motors that are typically "performance" motor?
> -Do controllers act as a battery controller or are they two separate things?


Your limits come from all your components, the battery, controller, and motor being the main ones. Whichever is the weakest link will limit you.

Your $10k will cover your 60 mile battery pack pretty well, but won't leave much for anything else. If you're good with electronics you can look into the Open ReVolt project to build your own controller cheaper, and maybe charger as well.

Many people refurbish forklift motors to save $$$ there.


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## Yabert (Feb 7, 2010)

Easy way:

Motor: 2k$ (Warp 9, Impulse 9, Kostov 11 or K9 HV)
Controller: 3k$ (Soliton1, Zilla)
Battery: 6k$ (Calb CA)
Rest of parts: 2-3k$

Hard way:

Motor: < 500$, used forklift motor
Controller: < 1000$, 1000A Open ReVolt
Battery: < 5000$, Turnigy nano-tech or similar Lipo
Rest of part: <1000$


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## onegreenev (May 18, 2012)

> Motor: 2k$ (Warp 9, Impulse 9, Kostov 11 or K9 HV)
> Controller: 3k$ (Soliton1, Zilla)
> Battery: 6k$ (Calb CA)
> Rest of parts: 2-3k$


Slight Revision: 

Controller: Synkromotive $1600


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## Cglover (Feb 28, 2013)

Thank you guys, very helpful threads. Ill probably look at lowering my range to save some money on batteries. I like the look of the warp9 motor, how well does it hold up to being dogged on? I assume that depends on volts and amps being run, but lets just say I'm running what's it's rated for, nothing crazy.


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## Yabert (Feb 7, 2010)

Cglover said:


> Ill probably look at lowering my range to save some money on batteries.


Not really! Because save some money on batteries = less power.

The Warp 9 (at 170v and 1000A) can output around 270 lbs-ft of torque and 170 hp peak.
But again, the battery will be the weakest link in your case (as many others!!!).


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## Cglover (Feb 28, 2013)

Oh ok I think I see how it works. So if I'm looking at 40amp hour batteries at 3.2v each I would need about 60 of them? 

For example: http://manzanitamicro.com/products?...age.tpl&product_id=77&category_id=30&vmcchk=1

I just want to know if I'm thinking about this correctly.


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## Yabert (Feb 7, 2010)

Yea, 192v 40Ah nominal (7.68 Kwh) can be a good battery pack.
But the tricks here is the cells voltage will sag under load. So that kind of battery pack can't securely supply more than 72 Kw of power (rough calcul).

A more appropriate battery pack, can be 75 cells 60Ah (240v nominal (14.4 Kwh)) or 48 cells 100Ah (154v nominal (15.4 Kwh)) who can probably supply over 135 Kw of power.


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## Cglover (Feb 28, 2013)

Ok cool. There peak amp out will essenchly determine the motor power correct? The pack would need to be capable of about 800A burst, correct? Those cells say they are good for about 400 so would I need to double up on them to get close to 1k amps? I guess this goes for anything for 40amp hour to 100amp hour.


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## Cglover (Feb 28, 2013)

Never mind I should have read the specs first. The 100 amp h cells are much better. You think 48 would be enough?


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## Yabert (Feb 7, 2010)

Enough for 0-60 mph in 7-8 sec. Right?

The answer can be yes or no, that depend of the final weight of your car and the motor and controller you will choose.


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## dtbaker (Jan 5, 2008)

Cglover said:


> Never mind I should have read the specs first. The 100 amp h cells are much better. You think 48 would be enough?


48 cells (156v nominal) will get you more power for sure, but not much more range as the efficiency of the motor goes down at higher voltages and weight goes up.

in a 914, 156v x 100ah would be overkill in my view. If you build with 144v (45 cells) you'll save a little cost, save a little weight, better motor efficiency, save a little space and have PLENTY for rocking performance. I would suggest you pony up for the 'new' gray CALBs if you intend to tromp on them, and go no smaller than 100ah if you intend to get a 600 or 1000 max amp controller.

Warp9 will be plenty, and consider that a Soliton Jr. (600 amp max) cost the same as a Zilla 1000amp, you have to make a decision..... The Warp 9 can handle the amps, for a few seconds, but that's all you need to get up to speed!


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## PThompson509 (Jul 9, 2009)

Aside from the motor and controller - you REALLY need to make sure that all of the rust is taken care of. The 914s have a nasty tendency to rust on the very important longitudinal bars. I suggest you find a local 914 expert and have them look it over. It could be that the car is toast and not convertable, much less safe to drive.

I got VERY lucky with mine, but a good friend (also has a 914) had to buy a second as the first was too rusted to use.

Oh, and get all the 12v issues resolved before doing the conversion - this will save you time and anguish later (as I discovered).

Cheers! Peter


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## Yabert (Feb 7, 2010)

Cglover said:


> *What I really want to focus on is power!* The 914 is slow stock so I want to correct that, looking for around 7-8s 0-60 time, doesn't sounds unreasonable to me.





dtbaker said:


> If you build with 144v (45 cells)...


So, why do you suggest to drop the peak power by 6%?



> Warp9 will be plenty, and consider that a Soliton Jr. (600 amp max)


So, why do you suggest to drop the peak power by 40%???????


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## dtbaker (Jan 5, 2008)

Yabert said:


> So, why do you suggest to drop the peak power by 6%?


space, weight, efficiency of motor increases at lower voltage. I think performance and range would be virtually unchanged and cost savings and availability of components easier at 144v nominal than 156v nominal.



Yabert said:


> So, why do you suggest to drop the peak power by 40%???????


from 1000amp to 600 you mean.... well, what I'm finding in the Miata is that extra power is almost wasted in most conditions because when I'm hitting over 600amps, the rear wheels are breaking loose if I launch in 2nd gear and because I am not being very kind to my 130ah cells . I have the older CALBs and feel a little bad for the times I take them over 5C, but if the new ones really can take 10C, then going for 1000amps from the 100ah cells takes that limitation off the table. I'm suggesting the Lotus philosophy in that more power is not always better when you can cut weight, cost, and still get rock star performance.

so, the decision of Soliton Jr. (600amp) versus Zilla (1000 amp) becomes a preference thing now that Zilla are available again since they cost about the same. They are both highly programmable, both accept either pot or HEPI throttle, both have fluid cooling built-in... differences in method of setting parameters (serial versus html), built-in contactor/pre-charge or not, and the need for external inductor w/ Soliton.


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## Yabert (Feb 7, 2010)

dtbaker said:


> ....weight, efficiency of motor increases at lower voltage.


Humm! Loose 6% of power to don't add 1% of weight...

Well, despite 120v,144v, 156v or 200v battery pack, typical DC motor (warp9 as example) don't need more than 100v to push a ''light'' car in most condition (30-70 mph as example). Higher voltage is only supply to the motor during acceleration or during situation requiring higher power (slope, strong wind).


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## dtbaker (Jan 5, 2008)

Yabert said:


> Humm! Loose 6% of power to don't add 1% of weight...
> 
> Well, despite 120v,144v, 156v or 200v battery pack, typical DC motor (warp9 as example) don't need more than 100v to push a ''light'' car in most condition (30-70 mph as example). Higher voltage is only supply to the motor during acceleration or during situation requiring higher power (slope, strong wind).



I'm planning to make some performance runs with the Miata, setting the Zilla to limit at various amp and voltage limits to compare apples to apples... just haven't gotten to it, and not quite sure how to accurately record the time/speed points yet. I'm thinking I need either a passenger good with a stopwatch to catch the times at each 10mph, or perhaps a way to video the speedo and extract from the frame times in video editor.

as a rough measure of kWhr fro the wall when re-charging I can only say that the 156v nominal /warp9" is far less efficient with regard to average miles/kWhr than the 120v / ADC8". The Miata does weigh more than the Swift, which may be part of it, but not all of it as it is very hard to keep my foot off the floor in the Miata.


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## Ziggythewiz (May 16, 2010)

dtbaker said:


> I'm thinking I need either a passenger good with a stopwatch to catch the times at each 10mph, or perhaps a way to video the speedo and extract from the frame times in video editor.


A passenger couldn't get more than 2 good readings per run, plus that's a lot of dead weight 

If you don't have a video camera, any laptop with a webcam can do for temp duty.

Does the Zilla do logs like the Solitons? If you have a tach the logs would probably be the most accurate record.


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## GerhardRP (Nov 17, 2009)

dtbaker said:


> I'm planning to make some performance runs with the Miata, setting the Zilla to limit at various amp and voltage limits to compare apples to apples... just haven't gotten to it, and not quite sure how to accurately record the time/speed points yet. <snip>


Have you tried hooking up the Zilla monitoring stream to a laptop?


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