# Direct drive Warp 9 or warp 11



## JRP3 (Mar 7, 2008)

They can both run at 192 volts and possibly higher. I believe RPMs increase in proportion, i.e. 3000rpm at 72 volts would be 6000 at 144 volts, but there may be a drop off near max voltage, since I don't think a warp 9 will turn 11000 rpm at 144 if it does 5500 at 72.


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## paker (Jun 20, 2008)

I've also been wondering about direct drive. I found this on the EV Discussion List.


On 25/01/2008, at 9:34 AM, Gerald Wagner wrote: 

> Hello all, I have purchased a 1986 Mazda RX-7 for conversion. It is 
> totally stripped , restored, and painted. The engine and trans were 
> sold 
> off. My plan is to install a TransWarP *11* *inch* *motor* directly to 
> the rear 
> differential using the Mazda drive shaft. 
> 
> The curb weight of the original car was 2700 lbs. I believe I can 
> stay 
> within that weight if I can get LiFeP04 batteries. The car will be 
> used as 
> a daily driver and probably for SCCA solo autocross events. 
> 
> The question is will the *11* *inch* *motor* handle the starting loads? 
> The diff 
> is a 4.*11* limited slip IRS stock unit. The tires measure 24 *inches* 
> diameter. I calculate a top speed of 87 MPH at 5000 rpm. 500 rpm 
> shows 
> about 9 mph and 4000 equals 70 mph. 2000 to 3000 will cover most all 
> of my 
> city driving. I will use a Zilla 1K LV control, most likely at 144 
> volts. 
> 
> Anybody have experience with the *11* Netgain *motors*? Are there temp 
> problems 
> at low speeds? Any other problems I might encounter? 
> 
> Jerry Wagner ( BTW all driving will be in central Florida, ie. no 
> hills) 


Hi Jerry, 

Thought I'd pipe up because it sounds very similar to my project 
(Miata / LiFePO4 / Warp11 direct drive). 

The main catch with direct drive is that you can't keep the *motor* in 
its optimal efficiency band, which is at about 2000rpm. You'll notice 
2000rpm equates to 35mph, so for suburban cruising it's almost ideal 
(and avoids gearbox losses), but if you're likely to climb a lot of 
long steep hills at 10mph.. keep the gearbox! 

Torque first of all, its plenty of *motor* for direct drive but if you 
plan to use it on the racetrack, a little more current from your 
controller would be a plus. At 1000 amps (the peak for a Z1K) you'll 
get a little over 400 Nm of torque from a WarP *11*, which is about 
*half* the peak torque of a 13B turbo engine running through the 
gearbox in first gear. (The 13B turbo engine in your RX7 had about 
250Nm of torque peak. In first gear through a gearbox, that's 
something like 800Nm of torque to the diff.) So, having 2000 amps on 
tap would be more fun. 

Then you have the problem of finding a battery which can deliver 2000 
amps! Sometimes it's easier to just run a higher voltage pack and let 
the *motor* controller do its magic to increase the current. 

Unfortunately both of those things are pointing towards a much more 
expensive Z2K-HV controller and higher voltage pack! But, you might 
want to do the same thing as me and live with average performance from 
a 1000A controller and modest battery pack until you can afford 
better 

Kind regards, 

Ian Hooper 
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