[Bowser330]

Long time member here, I remember back when Mate Rimac was just one of us and not an EV Supercar CEO.

I always have and still want to work on a DIY EV project but was taken by the performance and value of the model 3 performance, so i bought one.

However I would like to get this community's opinions, advice and guidance on increasing the performance of the P3D.

I had a few ideas and once you deem me crazy I would be interested to hear new ideas from you all.

(1) install an independently powered and controlled 3rd motor (Tesla model s front motor) on to a 5th wheel that would make contact to the road under/within the rear trunk.

(2) install an independently powered and controlled 3rd motor (Tesla model s front motor) to the rear of the model 3 and connect the inner cv axles of the oem rear motor and 3rd motor with a belt or chain, on both sides of course, to couple the oem rear motor and 3rd motor together.

(3) install hub motors at the output of the tesla oem motor gearbox and get custom shorter cv shafts made.

I do realize that all the options represent a lot of work and would require material amounts of customization, i guess i am wondering if they are even possible from an engineering and reliability perspective.

Is there another more obvious option I am missing?

Advice?

 

[Duncan]

Long time member here, I remember back when Mate Rimac was just one of us and not an EV Supercar CEO.

I always have and still want to work on a DIY EV project but was taken by the performance and value of the model 3 performance, so i bought one.

However I would like to get this community's opinions, advice and guidance on increasing the performance of the P3D.

I had a few ideas and once you deem me crazy I would be interested to hear new ideas from you all.

(1) install an independently powered and controlled 3rd motor (Tesla model s front motor) on to a 5th wheel that would make contact to the road under/within the rear trunk.

(2) install an independently powered and controlled 3rd motor (Tesla model s front motor) to the rear of the model 3 and connect the inner cv axles of the oem rear motor and 3rd motor with a belt or chain, on both sides of course, to couple the oem rear motor and 3rd motor together.

(3) install hub motors at the output of the tesla oem motor gearbox and get custom shorter cv shafts made.

I do realize that all the options represent a lot of work and would require material amounts of customization, i guess i am wondering if they are even possible from an engineering and reliability perspective.

Is there another more obvious option I am missing?

Advice?

Those options would ALL result in REDUCED performance
The main limiting factor is the ability of the tyre/road interface to transmit power to the ground and those options all make that WORSE

I would suggest instead
(1) Reduce weight - there is a lot of luxury in a model 3 - all of which can go
(2) Improve suspension/brakes
(3) This is the expensive one - you need to "hack" the software and increase the power
The Tesla is operating on a compromise because it expects 200,000 miles with no failures
If you are willing to accept a greater chance of failure (which is what "tuning is all about" THEN you should be able to stretch the power a good bit

 

[Bowser330]

Those options would ALL result in REDUCED performance
The main limiting factor is the ability of the tyre/road interface to transmit power to the ground and those options all make that WORSE

I would suggest instead
(1) Reduce weight - there is a lot of luxury in a model 3 - all of which can go
(2) Improve suspension/brakes
(3) This is the expensive one - you need to "hack" the software and increase the power
The Tesla is operating on a compromise because it expects 200,000 miles with no failures
If you are willing to accept a greater chance of failure (which is what "tuning is all about" THEN you should be able to stretch the power a good bit

Thank you for the response!

Please help me understand.

i dont quite understand why an additional motor providing an additional lets just say 100hp of assistance makes the performance worse?

I was under the assumption that power at the wheels was additive if we had more power and more wheels its additive. Is the 100hp 5th wheel not powerful enough so it becomes a drag/load for the other 4 wheels to carry?

if so what if it had 200hp then it would have more power than any one wheel of the OEM tesla? if it had 250hp it would have just as much as the entire axle of the tesla, how could that make performance worse to add 250hp?

You are absolutely correct about lightening the car and upgrading the suspension, both things in the works.

the hacking the SW part is something that hasn't been figured out yet so that's really a non-starter as there is no current way to do it. There isn't even a way to hack the later year model s's. all the model s motors and independent controllers you see on the market are from the older firmware that was cracked (from what i heard).

 

[Duncan]

Power at the wheels is additive - however your extra wheel will need to push against the ground if it is to transfer any power to the tarmac
And that load will come OFF the load the road wheels are carrying - which means that they will not be able to put as much power to the road

So you will add power from your extra wheel and LOSE power from the main wheels

 

[ishiwgao]

my thoughts on what you are suggesting

(1) install an independently powered and controlled 3rd motor (Tesla model s front motor) on to a 5th wheel that would make contact to the road under/within the rear trunk.

The basics on why this is not a good idea was already covered by Duncan. I would add that the addition of the complexity of introducing the wheel and mechanisms to hold it makes this idea not very good for your purpose of increasing performance

(2) install an independently powered and controlled 3rd motor (Tesla model s front motor) to the rear of the model 3 and connect the inner cv axles of the oem rear motor and 3rd motor with a belt or chain, on both sides of course, to couple the oem rear motor and 3rd motor together.

This may help improve performance in theory. However, you need to watch out for a few things:
1) load capability of the differential. Can it handle the torque/power from 2 motors?
2) traction capability of the tyres. Can it handle the torque from 2 motors, or will it just start spinning from the additional torque. (at higher speeds I guess it may be better, but from standstill this issue will be there)
3) is the belt connecting both motors able to withstand the torque of the motor and not just snap?

(3) install hub motors at the output of the tesla oem motor gearbox and get custom shorter cv shafts made.

Among your 3 ideas, my opinion is this might be the best one (least amount of work required with decent performance gain, but slightly complex on the electrical side due to different voltage of the model 3 motor and hub motor). Still agree with Duncan that other options like lightweight-ing the car is better.

This concept is similar to what Koenigsegg is doing with the Regera/Gemera rear drivetrain. however for you, instead of using an ICE engine, you're using the Model 3's motor.

This is slightly more expensive on the motor side, because hub motors are fairly expensive for the power they provide. a cheap one used on bicycles will only give you single digit kW. you can go a bit higher to get those used on scooters/bikes, but the size (thickness) gets bigger and may affect the car's handling performance with the shorter CV axles.

The money-no-issue option is to use the same pancake motors as Koenigsegg (Yasa, or other brands) which are super thin and provide lots of power (>200kW each).

 

[Duncan]

Hub motors will almost certainly result in LESS power delivered to the tarmac

You may have more power but the additional unsprung weight will ruin the performance of your suspension and as a result you will end up delivering LESS power

Remember that a performance model Tesla is already delivering MORE power to the tarmac than was thought to be possible just ten years ago

 

[brian_]

It seems to me that all of these ideas are far too complex to make any sense. Just hack the controller for more performance at the expense of lower efficiency and reliability. When the car dies as a result, throw it out and get another one, for less expense than tacking on additional motors and gearboxes.

Hub motors will almost certainly result in LESS power delivered to the tarmac

You may have more power but the additional unsprung weight will ruin the performance of your suspension and as a result you will end up delivering LESS power

Although they were referred to as "hub motors", the state plan was to place them at the drive unit outputs, which would be inboard. If inboard, they would not increase unsprung mass and thus not cause the consequent problems.

 

[remy_martian]

When you say "performance", I'm going to guess you mean acceleration. Next question is which kind?

0-60mph) 100kmh)?

1/4 mile?

Top speed?

The second easiest way to get 0-60 is by changing the ratios in the gearbox in trade for top speed. The first was already mentioned by others...hack the drive electronics. Damien McGuire is on the verge of having cracked driving the M3 motor. The brutal punishment way is to shoehorn a large drive unit, or adapt the LDU motor to the M3 gearbox....prob easier than dual motor on one axle (DOT term, not half shaft count). Bigger motors front and back, then hack them.

There are many other ways, but you don't state your background/resources. Reading a forum for a couple of decades is a start, but skills & knowledge are two very separate things. Sounds like you have bags of money to pay for an ego stroking.

Maybe you should do a motorcycle if you really want your eyeballs rattling around in the back of your skull?

 

[Bowser330]

Thank you for guidance and advice. The altering of the gear ratio is a good one, would be very interesting to see how quick 0-60 a model 3 could be and still be used normally/daily. didn’t stillen do that to the model s?

I’m a biomedical engineer but have been interested in cars and electric cars for sometime. I have limited hands on skills I will admit and would of-course collaborate with those with experience once an idea was determined to have any real merit. I wasn’t aware the hacking of the model 3 inverter was that far along, thank you.

I listed options because I wanted to get a conversion going on what the real options are, what the experts on this forum, way smarter than me, think. My options were foolish I admit, third motor?! super complicated, it would cost to prototype and then there is the advice of it actually robbing power? But I had to ask to learn it was a bad idea. Difficult to find reading material about this online. It’s either here or another engineering forum.

Also, I don’t have bags of money and any ego to stroke, however there are those out there that do that might want to fund a project in this space.

 

[Duncan]

Re altering the gear ratio

It may not help you!
Once you have enough torque to spin the wheels then more is not useful

I'm pretty sure that a Model 3 performance already has enough torque to spin the wheels and that it uses its software to control that torque

Sticky "race" tyres will give more performance improvement than that