# How to define the best motor/ gear box



## OliverH (May 27, 2018)

I'm new to conversions and try to prevent typical mistakes. Currently I try to get a feeling based on theoretical comparisons to find the best combo.
The chart represent a VW T2b with CP gearbox, Curtis AC50 (96V). This combo is possibel - not the best.
Note: Peak power, based on converted torque values of HPEVS diagrams, which are not consistent. Rated power is much lower.




Explanation:


blue curve is the drive resistance (wind drag, loss of gear box, wheel resistance, load of the vehicle, incline/ slope (0%)).
The other colors are the max power in the gears over speed.
If the gear curve cross the blue line it defines the max. speed in this gear.
How did you figure out your matching setup?


----------



## brian_ (Feb 7, 2017)

I believe that you are already well above the level of sophistication of typical DIY project (electric or gasoline) in this analysis. Looks good to me.

I would add that in addition to illustrating the top speed, the available power in excess of the power required to overcome the calculated resistance is the power available to accelerate.


----------



## Duncan (Dec 8, 2008)

Hi
Re-do your graph

You want to have torque and not power on the axis 

Then you will be able to instantly see the amount of "extra" torque above the "steady state" torque that you will have available with each gear


----------



## brian_ (Feb 7, 2017)

Duncan said:


> You want to have torque and not power on the axis
> 
> Then you will be able to instantly see the amount of "extra" torque above the "steady state" torque that you will have available with each gear


Sure, that would be proportional to acceleration, rather than rate of kinetic energy gain... as long as you are doing torque at the wheels (or at least at the final drive input), not at the motor. And you really want it to be drive force (not torque), corresponding to what has already been calculated for "resistance". 

It's the same information, just differently presented... but fortunately, it's an easy transformation.


----------



## aquabiologist (Sep 8, 2017)

Nice!

Finally, I can put my own spreadsheet from hell put to use.

The following shows:

Torque at the Motor for a vw t2ab with original gear ratio for the Hpevs 50, the netgain hyper 9, plus the original 1600cc ice. 

The ‚drag torque‘ is based on car weight, coefficient of drag, stock tires, road friction plus some guesstimate losses for the gears.
















With these numbers: the hpevs ac 50 seems a bit underpowered for a vw t2 if you want to be able to run on highways for longer trips.
The hyper 9 seems a nice replacement for the 1600cc engine.




Gesendet von iPhone mit Tapatalk


----------



## OliverH (May 27, 2018)

The 1600 (AS?) is the 50 HP engine? I had such a T2b many decades ago. This one was totally underpowered. I like to replace a Type 4 2.0 as a california edition (fuel injection, TSZ-H ignition, catalyst with lambda sensor). As we made a year ago the EV step with the family car the T2 should follow now. 
The diagram below is the minimum witch is possible. It’s just for orientation and not the preferred path. I’ll post the same diagram with a 5% slope to show the “problem”:
The 4th gear is not usable. 3rd gear is limited at close to 80 km/h with not much power buffer.


----------



## OliverH (May 27, 2018)

Netgain HyPer 9 (peak performance) flat road..


----------



## OliverH (May 27, 2018)

Netgain HyPer 9 (peak performance) 5% slope.. 

It outperforms the Curtis AC50 with no doubt. But the torque could be to much for the 091 CP gear box. Rumors say it withstand round about 200 Nm and the HyPer 9 could distribute 235 Nm. Weddle gears could solve the problem.
The main question is to go with the original/ modified gearbox or a drive train with reduction gear box (Tesla, GKN, Getrag,..). That's the reason for this thread.


----------



## Boxster-warp (Jun 22, 2014)

Hallo Oliver
Heiko fleck sell now the scottdrive controller with an watercoled Motor.
600 ampere and 350v.
Nice combi.
Greeitings boxster-warp


----------



## OliverH (May 27, 2018)

Boxster-warp said:


> Hallo Oliver
> Heiko fleck sell now the scottdrive controller with an watercoled Motor.
> 600 ampere and 350v.
> Nice combi.
> Greeitings boxster-warp



The question is to find an e-engine which fits to the original gear box or use a drive unit. Our beloved historical cars are worth to spend some more money with the right solution. But interesting to see his 210 KW (a gear box cruncher) engine which is not listed on his shop. That's a reason to talk with Heiko Fleck and Kreisel 1to1 in summer.


----------



## brian_ (Feb 7, 2017)

aquabiologist said:


> The following shows:
> 
> Torque at the Motor for a vw t2ab with original gear ratio for the Hpevs 50, the netgain hyper 9, plus the original 1600cc ice.
> 
> The ‚drag torque‘ is based on car weight, coefficient of drag, stock tires, road friction plus some guesstimate losses for the gears....


Expressing this all as torque at the motor/engine output is a little strange, because

it makes it look like drag takes steps at the points where you have chosen gear shifts (25, 50, and 80 km/h)
it forces all power sources (engine, both motors) to follow the same shift points, whether they are appropriate or not.

It would make more sense to me to do force at the tires, torque at the axles, or torque at the transmission output (they would all work similarly), so the drag would be the continuous curve that Oliver shows, and each power source (engine and both motors) can step through the gears at the points suitable for the specific source.

If your spreadsheet is in some commonly consumable source form (Excel file, Google Sheet, etc) and you are willing to share it, I might try the alternate presentation.


----------



## aquabiologist (Sep 8, 2017)

brian_ said:


> Expressing this all as torque at the motor/engine output is a little strange, because
> 
> it makes it look like drag takes steps at the points where you have chosen gear shifts (25, 50, and 80 km/h)
> it forces all power sources (engine, both motors) to follow the same shift points, whether they are appropriate or not.
> ...




It does look odd and is for my gearing, but torque at wheel would not compare to motor specifications. So thats why. 

Thanks for your offer to do the other graphs. Did i mention its a spreadsheet from hell? I seriously need to clean it up first  


Gesendet von iPhone mit Tapatalk


----------



## aquabiologist (Sep 8, 2017)

OliverH said:


> Netgain HyPer 9 5% slope..
> 
> It outperforms the Curtis AC50 with no doubt. But the torque could be to much for the 081 CP gear box. Rumors say it withstand round about 200 Nm and the HyPer 9 could distribute 235 Nm. Weddle gears could solve the problem.
> The main question is to go with the original/ modified gearbox or a drive train with reduction gear box (Tesla, GKN, Getrag,..). That's the reason for this thread.




I always assumed that you could set max. torque in the controller software?


Gesendet von iPhone mit Tapatalk


----------



## OliverH (May 27, 2018)

aquabiologist said:


> Nice!
> 
> Finally, I can put my own spreadsheet from hell put to use.
> 
> ...



Why do you've steps in the drive resistance curve? The ideal curve should be smooth. My curve is also only a calculation and reality could vary (different resistance at different speeds of the gearbox, bearings axle shaft, bearings on the wheel hubs) but this should be a small different


----------



## aquabiologist (Sep 8, 2017)

OliverH said:


> Why do you've steps in the drive resistance curve? The ideal curve should be smooth. My curve is also only a calculation and reality could vary (different resistance at different speeds of the gearbox, bearings axle shaft, bearings on the wheel hubs) but this should be a small different





As i shift, rpm drops, the minimum torque at the motor to overcome ‚drag’ must increase. Power output would be a smooth curve. 

This way I can limit my motor torque, so it won‘t kill my gearbox. And estimate the performance of my setup. At least thats what i think i am doing.


Gesendet von iPhone mit Tapatalk


----------



## brian_ (Feb 7, 2017)

aquabiologist said:


> It does look odd and is for my gearing, but torque at wheel would not compare to motor specifications. So thats why.


Engine or motor, both can be compared at the same point in the drivetrain. You multiply the engine or motor torque by the transmission ratio (for transmission output) and by final drive drive ratio (for axle torque) and divide by tire radius (for driving force) in either case.



aquabiologist said:


> Thanks for your offer to do the other graphs. Did i mention its a spreadsheet from hell? I seriously need to clean it up first



Well, I'm still willing to at least have a look!
Don't clean it up just for me.


----------



## brian_ (Feb 7, 2017)

OliverH said:


> Why do you've steps in the drive resistance curve? The ideal curve should be smooth.


The curve of torque at the wheel or at the transmission output is a smooth function of speed... but this graph shows torque at the motor/engine output or transmission input, so it is the torque at the transmission output (smooth like yours) divided by the gear ratio being used at that road speed.


----------



## brian_ (Feb 7, 2017)

aquabiologist said:


> I always assumed that you could set max. torque in the controller software?


By limiting current, yes. That's what I was thinking, too.


----------



## brian_ (Feb 7, 2017)

aquabiologist said:


> As i shift, rpm drops, the minimum torque at the motor to overcome ‚drag’ must increase. Power output would be a smooth curve.
> 
> This way I can limit my motor torque, so it won‘t kill my gearbox.
> ...
> At least thats what i think i am doing.


On the other hand, transmissions are normally rated by torque input (rather than output), so for any given required power output, you can go easier on the transmission by using higher motor speed and lower transmission input torque, which means staying in a lower gear, within the maximum rated input speed of the transmission and the efficient speed range of the motor.


----------



## aquabiologist (Sep 8, 2017)

brian_ said:


> Engine or motor, both can be compared at the same point in the drivetrain. You multiply the engine or motor torque by the transmission ratio (for transmission output) and by final drive drive ratio (for axle torque) and divide by tire radius (for driving force) in either case.
> 
> 
> 
> ...




Ok, but you have been warned 

First: I am a biologist so go easy on me with all the technicalities. Its aimed at predicting my conversion and i believe its as close as i can get. Tested it against commercial EVs and its good enough for me.

Btw: works only with excel

Here is my spreadsheet from hell for EV calculations

https://docs.google.com/file/d/1Zjl...Nftddp/edit?usp=docslist_api&filetype=msexcel




Gesendet von iPhone mit Tapatalk


----------



## brian_ (Feb 7, 2017)

aquabiologist said:


> ... Btw: works only with excel
> 
> Here is my spreadsheet from hell for EV calculations
> 
> https://docs.google.com/file/d/1Zjl...Nftddp/edit?usp=docslist_api&filetype=msexcel


The first good news is that the XSLX file does open in Google's Chrome extension for Office documents. 

More good news: I tried saving it as a Google Sheet, and it was apparently successful.

While I haven't seen anything I can't work with yet, I have only started looking...


----------



## OliverH (May 27, 2018)

A couple of gearbox and motor simulations later I found two options worth to follow on:


Original Gear box and Brusa 6.17.12/ DCM524 (reduced peak perf) or the Netgain HyPer9 (reduced peak perf)
Brusa 6.17.12/ DCM 534 and a BMW i8 2 speed gearbox (if matching)
Limiting the peak performance in combination with the VW gear box is based of torque limitations. 



We've some limitations from regulations:


The car must be able to start at a 15% incline from stand still
The rated motor performance is used/ peak performance could be higher for a short time
in the age of our T2 a power step of additional 20 HP is allowed without modifications (max 90 hp)/ an approval for 119 hp is available from a parts dealer in switzerland
So in the end the motor dictates the electronic parts: 96V or 400V


----------



## OliverH (May 27, 2018)

Looks like Brusa doesn''t sell anymore to endusers.
So the options are HPEVS (AC50/ AC51) and Netgain HyPer9.


----------



## EVSpitfire (Feb 28, 2014)

You can purchase Bursa from these guys

http://www.metricmind.com/products-services/


----------



## OliverH (May 27, 2018)

EVSpitfire said:


> You can purchase Bursa from these guys
> 
> http://www.metricmind.com/products-services/



This company is in America and I'm in Switzerland 200 km far away from Brusa. Brusa was my favour. Maybe I need to go to the company in Austria (190 km) building the motors for Brusa. I'm passing this town in July on my holiday trip.


Currently following the Netgain Hyper9 (Aircooled only) path (35 KW rated?!) and two other manufacturer in Europe 



Schwarz (http://www.schwarz-elektromotoren.d...ktrofahrzeuge/elektromotoren-fuer-elektroauto)
Hofer Powertrain (https://hofer-powertrain.eu/en/system/electric-drive-unit/) - no products, only prototyping/ consulting and development for automotive companies.
And last but not least I need to talk to Heiko Fleck if he has something which is not listed on his page. There mas mentioned an water cooled motor.
Buying from an European manufacturer has may be less problems in case of a failure (parts/ warranty, time for shipping).


Choosing the motor and the voltage gives me the sope of all other components. Worst case would be choosing a motor good on paper which sucks in the car as I operate the motor out of the rated area. If I look on the netgain Hyper9: Is the 35 KW rated power true? Than I can't go 100 km/h on trips as my driving resistance is higher. Driving long slopes in Germany on the Autobahn/ highway could be an adventure/ nightmare. I don't like to spend money to waste it and rebuilt/ redesign the concept from ground up again.


----------



## OliverH (May 27, 2018)

Was last week at Heiko Fleck with my wife and we talked about the project, the requirements and we found a solution after talking about charging (CCS) speed and we defined a complete 300-400 V system (because of CCS, to get high charging power)
44 KW motor, made in Germany with CE
Adapter plate with original clutch/ flywheel
Scott Drive MCU with CE
Tesla batteries with OS BMS modules for Tesla batteries
Vacuum pump kit (Hella)
A charging kit with CCS, available somewhere next year

Just sitting on a doc to write down the specs to enter discussion with approval agency. Try to get a meeting in the next weeks.


----------



## Boxster-warp (Jun 22, 2014)

Hello
Cool, i Must Visite Heiko in the Future too.
Since 2 years where Talking per Smartphone.

The scottdrive ist my Favorit too.
Greetings Boxster-warp

Edit but 200-250v Are enough for me.
Ccs ist new Info, cool.
Chademo is my Favorit, 200v is enough.

The 44kw Motor is watercooled?


----------

