# Motor selection for '69 VW Bug (AC)



## corbin (Apr 6, 2010)

Howdy!
I'm trying to decide on what motor/controller to get for my bug. I'm leaning strongly towards an AC system (my reasons of AC vs DC on my blog).

My main goals: 65-70 mph on the freeway, and 55mph up a ~5% grade hill for 7 miles (roughly 6 minutes of climbing). I'm calculating 38kw to maintain 55 mph up this grade. 

See my post on "EV AC Drive Motor selection" for the long details of the motors I've found. My choices seem to be: MES-DEA 20-330 (40kW cont), Azure Dynamics AC55 (25kW cont), Thunderstruck AC50 (50hp = 37kW, I think that is continuous?), Electro Vehicles Europe (EVE) M2-AC30L (30kw).

I'm considering the MES-DEA 200-330 (40kW continuous). What do people think about this choice? 

Has anyone in the US ordered from EVE in Italy? If so, did it work out well? Did you have to pay customs fees, and if so, about what was the rate?

EVE seems to have better prices than MetricMind, but I do like that MetricMind is on the west coast of the USA (close by me in CA). 

I'm also considering the Azure Dynamics AC55, but it is only 25 kW cont and 59kW peak. I'm worried that my hill would generate to much heat for that motor. The advantage is the system as a hole is cheaper. The EVE M2-AC30L might be better, but I'm not sure if I can get it from Italy.

Does Electro Vehicles Europe (EVE) offer a 40 or 50 kw version of their motor? Anyone have it?

A lot of questions, but I appreciate any input. Nothing is set in stone yet, and I'm still learning a TON about EV's. Thanks!

Corbin


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## Olaf-Lampe (Feb 24, 2010)

I have no practical experience with any of the motors, we always used Siemens motors.
My idea is, that the AC55 is way underrated but a bit heavy.
The AC50-combo suffers from the low voltage curtis controller.
The MES-DEA is a good choice, because it is watercooled and comes with a matching controller.
My favorite is the M2-AC30L from EVE. It's also watercooled and cheaper. If folks from EVE can guarantee it's working with the TIM600W you'll fly up this hill. 
My major concern is the gearbox and the huge peak torque all of these motors can generate. Will you use the standard gearbox or use an upgrade from Porsche 914 or VW transporters?

Good luck
Olaf
www.thorr.eu


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## corbin (Apr 6, 2010)

Olaf-Lampe said:


> I have no practical experience with any of the motors, we always used Siemens motors.
> My idea is, that the AC55 is way underrated but a bit heavy.
> The AC50-combo suffers from the low voltage curtis controller.
> The MES-DEA is a good choice, because it is watercooled and comes with a matching controller.
> ...


Hi Olaf,
I was currently planning on using the stock transmission, but I may look into the VW transporter or Porsche 914 one. 

thanks for the info and advice!

--corbin


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## tomofreno (Mar 3, 2009)

I am using an AC50 in a Suzuki Swift (SwiftE thread under Conversions), which is similar in weight and drag to a VW bug. It might meet your performance requirements, but you would be pushing it. The max voltage of the controller is 130V not 108. I am running it at 115 nominal (36 cells at 3.2V per cell). The main issue is overheating, mainly of the controller. I recently added a heat sink to my controller, and now it runs at about 25 C or so above ambient at 65 mph on level ground, pulling about 165A. You would likely pull around 280A up a 5% grade at 55 mph, so the controller would get quite a bit hotter, likely fairly close to the 85C limit of the controller. The motor itself does not get as hot and has a 120C max temp. 

The EVE motor looks considerably better to me with its much higher constant power rating, as well as higher peak power (I get about 49 kW peak shaft power with 115V). Seems it and the MES 400 controller would work well for you. I don't think you would use as high as 280A rms with a 288V system. This combo looks like better performance for the price compared to the AC50/Curtis.

You may have difficulty finding space for 90+ cells to get over 288V in a VW. You will also need space for a suitable size liquid-air heat exchanger (radiator) in good airflow or with a fan to cool the water for the controller and motor.


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## corbin (Apr 6, 2010)

tomofreno said:


> I am using an AC50 in a Suzuki Swift (SwiftE thread under Conversions), which is similar in weight and drag to a VW bug. It might meet your performance requirements, but you would be pushing it. The max voltage of the controller is 130V not 108. I am running it at 115 nominal (36 cells at 3.2V per cell). The main issue is overheating, mainly of the controller. I recently added a heat sink to my controller, and now it runs at about 25 C or so above ambient at 65 mph on level ground, pulling about 165A. You would likely pull around 280A up a 5% grade at 55 mph, so the controller would get quite a bit hotter, likely fairly close to the 85C limit of the controller. The motor itself does not get as hot and has a 120C max temp.
> 
> The EVE motor looks considerably better to me with its much higher constant power rating, as well as higher peak power (I get about 49 kW peak shaft power with 115V). Seems it and the MES 400 controller would work well for you. I don't think you would use as high as 280A rms with a 288V system. This combo looks like better performance for the price compared to the AC50/Curtis.
> 
> You may have difficulty finding space for 90+ cells to get over 288V in a VW. You will also need space for a suitable size liquid-air heat exchanger (radiator) in good airflow or with a fan to cool the water for the controller and motor.


Hi Tom, Thanks for the info! Your conversion is one of the ones I bookmarked, as I really like the way it came together. 

I do want a little more "umph" power than what the AC50 gives, so it sounds like I should investigate the EVE. I contacted them, and they are looking into what they think would work best for my system. They apparently put together a nice controller/motor combo that suites the customers needs, so I'll see what they have to say.

-corbin


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## tomofreno (Mar 3, 2009)

I estimate ("evcalculator" spreadsheet at electricnevada.org) about 35 HP or 26 kW at the wheels to move the Swift up a 5% grade at 55 mph. Dividing by the combined efficiency of the AC50/Curtis controller of about 0.8 gives about 33 kW from the cells. My pack would likely sag to about 112V if near full charge, so about 295 A would be required, or about 1.64C (180 Ah cells).

I have run the Swift at 165 A for about 14 miles and motor and controller temps got to 41 and 43 C respectively and remained there, in a 17 C ambient. So at an ambient of about 38 C (100 F) the controller might get to around 64 C. At 295 A I think it might be pushing the 85 C limit of the controller, but the motor should be ok since its limit is 120 C. Note that is about 165 A * 114V = 18 kW, so motor output might have been around 80% of that or about 15 kW, or 20 HP, so the 15 HP rating is conservative. I also regularly run it at 250 A up hills at 50 - 55 mph, but only about 2 to 3 miles, with no overheating issues. 

If you are going to drive that hill every day I would suggest keeping the current at 1.5C or below to prolong cell life (wide disagreement on this I expect, but that is what I would do). So 200 Ah cells would be better. If you go with something like the EVE motor with a 288V (minimum I would guess) pack, you would likely require around 115 A (cell) current for 33 kW, so you could likely use 90 Ah cells (I think cells jump from 60 Ah to 90 Ah, 100 Ah...). Of course you will require a lot of them to get the 288V including sag. I would carefully measure a VW to ensure you can fit the number of 200 Ah or 90 Ah cells required for your range and voltage requirements. 

A couple other comments. I usually use about 200 to 205 Wh/mile, not 300 as some typically assume. If you look at the above referenced spreadsheet you can compare the AC50 with the Azure 24LS (using higher voltage pack). What I found for my car, gearing, and voltage, is the Azure 24LS, wye connected, is significantly weaker than the AC50 at lower speeds (64 ft lb versus 90 ft lb max torque), similar at around 50 to 65 mph, and a bit stronger at higher speeds, at about 70 mph and above. It is weaker delta connected, and the Azure 24 is weaker still. That is from published specs. I don't know about temperature control of the 24LS.

The EVE specs look better to me.


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## corbin (Apr 6, 2010)

tomofreno said:


> I estimate ("evcalculator" spreadsheet at electricnevada.org) about 35 HP or 26 kW at the wheels to move the Swift up a 5% grade at 55 mph. Dividing by the combined efficiency of the AC50/Curtis controller of about 0.8 gives about 33 kW from the cells. My pack would likely sag to about 112V if near full charge, so about 295 A would be required, or about 1.64C (180 Ah cells).


 Tomofreno -- this information is invaluable to me! The swift is pretty darn close to the bug weight. It looks like the AC50 actually might suite my needs, especially with 200ah batteries. I'm still waiting to hear back from EVE, but I have a feeling that that motor/controller combo will cost quite a bit more than the AC50.

At this point, my main considerations are the AC50 vs the Warp9 (or possibly the Warp11, if I could fit it in). 

If I run the Warp 9 at 156v I believe it will put out about 35kw of power -- nearly the same as the AC50, unless I'm missing something. If that's the case, then I probably would want to go with the AC50.

corbin


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## tomofreno (Mar 3, 2009)

The Warp9 is similar to the Advanced DC Motors FB1-4001 9" motor as far as power and torque - it has larger brushes and other things to make it more robust - but otherwise they are very similar. The FB1-4001 is also in the spreadsheet, so you can compare it also. Just enter 45 for the "number of batteries" input variable (green fields) for a 144V pack (it won't do 156V as I didn't set it up with a torque -speed curve for that high of voltage). Scroll down to line 605 to see results for a Curtis max 500A controller, and line 705 for a Kelly 750A controller. Make of controller doesn't matter, all the spreadsheet uses is the max current of the controller to estimate max torque. 

Available wheel torque at 50 mph with the AC50/Curtis and 115V pack is about 393 ft-lb in 3rd gear. It is 336 ft-lb for the FB1-4001/144V pack/Curtis 500A controller in 4th gear (torque falls off faster with rpm for the DC motor so a higher gear gives more wheel torque), and 607 ft-lb for the FB1-4001 and Kelly 750A controller. A Zilla 1k or Soliton1 would do better yet with 1000A. The 9" DC motor with a high current controller is much more powerful. A bug would scream with such a powerful motor/controller combination. Someone in our local ev club has a Ford Festiva with a Warp9, 156V sla pack, and Zilla 1k. It does 0 to 60 in 8 seconds, and would do better if he could keep the tires from spinning.

Edit: I guess I should have pointed out that using a high current controller would require at least 200Ah cells - 3C would give you 600A max. Fitting 45 of these in a VW would be a real challenge. Spend some time studying/measuring, look at the trade-offs.


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## corbin (Apr 6, 2010)

tomofreno said:


> ...
> Available wheel torque at 50 mph with the AC50/Curtis and 115V pack is about 393 ft-lb in 3rd gear. It is 336 ft-lb for the FB1-4001/144V pack/Curtis 500A controller in 4th gear (torque falls off faster with rpm for the DC motor so a higher gear gives more wheel torque), and 607 ft-lb for the FB1-4001 and Kelly 750A controller. A Zilla 1k or Soliton1 would do better yet with 1000A. The 9" DC motor with a high current controller is much more powerful. A bug would scream with such a powerful motor/controller combination. Someone in our local ev club has a Ford Festiva with a Warp9, 156V sla pack, and Zilla 1k. It does 0 to 60 in 8 seconds, and would do better if he could keep the tires from spinning.
> 
> Edit: I guess I should have pointed out that using a high current controller would require at least 200Ah cells - 3C would give you 600A max. Fitting 45 of these in a VW would be a real challenge. Spend some time studying/measuring, look at the trade-offs.


Awesome -- that is pretty much the conclusion I was coming to -- Warp9 with 45+ 200ah batteries (provided I can fit em in!). I've been email chatting with Travis (who has '66 Bug) and that was one of his recommendations. The only concern might be how long I have to run at high power to climb my hill. I'll play with some of the numbers in the spreadsheet and see what I find out. Is the "EV_calculator_rev5.09" spreadsheet made by you? It is a great piece of work -- thanks for sharing it! 

Edit: In the end, I might have to give up my back seat space in order to fit the batteries. But it is more important for me to be able to make it home than to take passengers!

-corbin


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## tomofreno (Mar 3, 2009)

> It is a great piece of work -- thanks for sharing it!


 Yes, thanks. I made it up to decide what to use for my conversion. Of course that decision will depend on what a person wants, and her/his biases. I was interested in efficiency and low energy use since I power the car and house with solar PV, and like to minimize my impact. I also wanted enough pep to make it fun to drive and easily accelerate to highway speeds, but didn't care if it had sports car acceleration. That is what led to my choice. Others have different goals. Yesterday I was following some friends in an ICE going up about a 2 mile 6% grade. Speed limit is 50, but they were going 45. To show them an electric car was not necessarily slow, I passed them and accelerated to about 58 mph by the time my rear bumper was about 2 car lengths past their front one. I didn't floor it so it could do better. I continued up the hill for another mile at about 55 mph and the controller reached 45C (21C outside temp), motor reached 43 C. Of course a 9" DC motor/high current controller would do much better...depends what you want.


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## Bowser330 (Jun 15, 2008)

tomofreno said:


> ..... Someone in our local ev club has a Ford Festiva with a Warp9, 156V sla pack, and Zilla 1k. It does 0 to 60 in 8 seconds, and would do better if he could keep the tires from spinning....


This has got me thinking, since the motor is electronically controlled (controller) couldn't we integrate a traction assist function that would learn how many amps could be effeciently yet powerfully used at any rpm...(it could notice wheel slip and then learn to reduce amps(torque) until traction is attained...

That way the launch without the spinning would be more stable, faster, more efficienct way of energy use...


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## corbin (Apr 6, 2010)

Hi Tom -- I'm wondering if you can give me some more advice on AC motors, especially given your real world experience with the Swift, and driving it around with some hills. I also am interested to hear from anyone else who has input.

I'm trying to decide on which motor to go for: 
EVE's AC30
EVE's AC40
Or, a DC option: Netgain WarP 9

Here's a chart comparing some of the Torque values from the manufactures. The WarP 9 (gray) seems to actually have the lowest torque value, which surprises me as I thought it should have more torque than the HPGC AC50. 










Now, the max torque for the EVE AC30 (yellow) is 150lb-ft (200Nm) and it puts out 30Kw continuous. I calculated that my bug needs at least 33Kw of power to go up my 5% gradient hill for 7 minutes -- do you think it would be pushing it too long to go up my hill? Do you think it would have decent feeling acceleration? 

It is also interesting that the WarP 9's nominal torque is quite low; is that something I should be concerned with for hill climbing?

I *know* the EVE AC40 would be powerful enough, but it will probably cost me $1-$2k more than the EVE AC30.

Thanks!
corbin

Also, for reference, this is also on my blog:
http://www.corbinstreehouse.com/blog/2010/05/plug-bug-more-motor-comparisions/


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## Tesseract (Sep 27, 2008)

corbin said:


> ...The WarP 9 (gray) seems to actually have the lowest torque value, which surprises me as I thought it should have more torque than the HPGC AC50.


Well, the torque from any motor depends on how many amps you feed it. For the WarP 9 you selected the value for torque from the manufacturer's chart at 334.5A. Feed it 1000A and you'll get somewhere around 210ft-lbs of torque.

Also, as a sanity check you should plug in the RPM and torque (ft-lbs) to the familiar formula:

hp = (torque * rpm)/5252

and make sure you don't come up with something crazy.

For example, from the WarP 9 chart it says that with 334.5A at 72V the motor delivers 70 ft-lbs at 2158 rpm. Input power is 24.1kW (32.3hp) while output power is 28.7hp... In this case, output power is 89% of input power which is sane, if a tad optimistic (85% would be expected at this current level).

Your AC40 chart (60s) indicates 208ft-lbs at 2000rpm, which is 79.2hp. I don't know if this is realistic or not because I could not find an "AC40" system at EVE.


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## corbin (Apr 6, 2010)

Hi Jeffrey,



Tesseract said:


> Well, the torque from any motor depends on how many amps you feed it. For the WarP 9 you selected the value for torque from the manufacturer's chart at 334.5A. Feed it 1000A and you'll get somewhere around 210ft-lbs of torque.


As far as I can tell, torque seems exponential to amps -- but I can't find any definitive equation to relate the two for a particular motor, and how long I can run at higher than nominal amps (and, exactly what nominal amps is for the WarP 9 -- I think it is about 250 amps based on research). Is there any source for how I can compute these things?




Tesseract said:


> Also, as a sanity check you should plug in the RPM and torque (ft-lbs) to the familiar formula:


Thanks! I've been doing this too (I left it off for simplicity). Part of the problem I have been having is that the EVE motor graphs don't indicate the amps they are pumping in, so I can't calculate efficiency. 

Is there any way I can do a best guess for amp input with AC motors?



Tesseract said:


> Your AC40 chart (60s) indicates 208ft-lbs at 2000rpm, which is 79.2hp. I don't know if this is realistic or not because I could not find an "AC40" system at EVE.


They emailed me their graph for the AC40; it is here:

http://www.corbinstreehouse.com/misc/M3-ac40_L.pdf

Price: 2780 euro (with VAT) = ~$3500 US -- maybe 10% less if they drop the VAT, but importing might cost that amount anyways. They pair it with the MES-DEA TIM400 (~$3,000 US) for a total of about $6500 for the motor/controller combo. Still pricey compared to a WarP9 ($1700) + Soliton 1 ($3k) = $4700 total. I'm still pondering if regen worth $1800 bucks to me (with my hills). If my commute was flat, I'd go DC all the way, but with AC so close in price I'm considering it..

Thanks again for the help -- I'm slowly learning all this stuff and becoming more educated as the days roll on.

--corbin


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## corbin (Apr 6, 2010)

Looks like I found one answer here:
http://www.belktronix.com/WarPOwnersManual.pdf

"They are actually rated at 450 Amps for 5 minutes, 225 Amps for 1 hour, and 190 Amps continuous duty"

As a guess, I could probably safely run the WarP9 at 300 amps for 10 minutes. The raw computation with a 156v pack would be 46.8Kw (ignoring efficiencies) -- definitely enough to make it up my hill and not overheat the motor.

corbin


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## tomofreno (Mar 3, 2009)

> Hi Tom -- I'm wondering if you can give me some more advice on AC motors


I thought you decided to go with a WarP9? The EVE AC30 with the Mes-Dea 400W controller would power a bug very well, and an AC40 with the 600W controller would do better, but not as well as a Warp9 and Zilla controller. As Tesseract pointed out, you plotted torque for the Warp9 with a fairly low current, the Zilla 1k or Soliton1 will give much more current. The EVE motors do have quite high continuous ratings though, likely because they are water cooled - but you will need a good radiator to dissipate that heat.

It depends on what you want. I don't like brush and commutator wear. I like induction. I like braking with the accelerator and recouping some of the vehicle kinetic energy into the batteries, because I like efficiency. And I like minimizing addition of heavy metals and other contamination from brake wear to street runoff into streams. I like only one moving part on two sealed bearings. Regen will extend range, but not a lot, maybe 10% or a bit more if you have hills and/or lots of stops. These are not only dollar and cents considerations. Depends on what you want. Some want to accelerate from 0 to 60 in under 8 seconds, or go fast up a 10% grade. A series DC motor/high current controller is better for them. Make a list of the features you desire, and prioritize them. You will pay more for AC no doubt. You have to decide if it is worth it to you. Don't worry TOO much about the continuous ratings of the motors. You can add a blower to a Warp9 or other air-cooled motor and increase its continuous power significantly. I have run the "15 HP" AC50 at a bit over 20 HP for 10 -15 minutes or so a couple times with no problem, no blower. Temperature clamps at about 40C. You likely would be pushing the Curtis controller on that hill on a hot summer day though, whereas the AC30 or 40 and Mes-Dea 400 or 600 would handle it easily. Service/support is another issue since the EVE is from Italy. I would see if I could find any users of those motors, or ask crodriver and others in Europe if they know anything about them.


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## Tesseract (Sep 27, 2008)

corbin said:


> As far as I can tell, torque seems exponential to amps -- but I can't find any definitive equation to relate the two for a particular motor, and how long I can run at higher than nominal amps (and, exactly what nominal amps is for the WarP 9 -- I think it is about 250 amps based on research). Is there any source for how I can compute these things?


Torque is proportional to the square of current at low to moderate currents, but once the stator (field) enters into saturation appreciably the relationship turns to a linear one. 

Your second issue - how long can you run a motor at a particular current - has too many variables to answer definitively. Some like to see what is called the "S2-60" rating for the motor, which is the current that can be tolerated for 60 minutes. Unless your EV has enough range to drive continuously for 60 minutes, though, this results in an unnecessarily conservative number. 

Note that NEMA rates AC induction motors in standard frame sizes with an i²t figure. Thus, doubling the current more or less cuts the allowed time to 1/4th. You may notice that the NetGain numbers do not seem to follow this rule (but they should, as i²t is a physical relationship between power and time that everything in electronics obeys).

At the upper end of the current range DC motors are not restricted so much by heat (i²t) as by commutation failure (resulting in flashover or "zorching").



corbin said:


> Is there any way I can do a best guess for amp input with AC motors?
> ...
> They emailed me their graph for the AC40...


If you know voltage, frequency, RPM, power, and efficiency at at least one operating point, then yes. If you are missing any of the data points, then no.

That data table is just about useless, but I think it is interesting to see that the stall torque rating is little different from that at 1000rpm. That implies the inverter either does not use a terribly sophisticated vector control algorithm or it can not deliver enough current to fully utilize the motor. In general, neither prospect is good for an EV but this is purely conjecture on my part from rather scant data and, of course, I am hardly unbiased 




corbin said:


> ...I'm still pondering if regen worth $1800 bucks to me (with my hills). If my commute was flat, I'd go DC all the way, but with AC so close in price I'm considering it..


Well, Corbin, my take - not dissimilar from Tomofreno's - is that pretty much can not justify regen on a purely economic basis. Does regen save wear on brakes? Sure, but brake pads last an awful long time as it is (my '07 truck with 60k miles, which I bought new, is on its original set). Does it boost range? Sure, but how much is highly dependent on driving style and terrain. It sounds like you would get enough of a benefit from regen to strongly consider it, but, whether it will ever pay for itself (compared to, say, adding a couple extra cells to your pack (assuming, of course, you can fit them in!)) is another question entirely.


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## fugdabug (Jul 14, 2008)

corbin said:


> Awesome -- that is pretty much the conclusion I was coming to -- Warp9 with 45+ 200ah batteries (provided I can fit em in!). I've been email chatting with Travis (who has '66 Bug) and that was one of his recommendations. The only concern might be how long I have to run at high power to climb my hill. I'll play with some of the numbers in the spreadsheet and see what I find out. Is the "EV_calculator_rev5.09" spreadsheet made by you? It is a great piece of work -- thanks for sharing it!
> 
> Edit: In the end, I might have to give up my back seat space in order to fit the batteries. But it is more important for me to be able to make it home than to take passengers!
> 
> -corbin


I guess from my point of view, a warp9 would be a LOT of weight, as well as yourself, and the battery pack etc. in a bug crawing up a 7 mile incline...???
I used a LA pack of 18batteries (1080 lbs...) in a Toyota Corolla Stationwagon... oh it does 45 miles an hour for about 10 miles... then the weight kicks in I get down to 10 mph on a steep hill and if I have gone more than 10 miles the motor is hot enough to fry and egg on it... (I have a D&D ES-31B, DC...) but with AC I would think unless you are an owner of the most amazing bug on the planet made of titanium alloy... rethink the weight issue! Save yourself a lot of expense for little gain.


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## corbin (Apr 6, 2010)

tomofreno said:


> I thought you decided to go with a WarP9? ...


I'm still wishy-washy on making a decision  I'm really leaning towards the DC option, but the people from EVE did get back to me, and their costs aren't that bad, so it made me start to consider it again and want to compare the options.



tomofreno said:


> Service/support is another issue since the EVE is from Italy.


Yes -- this could be an issue, especially since this is my first conversion, and I'm sure I'm going to have lots of questions along the way.

Thanks again for the help and information -- I'll definitely compare the WarP 9 at a higher amp rating, and not worry about it too much.

--corbin


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## corbin (Apr 6, 2010)

Tesseract said:


> If you know voltage, frequency, RPM, power, and efficiency at at least one operating point, then yes. If you are missing any of the data points, then no.


Ah -- interesting; I should see if I can get more data from EVE about their motors. 

Thanks for the info -- I'll take this back home tonight and mull things over more. I'm hoping to run some more numbers on my costs/options/budget (roughly $20k) and make some decisions and purchases this week.

--corbin


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## Bowser330 (Jun 15, 2008)

Rebirth auto used to have some videos on youtube with their converted classic Bug...I think it had a 9" motor, soliton-1, agm batteries...

Like tesseract said before, 1000A is 210ftlbs of torque output...

My car in 5th gear @ 2000rpm goes about 70mph, so 210ftlbs @ 2000rpm = 80hp


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## JRoque (Mar 9, 2010)

Hi. My 2 cents on regen: I think that saying regen "extends range" is a bit of a misnomer that tends to be confusing sometimes. Regen recovers a bit of power back in cases where it would have been wasted to braking. Also, IMHO, you will always get better range if you allow your car to coast instead of regenerating on deceleration. If your car has enough speed to coast for 100', no amount of recovered/regened power from that speed will get you to also travel 100'. It's always best to coast and regen when you must brake. If you brake a lot in your hilly area, regen can certainly help.

Have you considered AC industrial motors? I have no experience with this yet in an actual car but I found it to be cheap enough to try. I picked up a 25 HP AC induction motor on eBay for <$500 shipped. It's a class F insulation (300 deg F), inverter rated (2,500V), ~180lbs, 3 phase, 91% efficient motor. The controller, undersized at the moment, should be around <$500 as well when I'm done with it. Even if I had to buy a controller, it wouldn't be much more than $2K or so. 

I'm targeting ~300V bus voltage which will help to minimize system losses but will also drive the motor way past it's 25 HP rating. The Australia EV guys are doing this by rewiring their motors to a lower voltage while driving it with a much higher voltage. Luckily for us here in US we get dual voltage motors that can then be overdriven to higher peak performance. I'm guessing that most EV motor makers rely on this factor when building their spec sheets. 

JR


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## tomofreno (Mar 3, 2009)

> I think that saying regen "extends range" is a bit of a misnomer that tends to be confusing sometimes. Regen recovers a bit of power back in cases where it would have been wasted to braking.


 Yes, and the result is the same. You use energy (charge at some potential) stored in the batteries per unit time (power out) to accelerate the car. When you apply regen you use some of the kinetic energy of the car to regen energy back into the batteries per unit time (power back in). The net energy you have to move the car is the initial energy stored in the battery plus the energy regen adds to it. So more energy than the initial stored energy, and more range. Given open roads with no traffic, no stop signs, stop lights, sharp bends, or speed limits, I agree you can't do any better than accelerating to some velocity and coasting until you stop. But of course that is not how we drive. If you have to stop, slow down, or stay within the speed limit on a hill, it is more efficient to do so using some of the kinetic energy of the car to put energy back into the batteries rather dissipate it as heat. You always have the option to coast with regen, just ease the throttle up enough to have zero current.


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## tomofreno (Mar 3, 2009)

The life cycle spec for the cells does not specify the current, but it is more likely the "standard" charge/discharge current which is 0.5C, or 100A for 200Ah cells, rather than the maximum continuous discharge current of 3C. If so, repeated, sustained use of currents larger than this will likely degrade cycle life. Something to keep in mind when you select cell size (Ah), pack voltage, and motor/controller, since you will be pulling that long hill each day on the way to work.


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## corbin (Apr 6, 2010)

JRoque said:


> Have you considered AC industrial motors?
> 
> JR


Hi JR,
Yes, I thought about it -- I don't think I have enough motor experience to go this route. Maybe some day I can! Even using the MES-DEA controller might be too difficult for me with my current experience. I've read their manual, but it leaves lots of questions on how to actually implement things.

--corbin


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## corbin (Apr 6, 2010)

tomofreno said:


> The life cycle spec for the cells does not specify the current, but it is more likely the "standard" charge/discharge current which is 0.5C, or 100A for 200Ah cells, rather than the maximum continuous discharge current of 3C. If so, repeated, sustained use of currents larger than this will likely degrade cycle life. Something to keep in mind when you select cell size (Ah), pack voltage, and motor/controller, since you will be pulling that long hill each day on the way to work.


Tom -- thanks again for the advice and info. I really like the idea of using an AC motor, but I think I may end up choosing DC. The availability, and support for all the 'off the shelf' DC systems seems much better than the AC systems available; especially given the price-to-performance ratio. I really want to go with an EVE motor, but I have too many unknowns with the company -- especially since no one else on the forums seems to have experience using them in a conversion.

At this point, I feel quite confident having adequately compared the systems available for my particular performance goals and I'm going to start asking some EV suppliers for price quotes on DC kits.

Thanks again! I'm super excited to actually get my project going...I've spent hours in front of the computer researching for nearly the past month.

-- corbin


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## tomofreno (Mar 3, 2009)

> Even using the MES-DEA controller might be too difficult for me with my current experience.


 Corbin, its sounding like the warp9 might be a better route for you. I think a 5% grade requires around 35 HP or 26 kW energy to the wheels for a vehicle like a bug. Dividing this by motor, controller, and drive train efficiencies gives around 50 HP or 36 kW from the battery pack. I am fairly sure this is asking too much of the Curtis 1238-7501 controller to do for 10 minutes or so in hot weather. It certainly was not designed to do it. It is a nominal 96V, max 550A controller. Also, this controller's max voltage is 130V, which limits you to about a 120V pack max. Then at 36 kW you will have to pull about 300A from the pack, or 1.5C. Not bad, but not as good as the other options as outlined below. You could use a different controller with the AC50 as some suggested, and I think the motor would be fine with a higher current and voltage controller, but it will be something new that no one else has used, so maybe more effort/time for a first conversion, and maybe even an unforseen show stopper. So you can likely leave it out. 

Then you have the EVE AC motors and the warp9. The former happens to have twice the rated voltage you plan to use in the latter. As a result, you would pull about 1 1/4C from 200Ah cells using the warp9 (36kw/144V), and the same from 100Ah cells with the EVE motor. So either would be fairly easy on the battery pack. Both have more than enough power to get you up the hill at the speed you require, and both would have 28.8 kWh packs. Temperature may be more of an issue with the warp9, but you can add a blower if necessary and it should work fine. Others here with warp9s would know if that would be required better than me. Your range might be a bit better with the AC motor/high voltage, but nothing you couldn't offset by adding another couple cells to the pack you use with the warp9 - assuming you require that extra bit of range.

The warp9 is one of the most widely used motors in diy evs, and the Zilla one of the most popular controllers (though I am not sure where you buy a new one these days), so you would have lots of people to answer questions about them, and there is lots of info posted on them on various builder's blogs (I recall a post here showing photos of blower fixturing a guy set up on one for example). As far as I know, no one has experience with the EVE. If documentation and support from the dealer is poor, you will be pretty much on your own. 

You prefer AC and so do I, but the hill constraint drives you to an AC solution that has some additional cost and risk. It is your first conversion. If you want to maximize your chance of an expeditious, successful conversion the warp9 is the way to go. If you are willing to possibly spend lots of time and effort working out possible issues with the EVE, and are less risk averse, then go for the EVE. A conversion with it may not present many problems, or it may be a lot more work. For example you will need to make an adapter plate for it, whereas with the warp9 you can likely just buy one ready made.

Btw, like your blog - and the recumbent unicycle video!


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## corbin (Apr 6, 2010)

Tom -- that's some well said advice, thanks!

I'm already getting addicted to EV conversions, and maybe I can save the AC conversion for a later project 

--corbin


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## Bowser330 (Jun 15, 2008)

corbin said:


> Tom -- that's some well said advice, thanks!
> 
> I'm already getting addicted to EV conversions, and maybe I can save the AC conversion for a later project
> 
> --corbin


thats a very good point corbin, nowhere are you being restricted in converting only one car...another point is you would be able to sell the completed EV beetle to someone looking for less upfront mechanical investment...from what i have heard you can make your money back pretty comfortably...Then turn around and, like you said, use the money to try out an AC conversion...


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## Kelmark (Oct 26, 2009)

tomofreno said:


> Corbin, its sounding like the warp9 might be a better route for you. I think a 5% grade requires around 35 HP or 26 kW energy to the wheels for a vehicle like a bug. Dividing this by motor, controller, and drive train efficiencies gives around 50 HP or 36 kW from the battery pack. I am fairly sure this is asking too much of the Curtis 1238-7501 controller to do for 10 minutes or so in hot weather. It certainly was not designed to do it. It is a nominal 96V, max 550A controller. Also, this controller's max voltage is 130V, which limits you to about a 120V pack max. Then at 36 kW you will have to pull about 300A from the pack, or 1.5C. Not bad, but not as good as the other options as outlined below.
> 
> You prefer AC and so do I, but the hill constraint drives you to an AC solution that has some additional cost and risk. It is your first conversion. If you want to maximize your chance of an expeditious, successful conversion the warp9 is the way to go. If you are willing to possibly spend lots of time and effort working out possible issues with the EVE, and are less risk averse, then go for the EVE. A conversion with it may not present many problems, or it may be a lot more work. For example you will need to make an adapter plate for it, whereas with the warp9 you can likely just buy one ready made.
> 
> Btw, like your blog - and the recumbent unicycle video!


Tom,

I am also looking at switching to DC for my project, due to the cost and availability issues of current AC kits. Although, I am thinking of going with the Warp 11HV instead of pushing 1000+ amps through a warp 9 to get the performance I am looking for.

My question is wouldn’t it be more efficient to use a warp11 or warp11HV instead of a warp9 due to the higher torque to amp ratio on the larger motor? It would also give a greater continues rating for long hills and interstate speeds. If I were to go with the heavier 11" motor I might as well go for the HV to get the larger torque band right? That way I could get the same performance as a warp 9 at 1000 amps out of a warp11HV at 750A.

I know you have a spreadsheet I thought maybe you could look at comparing these three systems on the same platform for available power and efficiency to see if it is worth the extra money.


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## Bowser330 (Jun 15, 2008)

I would vote Warp11-HV with 2000A controller and a pack of 600 (320V/48AH) headway batteries...


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## corbin (Apr 6, 2010)

Kelmark said:


> Tom,
> 
> I am also looking at switching to DC for my project, due to the cost and availability issues of current AC kits. Although, I am thinking of going with the Warp 11HV instead of pushing 1000+ amps through a warp 9 to get the performance I am looking for.
> 
> ...


Kelmark - what kind of car are you converting and what weight is it? Are you looking for a high performance machine, or a commuter?

--corbin


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## Kelmark (Oct 26, 2009)

corbin said:


> Kelmark - what kind of car are you converting and what weight is it? Are you looking for a high performance machine, or a commuter?
> 
> --corbin


The car is a fiberglass kit car called Kelmark GT I added my build link below. The finished weight is probably going to be around 1800 lbs. And will be built for car shows, so looking for street performance, not just racing. It will also be my commuter after a few years of shows.


http://www.diyelectriccar.com/forums/showthread.php/kelmark-gt-solar-series-hybrid-41024.html


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## tomofreno (Mar 3, 2009)

> My question is wouldn’t it be more efficient to use a warp11 or warp11HV instead of a warp9 due to the higher torque to amp ratio on the larger motor? It would also give a greater continues rating for long hills and interstate speeds. If I were to go with the heavier 11" motor I might as well go for the HV to get the larger torque band right?


 Major could answer the efficiency question better than me I think. I don't have torque-speed curves for the 11" motor so didn't put it in my spreadsheet. Seems like gross overkill to me though for an 1800 lb vehicle. What is your goal for 0 to 60 mph time? What is your statement that you require 1000A with a warp9 based on, maxvtol's spreadsheet?


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## Kelmark (Oct 26, 2009)

tomofreno said:


> Major could answer the efficiency question better than me I think. I don't have torque-speed curves for the 11" motor so didn't put it in my spreadsheet. Seems like gross overkill to me though for an 1800 lb vehicle. What is your goal for 0 to 60 mph time? What is your statement that you require 1000A with a warp9 based on, maxvtol's spreadsheet?


 
The Warp 9 at 1000A "237 ft lbs" should be able to do around a 7.5 second 0-60mph. But higher amps are harder on the motor and efficiency. I agree that the 11" is overkill at higher amps I.E. 1400A =415 ft lbs. 

However, the HV has a wider torque curve so if I limit the motor amps to around 600A on the 11HV "148 ft lbs" I should still be able to reach 0-60 time with less power used. Also at cruising speed the 11" motor should use less power than the 9”. 

Warp 9 @300A = 59.3 ft lbs @1000A = 237 ft lbs
Warp 11HV @300A = 74.0 ft lbs @1000A = 291ft lbs

With the Netgain 360V controller, the max draw from the batteries would be 300A @ peak load @ 5500 rpm (peak rpm). Most of the time it would be below 100A.


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## Tesseract (Sep 27, 2008)

An 11" motor with a 1000A (or higher?!) controller in a classic VW bug? Are you people nuts? Look, I can tell you from experience that this is way too much power for the chassis and transaxle.

Of course, who am I to argue with having too much power???

http://www.youtube.com/watch?v=cz069B67gAo&feature=related


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## Kelmark (Oct 26, 2009)

Tesseract said:


> An 11" motor with a 1000A (or higher?!) controller in a classic VW bug? Are you people nuts? Look, I can tell you from experience that this is way too much power for the chassis and transaxle.
> 
> Of course, who am I to argue with having too much power???
> 
> http://www.youtube.com/watch?v=cz069B67gAo&feature=related


I think we all agree 1000+ Amps on a Warp 11 is way too much for a VW drive train. My question is would it be more efficient, in addition to prolonging equipment life, to use a Warp 11 HV at around 600A max versus a Warp 9 at 1000A max with equal performance?


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## JRoque (Mar 9, 2010)

> a Warp 11 HV at around 600A max


IMHO, as long as you don't go over the max volt rating, you'll get better system performance with higher voltage and lower amperage. For the HV, 288V @ 200A for up to an hour seems to work. Or you can burn down a track at up to 2K amps but forget about efficiency and component longevity.

JR


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## Kelmark (Oct 26, 2009)

JRoque said:


> IMHO, as long as you don't go over the max volt rating, you'll get better system performance with higher voltage and lower amperage. For the HV, 288V @ 200A for up to an hour seems to work. Or you can burn down a track at up to 2K amps but forget about efficiency and component longevity.
> 
> JR


I am still planning my first EV so can you explain in more detail? The max motor voltage for the warp 9 is 170V (5500rpm) and the although the 11HV is 288V normally you would limit this motor to around 180V as well the difference is that the HV has doubled the torque band of the Warp11. At least this is how I understand it. The motor voltage will go up and down with rpm right? I think the HV can handle 190 motor Amps all day long. The 600A would be for max acceleration.


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## cruisin (Jun 3, 2009)

You guys are looking for numbers without any experience in reality. I have a 1970 beetle using a Impulse 9 motor, Kelly 800a controller and 117vdc 225ah 4866 Sanyo 18650 Li-ion cells, and use 2nd gear 0 to 40mph, 3rd gear 40mph to 70+. You donot need anything better or bigger than this. NO CLUTCH as it isnt necessary. Batteries all fit in parcel shelf and in fron compartment. This car really gets a lot of attention on the road and in shows. If anyone needs any info on a VW conversion, I can help at [email protected]


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## corbin (Apr 6, 2010)

cruisin said:


> You guys are looking for numbers without any experience in reality. I have a 1970 beetle using a Impulse 9 motor, Kelly 800a controller and 117vdc 225ah 4866 Sanyo 18650 Li-ion cells, and use 2nd gear 0 to 40mph, 3rd gear 40mph to 70+. You donot need anything better or bigger than this. NO CLUTCH as it isnt necessary. Batteries all fit in parcel shelf and in fron compartment. This car really gets a lot of attention on the road and in shows. If anyone needs any info on a VW conversion, I can help at [email protected]


That's true! I have been in contact with Travis, who has a conversion similar to what I want to do.

How many watts/mile are you getting? 
Where did you get your cells from?

--corbin


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## Bowser330 (Jun 15, 2008)

cruisin said:


> You guys are looking for numbers without any experience in reality. I have a 1970 beetle using a Impulse 9 motor, Kelly 800a controller and 117vdc 225ah 4866 Sanyo 18650 Li-ion cells, and use 2nd gear 0 to 40mph, 3rd gear 40mph to 70+. You donot need anything better or bigger than this. NO CLUTCH as it isnt necessary. Batteries all fit in parcel shelf and in fron compartment. This car really gets a lot of attention on the road and in shows. If anyone needs any info on a VW conversion, I can help at [email protected]


great to hear from some real world experience...

What is your range like with the 26kwh pack? 100 miles to 100%DoD?
Where did you obtain your cells from?
Are u using a type of BMS?


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## cruisin (Jun 3, 2009)

I estimate the range to be 50-125 miles on a full charge depending on time of year, load, terrain, speed, etc. WH/mile are about 250 at 45mph in 3rd. Dont use 4th because that number will increase. Motor should be 3k-5k rpm for the best effecincy. Hills are no problem with a EV. power consumption is when on hills, cold weather, weight and speed. Cells are Sanyo Li-ion 18650 cells and yes I did all the wiring myself. My next project is a 912 and a Boxster which I have already started. I have added a couple of pictures for you to see. Suggestion, make sure you do a FULL restoration before the conversion, or else you will have many $$$ in a car nobody will want. Be prepared to do it right using only the off the shelf equipment available. I can give you a lot of help on the 12v side later when you are doing your conversion. YOU WANT EVERYBODY TO LOOK AT THE CAR AND SAY "CLEAN"


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## DavidDymaxion (Dec 1, 2008)

Your beetle is beautiful!

The 912 will make a great project, lots of room for batteries down low. I drove an electric beetle without a clutch, it shifted fine. My electric Porsche hates shifting without the clutch -- I'd urge keeping the clutch on a 911 / 912. Steve Clunn has converted a 911 or two and says the same thing about shifting.


cruisin said:


> I estimate the range to be 50-125 miles on a full charge depending on time of year, load, terrain, speed, etc. WH/mile are about 250 at 45mph in 3rd. Dont use 4th because that number will increase. Motor should be 3k-5k rpm for the best effecincy. Hills are no problem with a EV. power consumption is when on hills, cold weather, weight and speed. Cells are Sanyo Li-ion 18650 cells and yes I did all the wiring myself. My next project is a 912 and a Boxster which I have already started. I have added a couple of pictures for you to see. Suggestion, make sure you do a FULL restoration before the conversion, or else you will have many $$$ in a car nobody will want. Be prepared to do it right using only the off the shelf equipment available. I can give you a lot of help on the 12v side later when you are doing your conversion. YOU WANT EVERYBODY TO LOOK AT THE CAR AND SAY "CLEAN"


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## cruisin (Jun 3, 2009)

If you are having a problem upshifting on a EV Porsche, its because of a defective syncro which will hold true with any tranny. If you are having a problem downshifting on a good tranny with a good syncro, its because you dont know how to do it. It requires a technique comparable only to a EV. The VW and Porsche are designed very similar and shouldnt make any differance. My 6 speed BOXSTER EV shifts just like it did with a ICE, just cannot be in a hurry and NO speed shifting. For racing and other special needs, a clutch would be required.


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## DavidDymaxion (Dec 1, 2008)

Cruisin: Agreed lack of knowledge and worn synchros can make for hard shifts, even with the clutch! I would add a couple of things to your list: Synthetic transmission fluid can make some cars hard to shift -- it's too slippery for the synchros to work as designed in some cars. Also, some car makes are just hard to shift clutchless, good synchros or not.

I have driven a fair number of cars clutchless. Two Jeeps, an electric bug, and a 65 Mustang shifted easily without the clutch. Other cars were more difficult.

For example, my 4th gen Camaro will easily go into 1st gear at 30+ mph, I do that regularly in autocross. Obviously the synchros work great on this car. When the slave cylinder broke, it was very difficult to shift. You have to rev match near perfectly to get it to shift -- you definitely had to "know how to do it" to shift this car without a clutch!  This also shows you can have good synchros and still have a car that doesn't shift easily clutchless.

Regarding shifting my Electric 911: It's not a case of not knowing how to shift clutchless  . It seems to shift great with the clutch, except for going into 1st above about 20 mph with the motor at idle. It could be it has worn sychros, and it does have synthetic tranny fluid. It also, however, shifts great with the clutch and is very difficult to shift without.

A point in clutchless favor is that it reduces rotational inertia, which should help clutchless shifts. Even though I have a lightweight flywheel and a lightweight pressure plate, that's still ~10 more pounds of rotating weight clutchless wouldn't have.

As I want to race (and have steep hills to contend with), I'll take the lightning fast shifts with the clutch. I haven't heard of a clutchless 911/912's performance -- do you know of any?



cruisin said:


> If you are having a problem upshifting on a EV Porsche, its because of a defective syncro which will hold true with any tranny. If you are having a problem downshifting on a good tranny with a good syncro, its because you dont know how to do it. It requires a technique comparable only to a EV. The VW and Porsche are designed very similar and shouldnt make any differance. My 6 speed BOXSTER EV shifts just like it did with a ICE, just cannot be in a hurry and NO speed shifting. For racing and other special needs, a clutch would be required.


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## cruisin (Jun 3, 2009)

If you are going to use the car for compitition, you do need the clutch. In my EV cars I use 2nd from 0-40mph and 3rd from 40-65mph. Hardly never go any faster than that but it is capable. The only thing I dislike about the VW and Porsche tranny, is the noise level in 2nd and 3rd. I have dont as much as I could trying to cut down on the noise. By the way, when downshifting at 30mph as you do, you need to rev the motor watching your tachometer and you should have no problem.


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## DavidDymaxion (Dec 1, 2008)

Are you talking about your boxster or 912 with the gear noise? Just a data point, all the forward gears in my electric 911 sound similar. 

Yep, understood above revving to downshift, and I do that when I can. In autocross I can't change my pedals and remain in stock class, so the car isn't amenable to heel-and-toe, and there are time when I need to get into 1st while braking hard. That's definitely not a preferred way to shift, but fortunately the car gets only a few tens of shifts like that a year. The big point there was proving the synchros were good on the car, yet it was hard to shift clutchless compared to several other cars I have driven.


cruisin said:


> If you are going to use the car for competition, you do need the clutch. In my EV cars I use 2nd from 0-40mph and 3rd from 40-65mph. Hardly never go any faster than that but it is capable. The only thing I dislike about the VW and Porsche tranny, is the noise level in 2nd and 3rd. I have dont as much as I could trying to cut down on the noise. By the way, when downshifting at 30mph as you do, you need to rev the motor watching your tachometer and you should have no problem.


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