# Planning... 1990 RX7 Roadster



## Duncan (Dec 8, 2008)

Hi
_upgrade to a warp 9 or 11 motor,_

The only difference I can see is the advanced timing (which you can do yourself) and a nice paint job

So an OpenRevolt would do for either

I have the 500amp OpenRevolt - its a nice unit, the Soliton is much nicer - but also much more expensive

The 1000 amp unit is still a work in progress - hopefully it will be ready soon (I want one) 

My car is also a permanently open one - no problems if its cold put a coat on


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## dougingraham (Jul 26, 2011)

You will want 1000 amps with either of those motors. The 2nd gen RX-7 is a bit heavier than my 1st gen. I have a WarP9 with a Soliton 1 and as an experiment I turned the motor current limit down to 500 amps. When configured this way it is adequate for driving around town as a commuter car. You can reach highway speeds but I would not call it quick. At 700 motor amps it feels like my other 1st gen which is still rotary powered. At 1000 amps it is very much an enthusiasts ride. About the only thing I would like is a bit more voltage but doing this adds weight which is counter productive. 

If I was going to do it all over again I would use a Warp11HV and put in 98 60AH cells to get the voltage up to the controller limit. You can't do this with the open Revolt controller. It is limited to something between 40 and 50 cells, not sure exactly what the limit is. This would be the performance option. The car will end up perhaps 50 lbs over stock weight and have a range of 50-60 miles depending on how you drive.

Keep the clutch. It is a little slow to shift up without it. You have to goose the throttle when in neutral to downshift. You indicate you have done this with the ICE but it is slower with the electric because there is nothing slowing the motor down so it takes quite a bit longer for the speed match to occur. If you want a performance build you will want to keep it. In driving around town I can just leave it in 3rd. This lets me redline at just around 70mph. If I want to spin the tires I use 1st. It almost has no other purpose. If I am giving demo rides I start out in second.

What you will find is that the stuff you take out is so much more complicated than the stuff you put in.


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## VillageIdiot (Nov 24, 2013)

Thanks for the replies. Both of you mentioned the Soliton controller so I've done some reading and watched some videos on it... looks like a winner to me. Looks like a pretty nice controller. I hate to say it but I'm a sucker for features... I like seeing cool stuff like the logging features. I've had many many years experience in mobile audio/video/security along with a carputer many years ago... the thought of a digital dashboard is very appealing to me. Do any other controllers have the logging features? If not, what other options are there to collect this information for such a digital set of guages are there? I'll keep looking into the controllers.

So it looks/sounds like starting with the right motor in the beginning is a must. The Warp 11 was my thoughts for ultimate end motor (short of the daydreaming for the Siamese setup... a man can dream, right?). Obviously everything can change but probably safer to say the controllers are more likely to change over time than the motors so motor should be first, right? Just like battery prices as well as options/technology have faster change and shorter shelf life so they should be the last purchase.

If keeping the clutch, safe to assume that with the amount of torque that I'll need to go with a high performance clutch and pressure plate? 

You said that I'll find out the stuff I take out is so much more complicated than the stuff I put back in... can you elaborate just a bit? Not sure I understand... this could mean so many things. Could be the obvious thing that the simplicity of the electric drive system is so much simpler than the electronics of the rotary system I am replacing... which I am first hand experiencing as I help my 17 year old son rewire his 1988 RX7 as we put a new motor in it. It could also be a warning that taking too much out of the donor car might pose problems. Just not sure what you mean. I'm sure you have experiences that I don't yet have.

Planning process is definitely a great, and educational, time. Not to mention much cheaper than making costly mistakes of not planning!

Thanks much!

Randy


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## dougingraham (Jul 26, 2011)

VillageIdiot said:


> If keeping the clutch, safe to assume that with the amount of torque that I'll need to go with a high performance clutch and pressure plate?


It was recommended to me to do this but the pressure plate in my car was in good shape and the clutch disc had been replace about 40k miles before my conversion and looked to be in very good shape so I elected to keep the OEM components. I have not had any problems with slipping. I am guessing that the reason this worked for me was I still have stock 185/70-R13 tires on the car and they let go before the clutch does. Also in an EV there is no reason to ever slip the clutch when you take off so you are not transitioning from dynamic to static friction which is where the trouble normally occurs. Having said that it would not be out of order to replace it with a heavier duty clutch and pressure plate if it needs replacing anyway. The cost difference is minimal and you don't use the clutch all that often so the stiffer pressure plate is not a fatigue issue for street driving. If you were converting a VW with a 40HP engine and 40 ftlb of torque to a WarP9 with 150HP and 277 ftlb torque you would have little choice but upgrade these components because the OEM ones could never handle it. The Rx-7 street parts were intended to handle power and torque levels not too far below these EV power levels. I think your car had when new about 160HP and 150 ft-lb torque.



VillageIdiot said:


> You said that I'll find out the stuff I take out is so much more complicated than the stuff I put back in... can you elaborate just a bit? Not sure I understand... this could mean so many things. Could be the obvious thing that the simplicity of the electric drive system is so much simpler than the electronics of the rotary system I am replacing... which I am first hand experiencing as I help my 17 year old son rewire his 1988 RX7 as we put a new motor in it. It could also be a warning that taking too much out of the donor car might pose problems. Just not sure what you mean. I'm sure you have experiences that I don't yet have.


This wasn't meant to be mysterious. The ICE and all its systems (ignition, exhaust, fuel, cooling, emissions, charging) is so complicated compared to the Battery/Controller/Motor hookups you will be amazed. You will probably want to reuse some of the wiring harness stuff so it might be a good idea to label the wires when you take them off. The Mazda service manual will help greatly with this.


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## elevatorguy (Jul 26, 2007)

I haven't had any clutch issues with the stock setup in my 86 rx-7 and I drive it pretty hard as it is not a commuter. I run the Soliton at 800 amps, 165 volts and a Warp 9.
I agree with Doug, to do again I would go higher voltage but my original controller was only good to 165 nominal.
Planning is a good idea, I had a few hiccups in the build, change of controller, power steering etc. My biggest concern was building so I could update or swap parts as needed without full rework of the mounting setup.
The mazda makes a good conversion, I will look forward to watching your build.

Jerry


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## VillageIdiot (Nov 24, 2013)

Yeah, I've already seen first hand how intricate the harness is in the RX7. I stumbled into my donor car as my son has been building his 1988 T2. He purchased my 1990 convertible for the newly rebuilt NA motor with a mild port. We have spent a couple days removing full body and motor harnesses from donor car and transferred into his car. As you could expect, there is little similarity in the two harnesses only two years apart. I'm about ready to start modifying his harness with plug sets from his old harness so that we can get door harnesses to plug in as well as all HVAC controls and gauges and controls will all be functional. I guess all of this means that I'll be plenty familiar with the harnesses and will be able to get whatever I need up and running.

Definitely not for the faint of heart. I can't wait to get into NEW system wiring later in the build. Think that part will be a breeze in comparison to what we are doing right now.

Thanks for the input guys. I'm sure I'll have plenty more questions... but I'll be digging around for answers before I start asking what's already been asked a thousand times.

Have a good day!

Randy


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## fanimasuo (Dec 30, 2013)

Seems like a good idea. Post pics whenever you are ready.


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## VillageIdiot (Nov 24, 2013)

Holy crap! I didn't realize I started reading and planning and daydreaming of my conversion so freaking long ago! My last post November 2013!  

I have been doing tons of reading different blogs, forums, and just general sites since I decided this was going to happen. I have been ridiculously busy at work since then. Barely enough time for family and work but I think its time for me to start working on the car.

I'm going to start cleaning up my car finally. Since I gutted the complete wiring harness from my RX7 to put in my sons '88 RX7, I am starting with NO harness. I think I like this idea as with the time I spent rewiring his car, I know my way around the car very well.

I will start this tedious process tomorrow morning and will push through over the next few weeks... depends on how much time I can get away.

Here are some of the items that I have decided since the beginning...

I think I have decided on the Soliton 1 controller and figure it is not cheap but on the other hand, from all I have read, will serve my purposes for now and future plans.

I think I want to EVENTUALLY go with a dual motor set up and I am curious about where to go with this. I see plenty about the WarP9 being set up for mating the shafts together... dual shaft, right? I have seen some instances of Kostov motors being available this way.

Question is... who else makes makes a dual shaft configuration? Is the WarP9 the best bet? 

What I want to do is build my transmission adapter with a "carriage" or "mount" that basically mounts to the trans and then extends to the stock motor mount locations. I am picturing a mount that has the space and support so that when the time comes, I can literally drop the second motor onto the "carriage/mount", bolt to the first motor and then mount the motor down to the mount. Has anybody done anything like that?

The next question I have is, if I go this route, as I build up my other parts and equipment, how should I go about batteries? I would expect that if I were to run (1) motor for a period of time on a battery pack, when I decided to add a second motor and up the pack voltage, I would probably want to start over with a completely new battery package so that all cells are of the same age and condition, correct? Would it make sense to go cheaper (lead acid or some kind of used or remanufactured pack) in the beginning and then at motor upgrade time, replace with a full NEW pack? Is that a dumb idea? Thoughts?

Other than that... lots of time spent just dreaming about the plans. I think my wife things I'm nuts. Truth is, I am! 

Catch you later!

Randy... THE Village Idiot!


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## arklan (Dec 10, 2012)

start with the voltage u eventually want so that u dont have to increase it later
u can limit the motor voltage with the soliton and even run 2 motors from the soliton because the soliton can do high voltage, 320vdc I think? or is that zilla? so the second motor would be in series
anyway u can do everything u want from the beginning and just add the extra motor later
if u want to add more batteries later u will have to individually parallel them with each battery u have
so if u start with 100cells at 40ah (320v) then u would need to get 100 cells later, not 20 or whatever


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## dougingraham (Jul 26, 2011)

I just reread the whole thread. It seems like you have mixed goals and I understand that. You sort of want a weekend toy, not really a daily driver. You want it to be performance oriented eventually but you don't mention what kind of performance.

I would try to pin down the goals because it makes recommending solutions easier. Mixed goals like 10 second quarter mile and long range (another thread) can only end up costing a big bucket of money.

Are you going to put in a roll cage? Seems like you want a car that you look good in rather than something dangerous enough to need the rollover protection. Do you want a car that has as much or more performance as your son's 88 TII? Or would the performance level of the original car be good enough? Are you still thinking about 50 miles for the range? Your early comment about thinking about leaving off the clutch is a hint that performance is not all that important to you. I say this because a shift with the clutch takes around 1/3 second and a clutch less shift takes around 2 seconds.

People tend to want it all so defining your goals for the car may be difficult. And they could change after you finish the car and drive it a while. My 30 year old 7 was not drive-able as a daily before the conversion. I can't imagine not wanting to drive it daily anymore.

With a car as light as the RX-7 you don't need two motors for a fair weather car unless you really need extreme performance. If you want a car that can match or exceed the original vehicle in every aspect except for top speed a Warp9/Soliton 1 combo will do that with the correct battery pack. If you were determined to not use the transmission then two motors is essential to get the torque you need. A single motor would be stressed pretty badly in that situation and you would need a 2000 amp controller.

Here are my recommendations and is what I would do today with my own car.

For the battery:

Option 1: 94 CALB CA60FI cells in series. This pack will have a peak voltage of 320 volts and a nominal voltage of 300.8 volts (94cells * 3.2 volts). It will have a capacity of 18 kwh. If driven in a responsible manner should have a drop dead range of about 60 miles with an 80% range of 48 miles. The pack will weigh more than 418 lbs (not counting the intercell straps and boxes). It will have a peak output of 180480 watts (250 HP). Cost of $8366 plus shipping which includes the inter cell electrical connections.

Option 2: 94 CALB CAM72FI cells in series. This pack will have the same voltage as the previously mentioned option. It will have a capacity of 21.7 kwh. If driven in a responsible manner should have a drop dead range of about 72 miles with an 80% range of 58 miles. The pack will weigh more than 403 lbs (which includes the inter cell straps but not the boxes). It will have a peak output of 173261 watts (232 HP). Cost of $13442 plus shipping which includes the intercell electrical connections.

The option 2 battery pack has more range and less weight but also a little less peak power at a higher cost.

Motor options:

Warp9: At 1000 amps and 170 volts you see 237 ft-lbs of torque and a peak input power of 170000 watts (228 HP).

Warp11 HV: At 1000 amps and 288 volts you see 291 ft-lbs of torque and a peak input power of 288000 watts (386 HP). In this case you would be battery limited in peak power.

Warp11: At 1000 amps and 170 volts you see 320 ft-lbs of torque and a peak input power of 170000 watts (228 HP). Same peak power as the WarP9 but significantly more torque.


The above are predicated on using a Soliton 1 for the motor controller. Higher currents can give higher torque values. The Netgain controls product can do 1400 amps and the Zilla 2K HV product can do 2000 amps. The batteries would limit torque at higher power levels but there would be performance advantages to either of these as upgrades.. At 1400 amps the WarP9 has 339 ft-lbs, the WarP11HV has 415 ft-lbs and the WarP11 has 460 ft-lbs of torque. At 2000 amps it is higher. But the mentioned batteries really can't do this except at lower RPM's.

When you go to two motors in all cases you would need to add a second motor controller or the motor controller becomes the limiting factor. A pair of WarP9's or WarP11's with a single Soliton 1 would be limited to 1/2 the nominal battery voltage so 150 volts at 1000 amps (motors in series) giving a total of 300000 watts (402 HP) but this would again be battery limited. With two controllers and enough battery to feed them the pair of WarP9's would have 340000 watts (456 HP) input to the motors.

Does a weekend only car with no roof need those kinds of power levels? Could a convertible RX7 handle those kinds of torque numbers without twisting the frame? That should give you more to think about.


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## VillageIdiot (Nov 24, 2013)

Doug- 

Thanks for the detailed reply and for your thoughts. You are right in the fact that I have some mixed goals. Mainly because I started out just wanting to motivate my donor car down the road at any possible level just for the sake of doing it. As time has progressed, and I have read and learned more, just moving is not enough. I would like to move briskly.

Would I like this to be a daily driver? Sure, but my biggest problem is that my weekdays are consumed by leaving home before 5:00 am and get home between 4:00 and 5:00 pm. I drive a company vehicle all day and will drive sometimes 100-200 miles a day. Evenings are family... wife and kids... which leaves weekends.

The performance you outlined with a single WarP9, Warp11, or WarP11HV sound like they would suffice. I unfortunatrly won't know until the time comes if that is enough. Prior to get remarried, my cars were always somewhat (if not extremely) performance related. A multitude of vehicles from GMC Typhoon, twin turbocharged Convertible WS6, to roadster super beetle with 2270cc turbo 914 motor as well as a Isuzu Vehicross with an LS1 shoehorned into it. Since marriage, we have gotten rid of all toys and survived with one personal vehicle and my company truck. Its time I had a toy back.

I digressed... the performance mentioned would probably be enough for me but knowing me, I COULD find myself wanting more later. That is where the thoughts of leaving room to MAYBE add a second motor later comes in. The battery prices thrown out there are in the ballpark I had been thinking so I'm still good. 

Anyway Doug, great food for thought. I'll continue to read, research, and dream a bit. Thank you for reading through my many thoughts. I appreciate your, and everybody else's, input, thoughts, and experiences.

Randy


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## VillageIdiot (Nov 24, 2013)

dougingraham said:


> ... The Netgain controls product can do 1400 amps...


BTW, with everything I've read and with what I already know about WarP motors, this is the first time I've heard of the Netgain controller... how is that possible? Unless I'm reading it wrong, the MSRP is comparable to the Soloton 1 but it has room to grow? Obviously at a cost, but hmmm... thanks again for the info.

Randy


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## dougingraham (Jul 26, 2011)

VillageIdiot said:


> BTW, with everything I've read and with what I already know about WarP motors, this is the first time I've heard of the Netgain controller...


I almost didn't mention it. There have been issues getting them repaired in a timely manner. It is not exactly the same company as sells the motors. I believe in general people are happy with them.


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## arklan (Dec 10, 2012)

arklan said:


> start with the voltage u eventually want so that u dont have to increase it later
> u can limit the motor voltage with the soliton and even run 2 motors from the soliton because the soliton can do high voltage, 320vdc I think? or is that zilla? so the second motor would be in series
> anyway u can do everything u want from the beginning and just add the extra motor later
> if u want to add more batteries later u will have to individually parallel them with each battery u have
> so if u start with 100cells at 40ah (320v) then u would need to get 100 cells later, not 20 or whatever


ok so to hyjack this thread, is there any reason this wont work?
the soliton1 and zilla both do 1000amps at 300v
the warp motors can do 192v but i think that voltage will over speed them?
putting the 2 motors in series will give 150v at 1000a to each motor giving 300kw
im guessing a car with this setup would be very fast  and would probably like an auto box


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## dougingraham (Jul 26, 2011)

arklan said:


> ok so to hyjack this thread, is there any reason this wont work?
> the soliton1 and zilla both do 1000amps at 300v
> the warp motors can do 192v but i think that voltage will over speed them?
> putting the 2 motors in series will give 150v at 1000a to each motor giving 300kw
> im guessing a car with this setup would be very fast  and would probably like an auto box


George Hamstra doesn't like to say 192 volts. If pressed Tom Brunka will say reluctantly say 192 volts with the correct brushes.

It isn't that 192 volts will overspeed the motor. You can do that with 24 volts no load on the shaft.

The motor controllers limit voltage that the motor sees. That is all they can directly do. Everything else is a side effect of this. For example if you have the motor controller set to limit the motor amps to 1000 it will ramp up the voltage and the motor RPM will increase and the current it is drawing will increase as the voltage rises. The motor controller will watch the motor current and stop increasing the voltage when the 1000 amps is reached.

If you place the motors in series, yes each will see 1/2 of the pack voltage but this only occurs when the motor controller is wide open. Your peak input power to the motors will be the sagged battery voltage times 1000 amps. If the sagged battery voltage is 300 volts then total input power will be 300 * 1000 = 300kw (402 hp) and each motor will see half that because each motor sees half the voltage. The downside is that because the voltage is limited to 150 the torque curve will taper off at a lower RPM than it would if you were able to apply 192 volts to each motor. A single motor with 192 volts at 1000 amps would absorb 192000 watts (257 HP) and because of the higher voltage the torque will extend to over 5000 rpm instead of the 3500 you would see with the 150 volts. And the additional 84 kw (112 hp) is why the drag racers go with a controller per motor.


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## arklan (Dec 10, 2012)

so zilla 2k and run the 2 motors in parallel


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## dougingraham (Jul 26, 2011)

arklan said:


> so zilla 2k and run the 2 motors in parallel


2 Zilla 2K's and run 2000 amps at 192 volts each. 768 kw (1029 HP) into the motors. Thats going to leave a mark.


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## VillageIdiot (Nov 24, 2013)

arklan said:


> ok so to hyjack this thread...


At least your highjacking went in a good direction. 

And yes Doug... that would leave a serious mark!

Randy


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## afb312 (Mar 9, 2011)

A skid mark for sure!


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