I am looking to get any and all recommendations for a small, very fast spooling, 48volt electric turbo to feed into a larger turbo in order to increase response and spool a 2.0L engine faster

 

I don’t know any info on the new electric turbo stuff. I’m sure it’s gonna be expensive since you’ll need a 48volt battery etc . You could just use a smaller normal turbo and be done with it and enjoy driving your car.

 

These guys look like the real deal - no outrageous claims. Their 12v model should boost an engine to at least 100 hp before it runs out of puff. https://duryeatechnologies.com/duryea-electric-supercharger/ More than that and you are definitely looking at a higher voltage setup like Torqamp. This guy
built an electric supercharger with a 20 hp motor over many videos. It is a huge task.

You also need to think about which compressor goes first in your compound setup. In most cases I think the electric supercharger should be closer to the engine.

 

Larger of the compressors is the atmosphere (primary) , smaller is nearer the engine (secondary). You want the primary to supply roughly double the mass as the secondary.

 

Of the setups ive seen use an electric compressor, there was valves involved so the electric was for low speed quick boost and when the turbo came on line it would transition valve open and closings to have seamless boost.
Pretty sure bmw has done this on some cars in the last few years.

 

If the electric is a centrifugal compressor, there is no reason the turbo compressor can't simply blow through it once it takes over, with the electric motor switched off or idling. Makes things a lot simpler.

There are a few companies starting to use Garrett's e-turbo concept. MB will be first some time in 2021. Think normal turbo with electric motor/generator between the turbine and compressor. https://www.garrettmotion.com/electric-hybrid/garrett-e-turbo/

 

The motor in the video above is a brushless inrunner motor. There are a lot of them in the hobby RC world, specifically I know of a company called Neu motors that will build custom motors to your specs. I have a friend building a prototype project and the neu motor he used was around $350. If you are serious, having a motor specialist spec the motor would be a huge step in the right direction.

The other part to consider is a brushless motor needs a special motor controller to work. A normal brushed 2 wire motor spins with a steady voltage applied. Brushless motors are 3 wire and need to have the power switched at the correct time to make the motor spin. Google "brushless ESC" and you can find more info on these.

 

I looked at the Neumotor website and they didn't have a motor comparable to the one in the video. The closest I found was 7 kW (10hp) and max rpm 60,000. So yes, you would need a custom build.
60,000 rpm would be needed to get 5 psi on say a GT3076 compressor wheel. To bring electric motor speed down you need a wheel with larger tip diameter without increasing the inducer diameter.