Gearing Up Motors

M

mham2k

New member
From everything I have read gearing up a motor isn't the best route to take because it lower electrical efficiency greatly and will cause lots of heat and ultimately kill my motors.

I need to get any combination of motors to 100000 rpm's on 12v.

My thoughts
- Buy one high rpm motor, there are some 10000kv drag racing motors. Not sure how long they last though, how much you have to cool them since they are probably built for a pass at a time. Which is why I am skeptical
- Gear up 2 or 3 RC motors to help with load while spinning one shaft. Obviously geared up.
- Use like 10 or 15 high KV drone motors to spin one shaft. (Nightmare to build). No hearing up by nightmare gearing and placement.
- Or I could get that high RPM 10000kv motor to spin me up to that speed then have the gear up motor(s) keep me there.


Any other thoughts?
 
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Do you want only 12v? Or you want to go higher? Going up in voltage will reduce the current for the ESC. It's possible to convert your 12v for your car to charge your higher voltage battery
 
i think you need to start at the beginning and work out the power required to achieve your goals

1)What engine size do you have..
2)What is readline rpm
3)What boost do you want to run at read line
4)What what run time are you looking for at max power... Realistic please ..

5) Are you trying to run this off the stock cars voltage (12-14.8v)

If you give us the information for these questions we can give you some solid estimations
 
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Ok my current setup on my 96 Eagle Talon TSI 4cylinder.

1.) Fully built motor ( I built it last year)
2.) HX35 turbo running 35psi of boost, puts me around 550 - 600hp. I get full boost at 4000 - 4500 RPM and ride it to 7500

This is a hobby for me and my car runs fine like it is so I will be happy to spend the time and learn what I need to before taking my car apart and putting an electric turbo on it.

1)What engine size do you have.. 4Cyl 2.0 L
2)What is readline rpm : 8500 but I only run to 7500
3)What boost do you want to run at read line, i currently run 35psi there and want to run the same
4)What what run time are you looking for at max power... Realistic please.
This is a fun street car, I want to be able to turn on full boost whenever the heck I want to without having to antilag and 2step or downshift to get back into boost. I want to be able to do a few pulls for 30 or 45 seconds then switch lanes ect, do another pull. Its a weekend warrior not a daily.

5) Are you trying to run this off the stock cars voltage (12-14.8v)
- I would love to I have no problem buying a 200 - 300 amp alternator to charge the battery. I found some powerful car audio batteries that will run 65ah a piece and I also found some nice LIPO car batteries that can do 100 - 300ah depending on the battery. Both are 12v systems.

My Logic (Could be way off, NEWB here)
Based on the compressor map of the test turbo I will be using (GT45). I need between 75000 - 85000 RPM's to get my to 35psi and the airflow that I want.

It seems that that RPM is at the peak of most of the electric motors on the market, I know from experience not to run anything at peak power for any period of time or things break.

This is where I get the 100k RPM, if I can come up with a system that can at peak give me 100k, I can run them between 65k and 85k on and off while having fun on the street no problem.

Things that make no sense to me right now, wrapping my head around them
1.) The blower
I read the forums that the guys made 5psi ish from the blower thing, the spec on the website says it has a max spin of 52000 rpm, do 22psi, . In one video the guy was spinning it at 65000 rpm and not getting anything airflow close to something that would give 80 lb/min (800hp). It seems that the blower company is false advertising and the guys that are spinning them can get much better airflow, at the same rpm from a higher quality blower/turbo, many turbo's spin at 65000 rpm and give you 15 - 30psi and 50 - 70 lbs/min of air no problem.

OR I am missing something about the RPM.

2.) The batteries
I don't understand this just yet, trying to get my mind around the math.
I get that more volts means you use less amps, and I can step up my car voltage to charge a higher volt system no problem
I can install at 200 or 300amp alternator no problem
I get the higher KV more rpm but less torque, and vice versa
More Amps More Heat? More Volts less heat, smaller wires?
Trying to understand the right balance of volts vs amps, and how much a motor can handle.

My back of the envelope math based on another guys post tells me at 48v i need about 100ma to spin my turbo where i want it. Can i just divide this down to 12 volts and say at 12v i need 400ma or is there some formula?

3.) The motors
There are so many options and pairings that its hard to know what to choose. Seems that most on this forum resort to using one motor. I'm sure there is a good reason i just don't get it yet, i probably will soon.

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Updated Thought Process
I just took a look through https://theecharger.com/, learned a lot and now have another idea.

Now if i take a step back and look at the problem I'm trying to solve, I want to solve my lag problem at low boost. Instead of making the entire car run from an electric turbo i should be able to compound it. I could work with a 20000 - 50000 rpm motor to give me boost from 1000 - 5000 while my main turbo spools up and then trail off the electric or slow it down for a little extra power when i want it...

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I think this is probably the best option here, what do you think? I can do this on a 12v system with a 3000 - 5000kv motor. Thoughts?

Thanks for all of the help, just dumping my entire brain out right now. Want to understand this stuff and really build something cool.
 
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Well 2L @ 7500 @ 35psi requires some 105hp (78kw) into the turbo shaft..
While possible this seems rather un realistic..

At 12v that is some 6500 amps, which is also "rather un realistic"

I believe the the e-turbo setups designed to lessen turbo lag are obviously less powerful and then by passed at higher rpm when the turbo takes over. We did this back in the day with twin charged cars roots SC and turbo on the same car.

Any chance you could post some dyno's ideally with boost along the bottom.
 
As for batteries if they are 65ah you'd need 100 for and hour, 50 for 30 min 25 15min 12.5 for 7.5min... I imagine that would take up alot of space and weigh alot to say the least.

Updated got the math wrong lol
 
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For the rpm you can use a 10:1 gearbox so for 60,000rpm you only need a motor running at 6000rpm but you will also need a lot more torque
 
MkngStffAwesome said:
As for batteries if they are 65ah you'd need 1000 for and hour, 500 for 30 min 250 15min 125 for 7.5min... I imagine that would take up alot of space and weigh alot to say the least.
Click to expand...

Ok wow, that's the info I was trying to figure out.

I have never been to a Dyno, I measure hp roughly by using lb/min and street tune my car.

So what would you say I needed to get 20psi at 3500rpm? That would be sufficient*
That's about a 40k spin on the turbo

The larger the turbo the less RPM it takes to make boost and good lb/min but obviously the more torque it takes to spin the shaft. GT45 is pretty big, no problem going larger if needed.
 
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I personnaly use a TP 4070-CM for my GT35. Rated at 9000w at 75k rpm. I've been able to get arround 40k-50k RPM. I will probably get et nice 50k RPM with my new battery. BUT there's some motor even more powerfull like the LMT 30100 with the crazy 40'000w. Motor is about all the same when we talk about torquy motor they all arround 50k RPM. So they are some motor capable of enough torque to get clost enough ton 50k RPM. I think its a waste of time searching for motor up to 100k RPM
 
mham2k said:
Ok wow, that's the info I was trying to figure out.

I have never been to a Dyno, I measure hp roughly by using lb/min and street tune my car.

So what would you say I needed to get 20psi at 3500rpm? That would be sufficient*
That's about a 40k spin on the turbo

The larger the turbo the less RPM it takes to make boost and good lb/min but obviously the more torque it takes to spin the shaft. GT45 is pretty big, no problem going larger if needed.
Click to expand...
sorry i had the battery math wrong

20psi at 3500 rpm is about 26hp.. or 19kw... this is some thing similar to alexis first build.. 60v * 300amp = 18kw.
At 19kw at 12v is 1583amps. This current is unrealistic for one ESC and motor BUT @ 60v which drops the current to 300amps that is achievable.
 
WB projects said:
I personnaly use a TP 4070-CM for my GT35. Rated at 9000w at 75k rpm. I've been able to get arround 40k-50k RPM. I will probably get et nice 50k RPM with my new battery. BUT there's some motor even more powerfull like the LMT 30100 with the crazy 40'000w. Motor is about all the same when we talk about torquy motor they all arround 50k RPM. So they are some motor capable of enough torque to get clost enough ton 50k RPM. I think its a waste of time searching for motor up to 100k RPM
Click to expand...

Your running 48v 20 ah correct? What are you moving to?

Based on Awesome's calcs that would be way underpowered, does your electric motor spool up quick or slow attached to the turbo?

Can you show your me your setup? How did you connect the motor to the back of the compressor wheel? I have some ideas but none are great.
 
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MkngStffAwesome said:
sorry i had the battery math wrong

20psi at 3500 rpm is about 26hp.. or 19kw... this is some thing similar to alexis first build.. 60v * 300amp = 18kw.
At 19kw at 12v is 1583amps. This current is unrealistic for one ESC and motor BUT @ 60v which drops the current to 300amps that is achievable.
Click to expand...

Is this best to build a battery that can handle that, it looks like they are a few thousand dollars to buy.

Thats 60v 300ah correct?

Some of these battery claim high amperage but low ah, i assume the high amperage is for burst not long term use. Like cranking amps on a car battery.

So if this is true, I should be able to use it like nitrous. Supply high amperage for a small period of time, maybe the 5-10 second need to allow my main turbo to take over then cut it off. This means I can use a battery with high cranking amps but a lower ah.

Cranking Amps: is defined as a measurement of the number of amps a 12 Volt battery can deliver for 30 seconds at 32°F and not drop below 7.2 volt.

These car audio battery can deliver 1100 cranking amps for 30 seconds or 5 - 10 second bursts of 3000 amps.
I could also add a capacitor to the system as well if needed

18kv at 12v = 1500 amps needed in burst.

I can hook it up to a button on my wheel and press it when I want the power.

Thoughts on that idea? Esc problem still I assume?
 
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mham2k said:
Your running 48v 20 ah correct? What are you moving to?

Based on Awesome's calcs that would be way underpowered, does your electric motor spool up quick or slow attached to the turbo?

Can you show your me your setup? How did you connect the motor to the back of the compressor wheel? I have some ideas but none are great.
Click to expand...
At the time, I was using small LTO battery of 33v (with the voltage drop I was at 24v if I remember due to a lot of factor) 5.9Ah. now im moving the to pouch battery and hopfully having a big improvement.

I programmed my ESC to spool in less then 2 sec I think

Go check my YT channel I have all on it
 
WB projects said:
At the time, I was using small LTO battery of 33v (with the voltage drop I was at 24v if I remember due to a lot of factor) 5.9Ah. now im moving the to pouch battery and hopfully having a big improvement.

I programmed my ESC to spool in less then 2 sec I think

Go check my YT channel I have all on it
Click to expand...

This is great, i'm gonna go watch all of your videos.
 
mham2k said:
Is this best to build a battery that can handle that, it looks like they are a few thousand dollars to buy.

Thats 60v 300ah correct?

Some of these battery claim high amperage but low ah, i assume the high amperage is for burst not long term use. Like cranking amps on a car battery.

So if this is true, I should be able to use it like nitrous. Supply high amperage for a small period of time, maybe the 5-10 second need to allow my main turbo to take over then cut it off. This means I can use a battery with high cranking amps but a lower ah.

Cranking Amps: is defined as a measurement of the number of amps a 12 Volt battery can deliver for 30 seconds at 32°F and not drop below 7.2 volt.

These car audio battery can deliver 1100 cranking amps for 30 seconds or 5 - 10 second bursts of 3000 amps.
I could also add a capacitor to the system as well if needed

18kv at 12v = 1500 amps needed in burst.

I can hook it up to a button on my wheel and press it when I want the power.

Thoughts on that idea? Esc problem still I assume?
Click to expand...
Something like that.. If your going to stay with 12v then you'd probably need an array of ESC's and motors. so it's much cheaper and smaller to just up the voltage and use one esc and one motor
 
MkngStffAwesome said:
Something like that.. If your going to stay with 12v then you'd probably need an array of ESC's and motors. so it's much cheaper and smaller to just up the voltage and use one esc and one motor
Click to expand...

Is it ok to step up the 12v system to 48 or 60 or do i need to start with the higher voltage battery then step up after the alternator to charge it.

I'm thinking something like this could be a good start.
 
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Dont try to step up your voltage to spin your turbo.. start with bigger voltage battery. Then use your step up to charge the battery. Dont need bigger alternator
 
WB projects said:
Dont try to step up your voltage to spin your turbo.. start with bigger voltage battery. Then use your step up to charge the battery. Dont need bigger alternator
Click to expand...
Ok thanks. I'm gonna start at 60v and 20 to 50ah and build a system around that.

When it comes to motors and esc anything specific I should look for? Maybe a 2500 or 3000kv motor with a good brand name that can handle 100 amps and 60v.
 
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