# Miata EV hit the road today



## dimitri (May 16, 2008)

Well, after 3 weeks of hard work, my Miata hit the road today. Let the count of electrical miles begin, I wish I could reset the odometer 

First impression is great, acceleration is about the same as original, it sits 1.5 inches lower with 1000 LB of lead. Breaks work well with electrical vacuum pump. Steering is tough without PS, either I will address it later or I will get better arm muscles 

Does anyone know of any electrical PS pump? I am not going to add a pulley to main motor, I hate to do that.

What is typical temperature of Curtis controller after a few miles of driving? Is it supposed to be hot to touch? I'd say about 120-130 F ? 

I drove around the neighborhood with 25 speed limit in 3rd gear, then on the street with 45 limit I shifted to 4th and got to 55-60 mph, with some room still at the pedal, with 2 adults in the car. If I was alone I could probably get to 70 mph, will find out later 

I will take it to weight station next week, to see how much weight it gained.

I am still waiting for ammeter to arrive , so I haven't installed instrumentation yet. Until then I will stay around the neighborhood.

I updated my garage page in case anyone wants to see pictures http://www.diyelectriccar.com/garage/cars/4


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## Vwbeamer (Jun 16, 2008)

nice 

How much those batteries weigh each?


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## joseph3354 (Apr 2, 2008)

congratulations!! wish you many years of enjoyable gas free driving!

as for a power steering pump,toyota mr2 uses an electric pump,so do the '07 and newer gm vehicles ,several models. check out this site.i have seen several different types available there ,used at reasonable prices. good luck! 

http://pamsauto.com/


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## RKM (Jun 9, 2008)

Congratulations!!

You made really great time. How many kwh in your pack and what DOD do you plan to run to? What range do you expect?

What would you do differently next time?

Thanks.

Rob


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## BHall (Aug 1, 2007)

Congratulations! 

Like I say after everybody else gets theirs on the road........I CAN'T wait till I am there with ya!

Brian


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## dimitri (May 16, 2008)

Thanks everyone for your kind words 

Each battery weighs 80 Lb , 155 AH , making a 144 V pack of 12 batteries total capacity of 22 kWh. I plan to stick to 80% DOD as recommended , with occasional 70% if need be. I hope to get 35-40 miles per charge at least. I just drove it for 18 miles today and voltage went from 154 at full charge to 143, so I should be OK with my range, considering batteries are new and still breaking in.

I will look into electric PS pumps, although even my wife drove it today and didn't complain much about steering, she did use both hands though 

I can't say what I would do different if I had to do it again, everything fit so perfectly like it was made for it. It was hard to put 12 batteries in, I tried couple of configurations unsuccessfully , had to redo it until found perfect fit for all 12. These batteries are larger than they look 

I love the humming of the motor and Curtis whine is not even an issue, I can't believe I was so worried about it. It is soft and actually kind of cute and only lasts couple seconds.


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## Vwbeamer (Jun 16, 2008)

Wow, those are nice batteries. most 100 ah batteries weigh in at 70-75 lbs, so you are getting another 55ah for just 5-10 lbs!

Can i ask how much they cost and where did you get them?


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## dimitri (May 16, 2008)

I just checked US Battery Web site for dealers in the area, called the closest dealer and got a quote $2000 for 12 batteries with free drop shipping to my door. They delivered same day, which was a nice surprise. Delivery guy was wondering where am I hiding all these golf carts that need 12 batteries


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## rctous (Jun 18, 2008)

I was at our club meeting and I also asked about the power steering motors ,,, One of the guys said they wer using tread mill moters straight off the traction battery. He also said they can be forund for 30 bucks,,, I am certainly going to give it a try , hesck at that price why not!

Brian


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## ClintK (Apr 27, 2008)

dimitri said:


> Well, after 3 weeks of hard work, my Miata hit the road today. Let the count of electrical miles begin, I wish I could reset the odometer



3 weeks? I'm hoping to get mine done by Christmas!

Congratulations though!


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## ElectriCar (Jun 15, 2008)

Man that's nice! Great job! and I like the battery racks as I've been wondering about that. 

I'd get that PS going so the missus doesn't lose her enthusiasm! Maybe you can put the pump on a switch or speed control so you use it only when going slow or such.

Enjoy!


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## PatricioIN (Jun 13, 2008)

I have a 94 Miata I've been looking at very closely just to get an idea of how to fit in batts... I was wondering why you chose to leave the fuel tank in place? Also, did all that extra weight take the Miata out of your Miata?


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## Uncle Joseph (May 7, 2008)

Congrats! Great job on the conversion. Looks like it took some serious shoehorn to get those batts in there! I can't wait to join the ranks next year with my Vibe.


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## dimitri (May 16, 2008)

PatricioIN said:


> I have a 94 Miata I've been looking at very closely just to get an idea of how to fit in batts... I was wondering why you chose to leave the fuel tank in place? Also, did all that extra weight take the Miata out of your Miata?


To remove fuel tank you must remove rear axle, which was too much work and not worth the effort in my mind. I couldn't use that space anyway since batteries won't fit there, so I only lost potential weight reduction of maybe 20 pounds, I can live with that. If one day I need to remove the axle for some reason, I will take the tank out.

As for Miata handling, lack of PS bothers me more than extra weight, plus I only drove few miles so far, ask me again after I fix PS and put 1000 miles on it.


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## Andrew Carson (Jul 7, 2008)

You know you could always attach a small motor to the odometer gears and spin it up until it turns over.. then you could "start" again at 0... just an Idea.... Congrats on the progress though! you should post your purchases and where you got them, it sounds like you found some good deals.


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## dimitri (May 16, 2008)

Everything was purchased from www.ev-america.com , their service and prices were good, although like most EV suppliers they struggle to keep things in stock these days 

My first trouble came last night, Quick Charger died on me, only after 2 uses. Called EV America today, getting RMA info to return it. Will be getting Zivan instead. They originally offered me to buy Quick Charger as a better deal, but the charger can't compare to Zivan at only 20% cost difference, its very heavy and apparently not very good quality. Hopefully be back on the road in few days


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## Andrew Carson (Jul 7, 2008)

bummer on being grounded... but hey while the car is in the shop you should roll over the odometer, there is a good site of a guy doing it with a drill 

http://auto.howstuffworks.com/odometer1.htm

enjoy


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## judebert (Apr 16, 2008)

Your Curtis should probably not get that hot after such minor driving. (Carrying over stuff I read from the EVDL, now.)

I believe your problem is the low RPM you're using. Electric motors like to run around 3000-4000 RPM. It keeps the air moving in motors like the ADC, helping to keep them cool. So, just about where you'd be shifting your ICE, you should be keeping your EV; you can usually do around-town driving in 2nd and keep 3rd only for speeds above 45mph.

Additionally, low RPM requires more torque. Torque requires current. Current requires big silicon, big wires, and inefficiency, generating more heat. At high RPM, you need less current, and therefore everything runs cooler.

The big caveat: don't over rev your motor! It'll literally fly apart! (I know from experience.) Your tachometer is your friend. If you don't have one, find the gear ratios of your car and calculate the speed at 5000RPM. Shift around there, or earlier if you're hearing rattling noises from the motor.


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## Bowser330 (Jun 15, 2008)

judebert, your post made me curious, maybe others could benefit from this too.

can you compare and contrast shifting in a gasser to shifting in an EV?

since the torque is from 0rpm and the horsepower curve is reversed i am confused on the optimal weigh to drive an EV...

optimal for perforamance lets say and optimal for economy...

Thanks!


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## Coley (Jul 26, 2007)

As others have said "Congratulations", from me.

Your shop looks great also.

You probably still have the "grin" and that is great.


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## judebert (Apr 16, 2008)

Bowser330 said:


> judebert, your post made me curious, maybe others could benefit from this too.
> 
> can you compare and contrast shifting in a gasser to shifting in an EV?
> 
> ...


Well, as my EV has had multiple problems, I haven't had much experience. So I'm pulling from the EVDL, here. What I'm covering is driving a DC series-wound motor -- others have different characteristics. Specifically, the ADC 9" motor.

Having a tachometer, battery ammeter, and motor ammeter is very useful for optimal driving.

Shifting is slightly different than an ICE: _first_ you let up on the accelerator, _then_ you depress the clutch (in an ICE, you usually do these things at the same time). You shift gears. To re-engage, _first_ you let up on the clutch (you'll get a little 'boost' as the flywheel dumps its energy into the wheels), _then_ you push the accelerator. In an ICE, many people "give it a little gas" to prevent lugging the engine; it's almost necessary to do that from a standstill. In an EV, that can be disastrous! The unloaded motor will spin up rapidly, and can fly apart if it goes too fast!

*Optimal Performance*
We're really talking about "best acceleration" here. As you said, DC series-wound motors get best torque at 0rpm. They also pull a lot of current out of the batteries to produce that torque. You'd want to keep the revs low and provide *lots* of power from the batteries. You'd need a big controller to dish it out. 

Put it in 1st and stomp the juice. (Most likely, your wheels will spin; in that case, start over from 2nd.) Watch the gauges; your controller should be giving its all, producing its max current. When your controller stops dishing out its max amps, shift to 2nd. Try to keep the controller at full output. 

Of course, you must also watch your tachometer to prevent over-revving the motor. And your batteries can only supply so much current; especially in higher gears, they may be unable to cope with the controller's demands. Don't shift until the controller is unable to increase its current and the batteries are. 

Expect shortened battery lifetime. Expect *lots and lots* of heat, eveywhere, batteries, controller, motor, and wires. Use big wires. Use big batteries with high Ah capacities. And expect a lot of noise -- not from the motor, but from screaming tires and passengers as the surprising low-end acceleration hits.

*Optimal Efficiency*
This is the way I drive, so I know more about it. The idea is similar to an ICE: run the motor at its most efficient point as much as possible.

Pretend there's an egg between your foot and the accelerator. Put the car in 2nd and lightly press the pedal. Never press hard enough to break the egg. Your Curtis may whine, but that's okay. It's just a minor distraction. 

Keep your eye on the tachometer. When you reach 3500-4000, you're in the most efficient range. Your motor is blowing air past itself, keeping itself cool; you're not producing much torque, so your batteries aren't sagging from current load; your controller isn't heating up much because it doesn't need to shunt so much current.

If you're not going fast enough, accelerate (egg!) to 4500 RPM. Shift to the next higher gear. Keep "accelerating" until you get to the 3500-4000 range. Keep it there as long as you can. If it goes below 3500, shift down to accelerate.

Look far ahead and watch your rear-view far behind. With practice, you'll be able to see the lane-changes you'll need to make a minute or more in advance. Pick a moment when you can switch lanes without slowing down or speeding up. Let the traffic flow around you; they can waste as much fuel as they want, but we're saving it. 

Know your route. Learn the stop signs and stop lights. Soon you'll know when a light is going to change, and you can adjust your driving take advantage of those situations to avoid acceleration or deceleration. Figure out how fast you need to be going at various landmarks to make it to the next light. You can coast a long way in an EV, so take advantage of it.

Some ICE drivers take advantage of "hypermiling", which encompasses all these techniques and a few others. In "pulse and glide" driving, they accelerate slowly to a top speed, turn off the engine, and coast to a bottom speed. This is not necessary in an EV, and may even be detrimental, since you'll use more current during the acceleration phase, and your motor isn't inefficient enough to make up the difference when it's off. Coasting is free energy, though. Use it as much as you can.

*Conclusion*
Hope that helps.


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## Andrew Carson (Jul 7, 2008)

THAT WAS INCREDIBLE!!!!! 

one of the most beautifully and elegantly written posts I have seen on here! please give us more!


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## greg88 (Jul 16, 2008)

dimitri said:


> Does anyone know of any electrical PS pump? I am not going to add a pulley to main motor, I hate to do that.


Toyota MR2 has an electric power steering pump. I'm new to these forums though... so that may be common knowledge. MKIII Supra guys sometimes switch to the MR2 pump. It allows them to run a front facing intake manifold and retain air conditioning.


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## ACARIZONA (Jun 27, 2008)

Nice job. I am looking to get started. Developing a Project Plan now. Have availability to lots of Miata and VW rabbit donor cars. Looking at all options and costs. Hoping to do this as reasonable as I can. Also have a 48 mile roundtrip communte I would like make without charging. Any thoughts on the subject would be appreciated.


Andy











dimitri said:


> Thanks everyone for your kind words
> 
> Each battery weighs 80 Lb , 155 AH , making a 144 V pack of 12 batteries total capacity of 22 kWh. I plan to stick to 80% DOD as recommended , with occasional 70% if need be. I hope to get 35-40 miles per charge at least. I just drove it for 18 miles today and voltage went from 154 at full charge to 143, so I should be OK with my range, considering batteries are new and still breaking in.
> 
> ...


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## dimitri (May 16, 2008)

Andy,

I can't comment on the range yet since I have not determined mine yet, but 48 miles is really pushing it for lead sled, and since you want to be at reasonable cost Lithium is not an option just yet.

I bought everything at EV America which is in your back yard, so you might wanna check them out, their prices were the best I could find for good quality parts and I like their approach to motor coupling using old clutch plate.


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## Bowser330 (Jun 15, 2008)

judebert,

Thank you friend. That write up was more than what i was expecting, and i read every word twice to make sure i grasped it all. especially the performance part jeje...


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## PatricioIN (Jun 13, 2008)

I noticed ebay has a restored 1990 Miata for sale right now from someone who says he has done a few conversions... 11 12volt batts and only a 15-20 mile range with brand new batts... Tempting, but that range is very low IMO. Just an interesting sidebar to this thread though : )


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## dimitri (May 16, 2008)

judebert said:


> find the gear ratios of your car and calculate the speed at 5000RPM. Shift around there, or earlier if you're hearing rattling noises from the motor.


Found this nice link http://www.idsfa.net/miata/gearing.html

Using the data and formulas applied to my specific car I found cruising and max speeds for each gear as follows, max is where to shift to next gear.

Cruising ( 4000 RPM ) - 2nd 33 - 3rd 47 - 4th 62 - 5th 77
Max ( 5000 RPM ) - 2nd 41 - 3rd 59 - 4th 78 - 5th 96

Once I test these I will mark shifting points on speedometer, so my wife can follow them 

BTW, Zivan charger showed up at my door today, its humming along now charging the pack, will be back on the road soon


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## judebert (Apr 16, 2008)

_*WARNING!*_

Although you have used the appropriate formulas to determine shift points, *check your motor documentation* to ensure that you've got the right limits!

For instance, NetGain recommends an absolute max of 5500RPM on their 9" motor. The numbers above are my recollection of the Advanced DC FB1-4001 9" motor, which has been said to run reliably at 5600RPM, and has charts and data showing RPM up to 8K. On the other hand, folks have seen them fail at 5000RPM. Motors will vary by manufacturer, size, and other factors.

If you exceed the maximum speed, your motor _will_ fly apart, requiring a complete rewind and rebuild or new motor. You have been warned: I will not be responsible for damage to your motor or any detriment to your physical or financial well-being.

Now that we've got that out of the way, good luck! I'm gratified that so many people found the little how-to enlightening. Just make sure to adjust the numbers according to the manufacturer's specs for your motor.


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## dimitri (May 16, 2008)

judebert said:


> If you exceed the maximum speed, your motor _will_ fly apart, requiring a complete rewind and rebuild or new motor. You have been warned: I will not be responsible for damage to your motor or any detriment to your physical or financial well-being.


Darn disclaimer, I was going to sue you if my motor blew up 

Seriously, after seeing your pictures of motor pieces, I will pull back my shift points to 4500 RPM. Better safe than sorry...

Thanks for all the info and sharing your experience.


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## Bowser330 (Jun 15, 2008)

Back on Topic, tell us more about the Miata!


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## dimitri (May 16, 2008)

I am back on the road 

Installed Zivan charger, Ammeter and Voltmeter, charged up the pack overnight, ready to go in the morning.

Yesterday I calculated cruising and shifting points based on 4000 and 4500 RPM respectively, then I marked them on the speedometer. This will help me drive at optimal RPMs. I also marked voltmeter at full charge, 80% DoD and 100% DoD, this will help to stay within limits.

Its Saturday, so I decided to test my work commute, 32 miles round trip. All went smooth, starting in 2nd gear, shifting to 3rd at 37 mph, keeping an eye on the ammeter, etc. Most of my commute is on 45 mph roads, so I try to stay with traffic in the right lane at 45-50 mph, which is right at my sweet RPM spot in 3rd gear.

One stretch of my commute is on 55 mph road, so I got to use 4th gear for couple minutes at 57-60 mph, nice 

Ammeter jumps to 500 momentarily from dead stop, then stays at 350-400 for few seconds while I get to 25-30 mph, then floats between 75-200 depending on the road incline, speed, etc. Voltmeter sags, but recovers quickly at stops or during coasting.

Got to the office parking lot, 16 miles, voltmeter is at about 60% mark between my marked points, yeehaa  I can get back home.

By the time I got back to my garage, voltmeter was still a tad over my low mark of 80% DoD, so I guess I could go another 3-5 miles, which would make it a total range of 35-37. Note, batteries are brand new, after 30 charge cycles I might even get to 40-45 range if I'm lucky 

Clutchless shifting is very easy, let go of gas and give a second before gently pushing into next gear, no troubles at all.

Handling is a little tough without PS, I already bought PS pump from Toyota MR2, will be working on that later.

I am definitely feeling extra weight, like driving a minivan full of people, but I guess I expected that, so its OK. Passing gas stations will cheer me up enough to forget about extra weight I am carrying


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## RKM (Jun 9, 2008)

Dimitri,

Again congratulations!

Not only have you made record time on your conversion, you've made it look easy!! It's great to hear of a first time success story. You, KiwiEV and others are becoming folk heroes in the EV community. Glad that your maiden commute went so well.

Rob


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## lazzer408 (May 18, 2008)

I'm probably the Miata guru around here. I built a turbo '94 laguna blue that's doing 275hp at the wheels and it's still 225hp short of the goal. 

As far as I know power steering rack has to be modified to truly bypass it. 
Talk to Flyin' Miata 1-970-464-5600 they should be able to help you. If you want to swap out a manual rack let me know and I can point you in the right direction to find one cheap.

Is there anything left from the old engine? I might be interested in buying some of it off you.


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## Coley (Jul 26, 2007)

I would be cautious about running the pack too low and also keep it out of 4th until the pack is better broken in.
Damage can occur really easy and has no warning.....


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## notnull (Jul 30, 2008)

Nice conversion.

I am getting ready to pull the motor out of my 1990 Miata and wanted to see if you could post a bit more information about your motor mount. I will be using the same motor. Is it just one of the universal clamp motor mounts and then you had to fabricate something to attach it to the existing motor mounts? 

Thanks,

Steve


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## dimitri (May 16, 2008)

I don't know if its universal mount, its a standard one EV America sells, I think it was made originally for S10 conversions. I used 2 pieces of 2" steel angle about 5" long to connect the mount surface to the original Miata engine mounts. Here is the pic, hopefully you can make sense of it.


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## notnull (Jul 30, 2008)

Thanks, that is exactly what I wanted to see.

Steve


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## dimitri (May 16, 2008)

Well, finally an update on the Miata. Power Steering is now working again, using Toyota MR2 Spyder electric PS pump. This pump is awesome, once I figured out how to wire it. I will post schematics in its own thread.

Also, after the car weigh in at 3200 Lb at the weight station, I decided to park it until I improve the suspension. After much research and consulting with local Miata club, I ordered coilover kit from Ground Control, which sells adjustable custom springs. I told them I need 1000 Lb over stock weight, so they calculated approproate spring rates and made them for me. Also, bought a set of KYB AGX shocks, adjustable, naturally I set them at highest settings.

Last night I got shocks and springs installed, twice actually, after I forgot to put one rubber bushing in each one, I had to take them out and redo everything. But its all paid off.

The car is handling even better then stock now, combination of PS and new suspension greatly improved how it handles, I hardly feel additional 1000 Lb of lead now.

I know people would want to know the costs, set of Ground Control springs was $400, set of KYB AGXs about $320 on Ebay, PS pump also on Ebay was $250.

At this point Miata is all done, since I promised my wife not to spend any more money on it until I pay off credit cards


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## joseph3354 (Apr 2, 2008)

dimitri said:


> At this point Miata is all done, since I promised my wife not to spend any more money on it until I pay off credit cards


using the $5-$6 a day you used to spend on gas it won't take too long. 

again,congratulations!


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## e_canuck (May 8, 2008)

Hello Dimitri.

Congrats on the Miata.
I like your pics. I am so envious.

About the mr2 pump, when you do publish the diagrams. Could you put it as an article in the wiki? It will be a recurring thing. I know I whant to refer to it.

Thank you for the past and future post.

DP


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## outlooker202 (Jul 16, 2008)

dimitri said:


> Well, finally an update on the Miata. Power Steering is now working again, using Toyota MR2 Spyder electric PS pump. This pump is awesome, once I figured out how to wire it. I will post schematics in its own thread.


Please provide a link to that thread (so it can be easily found)


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## dimitri (May 16, 2008)

Here is the link to the PS pump thread in tech discussion forum

http://www.diyelectriccar.com/forums/showthread.php/electric-ps-pump-mr2-17600.html

I am also planning to create a Wiki article on it.


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