# Mazda MX-5 Miata (11HV) Build Thread



## somanywelps (Jan 25, 2012)

be careful with the RPM.

IIRC it's 3000RPM nominal, 5000RPM absolute redline for the warp 11HV.

Edit: 60Ah 3.2V batteries * 96 is 307V, and considering you want a solid 288V under load, you might get mad voltage sag.

Edit2: Inspect the Kostov K11 250V (and the Alpha version) and perhaps dual 9"s as well


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## EV-propulsion.com (Jun 1, 2009)

In order to use an 11" motor in a miata, the motor/transmission will have to be raised above it's stock position. Being that the car has the torque brace between the trans and rear axle effectively making the complete drive line one piece, just forcing the motor/trans higher will be stressing some mounting points, so keep an eye out for what is being stressed. You may wind up with some type of driveline vibration you didn't have before the conversion. We don't recommend anything bigger than the 9" because of this.
Mike
www.EV-propulsion.com


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## Yabert (Feb 7, 2010)

Hi NJ

I'm sure you have good intention about component choice, but I think you will need to learn a bit more.

I don't see any good reason to use a 230 lbs Warp11HV instead of a 150 lbs Warp 9 because the motor job is only to transform battery energy into rotating power (hp).

Example:

60Ah x 5c = 300A x 288v = 86Kw of peak power (not considering voltage sag)
120Ah x 5c = 600A x 144v = 86Kw of peak power (not considering voltage sag)

So, the battery power capability is your weakest link in both situations.
If you need a short range / high power conversion I suggest you to peek at A123 AMP20 cells.

Finally, using a 1000A controller instead of 600A one that will give you 40% more torque at low rpm (before than the limited battery power became a problem) and that is 40% more power at low rpm. 
So, faster acceleration... Not useless!


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## galeson (Oct 25, 2009)

The 11HV fits nicely in the older Miatas, no frame modifications, clears the steering rack, and there is no noticable vibration. The only downsides I can see are the extra weight over a 9 inch and that you need to remove the motor to get the transmission out. 
My understanding is that the 11HV uses the same armature as the 9 inch so the max RPM should be the same.
I agree about the A123's if you want to spend the time to assemble a pack.


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## drgrieve (Apr 14, 2011)

Just throwing some options out there.

If you can squeeze the room, evnetics have upped the max voltage to 350v. You can now consider 100 serial (up from 96).
I've considered the best match for Soliton Jr is the Kostov 220v. You should see 220*600 => 132kw. Not far off the Soliton Jr rating of 150kw. This is also a budget friendly combo.
If you want more oomph, then a warp 9 with a Soliton 1 should get to around 160Kw which would be your battery burst limit. (10C burst - 20 to 25% sag this is WAG).
Personally the 11HV or the K11 250v is for a much higher power set up 200 to 300kw+ - For a nice light weight car the Kostov 220v at 45kg sounds nice - cheapish also at ~1700.


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## rochesterricer (Jan 5, 2011)

Do folks end up having many trans issues in high power converted Miatas? I know in the turbo Miata world the stock trans isn't known for being very strong.


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## DJBecker (Nov 3, 2010)

I don't see an 11" motor being a problem for driveline height. It will just barely fit using the stock motor mounts+brackets with a box frame. The more significant limit is fitting behind the front sway bar.

Do you see value in the EVMiata "kit"? It's just a set of simple brackets. Every one needs to be modified to match your components. You'll probably save time by just starting from scratch. The kit omits all of the difficult parts of the conversion.


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## njloof (Nov 21, 2011)

Thanks for the quick feedback, everyone.

Just to provide some additional context, I've attached dyno tests for the 1.6l engine currently in the car (sourced from http://blogs.insideline.com/roadtests/2010/04/1994-mazda-mx-5-miata-baseline-dyno-test.html). Add 15% to that to cover the increased weight of the car, and that's my performance goal to meet or exceed.

Keeping the transmission means there is not enough length for a dual series motor setup.

One thing I don't understand is why you would build a 144v x 120Ah pack over a 288v x 60Ah pack. Even if you're targeting a 170V motor, the controller can modulate the pack voltage to the motor's limit, with a corresponding increase in amperage. That would be pretty voltage sag proof, no?

Thanks for the suggestion on the Kostov motors, definitely worth a second look.


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## njloof (Nov 21, 2011)

Yabert said:


> Finally, using a 1000A controller instead of 600A one that will give you 40% more torque at low rpm (before than the limited battery power became a problem) and that is 40% more power at low rpm.
> So, faster acceleration... Not useless!


Took me a while with a spreadsheet and the dyno data for the motor to finally understand this -- and, of course, you're right; with a 1000A controller I can put out 1000A even from a 5C/60Ah pack at voltages lower than the maximum. Thank you for pointing this out.

A 600A controller would give me 173 ft-lbs from the motor at the low end, and a 1000A controller would give me 290 ft-lbs. To rochesterricer's note, some of the nicer turbo kits for the Miata are in this range as well; for what it's worth, Flyin' Miata says they have had no reports of transmission issues with their turbo kits but they do say that a stronger clutch is a must.

If I end up with the Kostov motor I can plow the savings into getting the Soliton 1.


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## Yabert (Feb 7, 2010)

njloof said:


> One thing I don't understand is why you would build a 144v x 120Ah pack over a 288v x 60Ah pack. Even if you're targeting a 170V motor, the controller can modulate the pack voltage to the motor's limit, with a corresponding increase in amperage. That would be pretty voltage sag proof, no?


You are right!
144v vs 288v was just an example.

But if you target 120-150 hp, I don't see reason to build 288v battery pack.


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## njloof (Nov 21, 2011)

Higher voltage, less amperage, less heat in the wires, no? Up to the motor's voltage limit, I mean. It just seems disadvantageous to end up feeding lower voltage to the motor at high RPMs.


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## njloof (Nov 21, 2011)

So I emailed the Kostov guys; they hope to have dyno numbers on the Alpha in a couple of weeks. I like the higher (5500 RPM) redline on their 11" motors.

The next best choice seems to be the K9" 220V. I'm still favoring the higher voltage to ensure I have enough torque at higher RPMs at reasonable amperage (~500A). 6800 RPM redline is as good or better than the ICE.

Right now I'm driving the car to get a feel for how it performs with the ICE. The insurance grace period ends in another week, at which time I garage it, file for "non-use" and drop the insurance. Then it's time to pull and sell the engine, not necessarily in that order.


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## MN Driver (Sep 29, 2009)

The redline for the 9" motors is 7000rpm, the nominal is 6800rpm. Basically what it means is that if you are feeding it 220v 176 amps and have a 42nm torque load at 6800 rpm it is rated for 31.2kw for an hour.

If you want to push any more than 176 amps through the motor at that speed you need a higher voltage pack than whatever would sag to 220v at 176 amps. From the chart in that other thread your peak torque is at 4500rpm or so unless you are pushing more voltage because the amps start to drop there. I'm not sure what the commutative limits are but 250v was fine according to Plamenator in the other thread but be sure you aren't going to go over 7000rpm. I'm looking to go with 100 cells of 60Ah with a Soliton Jr so that sag won't be an issue, although it's a 20kwh pack of prismatics so some care would need to be taken to be sure that I'm not drawing too heavily against it and getting the battery too hot through heavy discharge but then again I'm looking to convert a 1900 pound aerodynamic car pre-conversion so I'm not too worried, it'll get to 60 fast with a setup like that.


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## njloof (Nov 21, 2011)

Prepping to pull the engine at the end of the month. Once that's done I'll attach a mockup of the motor to the transmission and start looking at the fitting issues.

Early specs on the K11 Alpha look pretty good. Integrated forced air gives me a little more confidence about pushing 1000A at low RPMs. I think that's nominal 5800 RPM I see on the site? If so, that seems pretty reasonable; that would be ~100 MPH in 5th. K9 220V is a very decent fallback if the mechanical issues of the 11" motor prove more hassle than they're worth. I'm curious as much as anything else at this point; I may still choose the smaller motor in the end.

This thread needs some pics soon. So far nothing to show that doesn't look like a stock Miata.


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## njloof (Nov 21, 2011)

Compression checked the motor... not perfect (210/180/180/210), but not bad for a 20-year-old engine with 145k miles. Looking around for a buyer on the Miata forums.

Received the Warp 11" mockup from EV Source. Once we have the engine out we can reassemble this with the transmission and do a test fit. I want to be absolutely sure the larger motor is going to work. If I end up with the Kostov 11" motor I'll have an extra .2" of clearance on both sides, but I'm hoping it won't be *that* snug a fit.

Also received the hub and adapter plate. Kerryman, if you're watching, cancel your order and get one from EV Source/CanEV instead... mine arrived in about two weeks from the order date.

Next weekend: drain, disconnect and pull engine.

FWIW, the EVMiata folks just hired a new welder, so my kit may have some delays. The part I really need first is the motor mount.

To DJBecker's point: the EVMiata kit has already saved me time in the planning stages, since it lets me predict how many batteries I can fit, and where; and it takes most of the welding out of the build, which is not my strong suit. Plus, those guys have been very supportive and answered lots of my questions, both through their step-by-step instructions and many emails.


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## njloof (Nov 21, 2011)

Well, seven hours later, my friend Andy and I wrestled the engine out of the car. Getting at some of the transmission bolts was... amusing.








Andy brings his heavy equipment.








Catching the wild 1.6L ICE.

Next step is to transfer the flywheel/clutch/plate to the 11" motor mockup and see what it will take to fit it. It's pretty clear it will hit the steering rack first, so that'll be the thing to look at.


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## DJBecker (Nov 3, 2010)

You didn't pull the motor and transmission out still joined? It would have been easier that way. You'll eventually need to pull the transmission out anyway.


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## njloof (Nov 21, 2011)

Transmission stays, at least as far as the EVMiata manual says. Once the hub and adapter plate are on the motor, I mount it and bolt it back on.

Light progress in the last couple of weeks. Took the clutch/plate and flywheel off the engine:









... and drained the gas tank. Every set of instructions said to loosen the drain plug until your arm is soaked in gasoline, and they were right. A gallon and change later and I put it back in. Have to figure out a clean way to fill the tank with soapy water (siphon, probably) so that I don't set any remaining fumes on fire with the plasma cutter later.


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## Batterypoweredtoad (Feb 5, 2008)

I would suggest just dropping the rear subframe to get the gas tank out. Subframe removal is not that difficult.


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## EV-propulsion.com (Jun 1, 2009)

I second that about the subframe, it really should only take an hour to get out. Six bolts, two strut bolts, driveshaft and torque arm. Tie up the calipers to the body and its out.
Mike
www.EV-propulsion.com


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## njloof (Nov 21, 2011)

So noted about dropping the gas tank. I just disconnected the fuel filler lines so that would be a possibility.

So far light progress each weekend while I wait for the motor mounts, so I can test fit the 11" motor mockup, so I can order the 11" motor. Telling friends I am "building an EV" seems a little presumptuous still; all I've really done so far is "disassemble a perfectly good car."

But I've stripped the trunk, removed the exhaust, muffler, catalytic, ECU, radiator, mounts, tie-downs, heat shields... I have "Clean engine compartment" on my to-do list, but somehow that keeps getting postponed 

BTW, for project tracking nerds, I've got the whole project transcribed from the EVMiata manual into OmniFocus. Worth every penny. I may feel like I'm making slow progress, but stuff keeps getting checked off, so I'm getting somewhere. Also a great place to stash links to where I need to buy stuff when the time comes. Mental note: assume everything you order takes 10 weeks, no matter what anybody tells you.


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## njloof (Nov 21, 2011)

Got the mounts. I failed at photo duties this weekend, but here are the mounts, roughly positioned as they cradle the motor if you are facing towards the transmission.










So the angled edges facing towards you are what sit on the stock motor mounts, which I decided to replace after one of them crumbled under light pressure. Oh, good, I wanted to buy the stiffer ones anyway.

But: while the EVMiata.com site says that the mounts will accommodate an 11.5" motor, you would have to grind away significant amounts of metal (we estimated .4") in order for the mounts to fit along the long axis of the motor. They are meant to be snug against the motor but it was just too snug for the WarP 11 (mockup). Oh well, the Kostov was looking like a better choice anyway. At least the overall fit looks good; there was an inch remaining above the steering rack and an inch behind the swaybar; the K11 Alpha will easily be clear of both.

So, onward to ordering the motor!

Edit: to clarify, the Warp 11 is nearly 11.5" in diameter; the K11 is just over 10.5". So maybe the tiniest bit of grinding will get the K11 in place. It won't affect the structural integrity of the mount.


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## njloof (Nov 21, 2011)

A couple of months go by, and where am I at?

- Engine sold. Somebody had a Miata with a blown engine a couple of hours away. I fortunately had the more popular "longnose". He picked off a few unneeded components from the remaining carcass 

- EVMiata racks arrived. Nicely powder coated and look good. Will spray at least with matching primer. So in case I get stuck on motor issues I have a few good days of rack installation to fall back on.

- Found a deal on an AC24/DMOC445 I just couldn't pass up. It's not the demon the Kostov Alpha would be, but from looking at evalbum entries it can still be a good performer if you give it the voltage it wants (288V+). This shaves cost off the project, which will help me get it finished in a timely fashion.

- The motor has arrived and I am preparing to bench test it. I'm assuming I shouldn't need much current to spin it with nothing hooked to it; I have a plan for getting 120VDC/10A without batteries.

More soon. No pictures! Shame on me.


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## Ziggythewiz (May 16, 2010)

Standard test is to spin it at 12V, I don't know how many amps is typical. 120V at 10A unloaded is probably enough to make an IED.


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## njloof (Nov 21, 2011)

Ziggythewiz said:


> Standard test is to spin it at 12V, I don't know how many amps is typical. 120V at 10A unloaded is probably enough to make an IED.


In theory, yeah  The controller's minimum operational voltage is 100VDC though (according to the spec). And since it's AC it should be able to control speed even at low loads. If the throttle seems at all jumpy on the bench I'll mount the clutch and flywheel for further tests.


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## TEV (Nov 25, 2011)

Ziggythewiz said:


> Standard test is to spin it at 12V




Only for DC motors, AC24 it's an AC motor, the only way to spin it it's using the controller.


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## Ziggythewiz (May 16, 2010)

Sorry, missed the AC bit. What's your planned nominal voltage?


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## TEV (Nov 25, 2011)

njloof said:


> I have a plan for getting 120VDC/10A without batteries.


Kind of a dangerous plan so please consider those :

A 10A rated bridge rectifier need a heat sink to use it at 
10A
Also install 10A fuses before and after the rectifier.

When I bench tested my AC55 with UMOC440TF, it use 5A at 340V(from batteries) . You my get away with 10A at 120V.

Good luck.


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## njloof (Nov 21, 2011)

TEV said:


> Kind of a dangerous plan so please consider those :
> 
> A 10A rated bridge rectifier need a heat sink to use it at
> 10A
> Also install 10A fuses before and after the rectifier.


How about this:


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## TEV (Nov 25, 2011)

That is not a "plan", it's a device


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## njloof (Nov 21, 2011)

TEV said:


> That is not a "plan", it's a device


Fair enough. Well, it was a plan, and then it was an eBay auction, and then it was a device. 

It's reassuringly big and heavy with a steel case like everything used to have. Came with a 240V twist plug I replaced with a standard NEMA 120V/15A, and the DC output was an L1-15P. Output looked good on the voltmeter when I fired it up.


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## njloof (Nov 21, 2011)

(As received.)


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## TEV (Nov 25, 2011)

Nice. It should work for a test without a load on the motor.


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## njloof (Nov 21, 2011)

Well, I guess an update is long overdue 

Short version: http://youtu.be/LS1msnnkeLI

Longer version:

So, the project went through a "rebudgeting" process at home. Not a new story, I'm sure. It also brought the project back to a slightly more appropriate scope for a starter project, which isn't a bad thing.

So: picked up a DMOC445/AC24 combo for a decent price. From looking at evalbum, it looks like that combo can perform well, but only if you can give it enough voltage (144V setups seem to be underpowered, which makes sense given the controller's 170A limit). Overall I've been favoring higher voltage setups -- it's not without its costs (components that need higher voltage ratings), but overall hoping to get more power for less copper. My HV wiring is all 2 AWG, which should be enough.

Mounted with a Rebirth Auto adapter, with one caveat: it's not obvious from the site that the mounting holes don't go through the plate. This plays hell with evmiata's current mounting strategy, which is a couple of pieces that connect the motor side of the adapter plate to the engine mounts. So I had to fall back on their older mount, which bolts directly to the subframe. Much as I like the Rebirth adapter, if I had it to do over again I'd use the CanEV.

I was able to test the motor/controller on the bench using the ancient 110VDC/9A power supply I posted earlier. Then assembled the trunk pack, which is about 40% of the car's total capacity. I used 42 CALB CA40FIs, which fit well in the rack with room for insulation around the batteries and 1/2" plexiglass on top.

So: need to get the lithiumate lite powered up, need to get the EMW charger wired in, need to get the vacuum pump hooked up to the brakes, need to get everything mounted. Then I can road test a bit before investing in the other 63 batteries.

Progress! Woo.


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