[rickeolis]

Hi Qer, I really appreciate the input.
I had posted a while back with my desires for this project and nobody had much to say, but you are asking the questions I need to know:
I want the car to be quite powerful for each lap up to 5 minutes, without damaging any related parts (Batteries-motor-controller)
I would like performance specs similar to that of a Spec Miata, such as 0-60 under 5 seconds, top speed does not need to exceed 90 MPH, and on a daily drive should last at least 50 miles...
If you don't think the Warp 9 is the way to go, I would like to honestly like to know what kind of motor\controller package would be good.
Thanks again!

Rick

[EV-propulsion.com]

I think to get anywhere near this performance you will have to go to as high a voltage as possible, maybe using the high voltage warp11 (up to 288 volts) with a Soliton ? A transmission would still help, especially with using a warp 9 (& up to 176 volts).
mike
www.EV-propulsion.com

[Batterypoweredtoad]

What rear gear ratio are you using?

[Qer]

Ok, I'll bite, despite risking being flamed to crisps.

"0-60 under 5 seconds, top speed does not need to exceed 90 MPH" is not simple to achieve and you WILL be pushing things, probably even blowing things (batteries, motors, possibly even controllers) becasue that's what racing's about. To quote Plasmaboy: "...we blow things up, so you don't have to."

Anyway, the White Zombie does the 0-60 in 2.9 seconds and has a top speed at 1/4 mile of 114 mph. It achieves that with a Zilla 2kA and a siamese WarP but (and this is a big but) it can't keep it up! Drag racing is about seconds (with the possibility to cool things down between runs), you're talking minutes and pushing these kinds of kW for up to 5 minutes will be torture for the whole electric circuit.

So let's start from the beginning; batteries. As EVpropulsion already stated you want voltage, preferably north of 200 Volt, but you also want Ah because the maximum power you can drain by the pack is of course W=V*A and your maximum continuous Amps will be Ah*C. For currents that are getting awfully close to continuous I don't think you want to use more than 3C which means that 200 Ah will give you 600 Amps top and if you want more power you have to raise the Voltage. Your pack will be huge unless you go with A123, but then the price tag will be monstrous. You want to keep an eye on the pack temp too and might even have to cool it with fans because even though increased temperature has the advantage of reducing internal resistance and increasing it's efficiency it'll also kill it in the long run.

Then there's the next step, controller. I think you have two options, Zilla or Soliton (with a possible third alternative, Netgain). Zilla has a peak power of 1kA or 2kA but continuous Amps are "only" 300 versus "over 600". I dare say that since you're talking serious performance your choises are Zilla 2kA versus Soliton (I haven't seen any claims about Netgain so I really can't give you any hints about that one), the Zilla 2kA definitely wins on peak current but according to the specs it might eventually drop down to 600 Amps. For drag racing this is obviously not a problem but, again, seconds versus minutes. I can't really tell you which one's the better one for you because that depends on how long the Zilla will stay above 1kA, how much current you really need and for how long.

Now; motor. With those performance numbers I'm afraid you'll blow up the TransWarP. It will be too much Volt and too much current for too long. You probably want a siamese build since that cuts the power per motor in half which will drastically increase the chance that you make it to the end. You might also want to consider forced cooling too, ESPECIALLY if you go direct drive, since the motors won't get much air flow at all at low rpm's but you'll still force a LOT of current through the motor and thus generating insane amount of heat. If you want to go with the high voltage version or not I'm not competent to tell you, I'd say Major is the guy that can give you that answer. With a siamese the Zilla has an edge since it can do series/parallel shift. It's on the todo-list for the Soliton (and Netgain I think?) as well, but there's no ETA for when...

Finally, transmission. I think direct drive is a bad idea all considered, because you probably want to keep the RPM high to be as nice as possible to the motor(s) and that means you'll have to keep the gear box. Since you probably don't want to wait a second or two when changing gears you probably also want to keep the clutch. But now's the question, can your transmission handle the torque? Pushing 1kA through one motor will give you a torque in the 200 Ft/Lbs-range, using a siamese setup in serial mode will mean 400 and increasing it to 2kA in serial mode will be somewhere in the 800-range! When will the transmission (or it's mountings) snap?

One thing's for sure, you better have a big wallet.

[toddshotrods]

There are so many things to address here I didn't even try quoting, because the quotes would dominate my whole post. I'll try to just address subject matters, instead of exact wording or posts.

Autocross
I am building an autocroser as well, and also plan to sprint down the drag strip. What kind of autocross are you running in that lasts 5 minutes! That seems like an awfully l-o-n-g time for an autocross race, and more like a short road course. The autocross races I watched at the local Goodguys car show here in Columbus were completed in less than 30 seconds by the fastest cars, and still under a minute by the slower ones.

The biggest point with this subject, in your case, is weight. Even a stripped down unibody car is going to be too heavy to effectively compete in an autocross race without a transmission - or - rear end gearing that is too steep to do anything more than city driving. Those gears may also come back to bite you in the autocross because it won't want to stretch out on the final straight. You will punish your motor and batteries running direct drive, because off the apex of every turn you're going to be asking them for max current to make up for not having enough gearing.

My project, by comparison, is being scratch-built and purposely designed to run direct drive. I am shooting for a final weight of 1200lbs with A123s. I am also using an 11-inch motor, which is capable of a ridiculous amount of torque for a 1200lb vehicle. The goal is that I won't be stressing the motor and batteries so much off the apex because it will actually have more torque than I can succesfully apply. The vehicle is also a dedicated race and show car, with no real-world expectations other than an occasional trip up the street for fun. That allows me to (hopefully) afford A123s. It looks like my pack will be around $15K, and under 500lbs.

I don't mean to go on about my project. I am trying to give you an idea of how the project was planned. Unless we are missing critical details, your plans seems to be a mix of components and ideas that will likely result in disappointment. You have a production street car that you plan to convert to an EV racer/driver, with a mild performance-oriented powertrain combination. It sounds like you will ultimately break a lot of parts, and eventually kill the motor and/or battery pack. Shoving enough current through to repeatedly accelerate the steel-bodied car will stress the batteries and motor, and the high torque loads delivered electric motor style (instantaneously - like a hit of nitrous oxide) will stress the driveshaft and rear end.

Transmission
As noted, running direct drive with a relatively heavy vehicle is probably asking too much from your motor and batteries - in an autocross race environment. If you were just drag racing you could manage it. The converted Powerglide (do a search here) might be a nice option if you don't want to shift, and want a more futuristic "feel". They can be built to withstand over 1200lb-ft of torque and live to tell about it. There are also a number of racing manuals that can handle high-torque racing applications. When I was considering using a transmission, one thing I found appealing is that you can use dog-engagement race transmissions that can be shifted without a clutch. Because an EV can simply select the appropriate gear from a standing start and accelerate without use of the clutch it opens the door for using these transmissions. Whatever route you plan to go, if you choose to use a transmission, be prepared to pay the piper. You need a really stout transmission race transmission because the street models aren't designed to handle the repeated shock of instantaneous torque hits. The phrase "nitrous-ready" is a good thing for an EV racer's parts.

Controller
I'm not pitching for anyone - yet - but have a couple favorites. I have been enamored with Zillas since I first learned about EV drag racing, and then along came a spider named Soliton. I like the Zilla's track record and relentless ability to slam as much current as your batteries can muster up on the motor. I like the Soliton's hi-tech build and ability to deliver whopping doses of current until someone screams "Uncle!" I am split between which one makes the most sense in an autocross race. Until there's a 2K Soliton, the Zilla will win likely continue to dominate at the drag strip, but autocross is a different animal. It's unproven whether one could even get 2K amps into the motor and on the ground, and you're definitely not going to use any substantial amount of current continuously. You're on and off the pedal, from apex to entry point. I watched some 500-700hp muscle cars (with road-race suspension underneath) go through the cones at the aforementioned Goodguys event. They struggled to successfully apply the ramp up of torque their ICE powertrains delivered - even with really wide, sticky, rear tires. The ones who got a little overzealous with that application ended up doing nice little 360s. One guy just enjoyed the moment, kept his foot in it for a couple turns, then emerged from a cloud of tire smoke. This would be even more challenging with an e-motor that's capable of full torque whenever you ask for it.

I look forward to that challenge but, as I pointed out, spent a lot of time designing for the intended mission.

[rickeolis]

Hi guys,
This is great input, I really need it.
Ok, so I agree that 5 minute runs are too long in AutoX, maybe 2 is more realistic. Also, I am looking at a 1500 pound car or lighter when done, which is why I opted or the 9" motor. I can move up to the 11" if needed, I thought about it many times...
As for the performance spec's, the Tesla can do a much quicker 0-60 time (3 seconds??) and is capable of 100 miles. As long as I keep the weight down, I think my spec's (0-60 in 5 seconds and 50 miles), is doable. It's a direct drive too.
A tranny, clutch, shifter, pedals, linkage, and related mounting hardware would add hundreds of pounds, and that alone should help me keep the need for enourmous torque down.
A stock 1979 RX7 weighs about 2400 pounds, minus 12a motor at 350 pounds, minus tranny and clutch and linkage (250 pounds), minus gas tank (40), exhaust system (60), radiator and lines (40), A\C unit and heater (70), entire interior (150), steel motor mounts (30), radio and speakers (20), stock lead\acid battery (50), etc. gets me down less than 1300. Then I can cut out lots of unnecessary heat shields, brackets, battery tray, lines and hoses, but I will also get aggressive about certain panels and brackets.
Given all that, I will then add in the new motor and controller and batteries. No idea how much it will weigh realistically, but I can get it weighed. I still think it will be less that 1500...
This is much lighter that Metros and Festivas using lead acid battreries and still doing 8 second 0-60's and up to 65 MPH for 70 miles using 400 amp controllers. I think 1200 amp controllers and lithium batteries should get me where I want. I could be wrong though...

Rick

[Bowser330]

For performance either drag or autoX you will need the following:
(1) High power battery pack (with high C rating) e.g. A123, Kokam, Headway
(2) Dual motor or large single motor e.g. siamese 8/9, Warp11HV, or 13"
(3) High amperage controller e.g. Zilla, Soliton, Netgain
(4) Best donor you can find e.g. weight, handling.

RX7 is not a bad choice, good luck and report back your performance numbers!

[rickeolis]

Thanks Bowser,
I know about the A123s but not the Kokam or Headways. I need to look into that.
Guys, why the high voltage motors over the 144 or 156 volt models?
Thanks again!

Rick

[Bowser330]

Originally Posted by rickeolis

Thanks Bowser,
I know about the A123s but not the Kokam or Headways. I need to look into that.
Guys, why the high voltage motors over the 144 or 156 volt models?
Thanks again!

Rick

Simple answer:

Because John Wayland's and Dennis Berube's dragsters have high voltage.

Complex answer:

Higher voltage allows for more amps to be drawn at higher rpms. example: 144V will allow 500A to be pulled up until 2000rpm and 288V will allow 500A to be pulled up till 4000rpm... if 500A to a motor is 150ftlbs, then which would you rather have?....

150ftlbs @ 2000rpm = 57hp
or...
150ftlbs @ 4000rpm = 114hp

So lets say you wanted to build a 320V pack that can pulse at 2000A peak

1500 Headway cells will cost about 26K$USD for 320V 150A (15C pulse)
13.33C = 2000A peak
It will also weigh 1013 lbs for the pack

320V*150AH = 48kwh
if your lightweight, aerodynamic car, got 250wh/mile then 48kwh = 192mile range (100% DoD)

[Qer]

Just an addition to Bowsers post:

Even if you "only" have a WarP 9" that will probably zorch if you get close to 200 Volt it still makes sense to have a higher pack voltage since this means sagging will have a lesser impact. Pulling hundreds of amps out of a pack will make the voltage drop pretty drastically and if you don't have a margin that means your top rpm will suffer.