Open Source Electric Supercharger

[KroozX]

I've already built pretty the same setup. The result was pretty interesting:

[ame]https://www.youtube.com/watch?v=f9w4qTTLKVo[/ame]

[Matt@Cosworth]

the figures are a little difficult to read off the meter and gauge
what does this setup reach / achieve in terms of pressure and mass airflow?

[KroozX]

It makes about 0,5 Bar at 120-130kg/hr airflow. The most interesting thing is that the power used for this is only about 3-3,5KW. I'm pretty sure this compression wheel is not the most efficient one, so prboably there is a way to improve the setup even further.

[churchx]

I wonder which type of chargers may fit better to pair with electric motors, centrifugal or positive displacement ones ..

Thinking that there might be more gains with centrifugal, as electric, non mechanically linked to engine, may have less problems spinning fast at low engine rpms, and i guess having turbine might simplify not designing in bypass for when ESC is not on, or there might be some pros to positive displacement one + ESC too?

[al3k]

Originally Posted by KroozX

I've already built pretty the same setup. The result was pretty interesting:

Can you share how you mounted the compressor wheel to the motor and how you mounted the motor to compressor housing, sealing methods?

Which motor (kv) and voltage to motor did you test in video?

[KroozX]

The motor is tp4070cm 2200kv, powered from 12S LiPo with custom developed motor controller. I turned the wheel on the lathe to the shaft diameter and fixed it with a screw. No extra sealing except of the turbo housing ones, which is already there.

[al3k]

Originally Posted by KroozX

The motor is tp4070cm 2200kv, powered from 12S LiPo with custom developed motor controller. I turned the wheel on the lathe to the shaft diameter and fixed it with a screw. No extra sealing except of the turbo housing ones, which is already there.

nice! you should turn on sound in your video, I couldnt hear it spool.

"It makes about 0,5 Bar at 120-130kg/hr airflow."
Are you sure you are measuring this the correct way? 120-130kg/hr doesnt make sense if you maxet out your motor or did you mean 120-130g/s?

[Matt@Cosworth]

Originally Posted by churchx

I wonder which type of chargers may fit better to pair with electric motors, centrifugal or positive displacement ones ..

Thinking that there might be more gains with centrifugal, as electric, non mechanically linked to engine, may have less problems spinning fast at low engine rpms, and i guess having turbine might simplify not designing in bypass for when ESC is not on, or there might be some pros to positive displacement one + ESC too?

a PD blower will take a lot more shaft power to turn I'm afraid
centrifugal are the only viable option at the motor power levels we're talking about

[KroozX]

Originally Posted by al3k

nice! you should turn on sound in your video, I couldnt hear it spool.

Sorry for no sound, there was something wrong with my camera. I definitely should make the one with the sound.

Originally Posted by al3k

"It makes about 0,5 Bar at 120-130kg/hr airflow."
Are you sure you are measuring this the correct way? 120-130kg/hr doesnt make sense if you maxet out your motor or did you mean 120-130g/s?

According to the datasheet of the used MAF sensor, it gives 2,8V output voltage on about 120-130kg/hr airflow. The gas flow calculator says it corresponds to ~100m3/hr or ~1500-1600 l/min. If I'm correct it also corresponds to about 1500rpm of 2,0 liter engine.
It probably could look like the pipes are simply opened, but it's not the case. I made a kind of throttle valve in the middle section of the piping:

[Matt@Cosworth]

Something I meant to ask when I 1st saw your video was why aren't you measuring the air flow on the compressor intake?

as presumably your dummy manifold has a restrictor of some sort in it ( you mention a throttle above) so it can generate some boost

but if you're measuring downstream of that restrictor then there will be pumping losses so you are being a bit unfair to it I feel

also looking at your MAF datasheet 2.8V = about 180kg/hr so 50 g/sec if its a Pierberg unit or 70 Kg/ hr if its a Bosch unit?

[KroozX]

Originally Posted by Matt@Cosworth

Something I meant to ask when I 1st saw your video was why aren't you measuring the air flow on the compressor intake?

No, I'm measuring on the output of the compressor, after "manifold" and throttle

Originally Posted by Matt@Cosworth

looking at your MAF datasheet 2.8V = about 180kg/hr so 50 g/sec if its a Pierberg unit or 70 Kg/ hr if its a Bosch unit?

It's a Bosch sensor. I made a screenshot from the video (in attached fotos), it shows about 2,94V top flow. Looking more precisely to the diagramm from datasheet (attached foto) there is about 110-115kg/hr airflow. Which is a bit less, than I assumed before, thanks for the correction. So such airflow is at approx 1400rpm of the 2,0L engine.


Anyway I was really surprised achieving even this result after looking the videos of other ESCs.

Originally Posted by Matt@Cosworth

but if you're measuring downstream of that restrictor then there will be pumping losses so you are being a bit unfair to it I feel

Which pumping losses do you actually mean? I also thought about moving the MAF sensor to the intake of the ESC, but not really sure if it could be any better.

[al3k]

Would be interesting to see if putting the maf to the inlet changes the results.
Did you measure the inducer and exducer of the compressor wheel? This is a T04E right?

[KroozX]

The compressor wheel is 48/75mm. There is also a pretty big gap between wheel and housing, the overall precision and matching isn't that good.

[Matt@Cosworth]

Ideally I'd say you want as large a compressor that your motor can spin at a reasonable speed to stand a chance of the greatest amount of mass flow

there's obviously some trade off here as depending on the compressor map / efficiency a 50K rpm compressor that delivers 200 g/sec
may need a lot more shaft power than is available than a 70K rpm compressor that also delivers 200g/sec

however shaft power is something that the turbo manufacturers don't tend to release
probably because its not easy to measure and most folks don't care anyway