Happy anniversary.

 

Knight is working on a centrifugal design. If his roots style was half the price of a traditional turbo he may have been more successful. His electric units are not worth the price...maybe his kit in development will be.


A 100,000 rpm dc motor attached to a compressor...diy?

 

Woohoo

 

It sounds easy but when a shaft spins at 100.000 rpms, the slightest imbalance will very quickly destroy the bearings. I don't really have the precision equipment to make it work.

 

It would have to be dead nuts to work.

 

If rotrex units weren't so expensive they would be a great choice.

 

Well, I've got a gutted t25. Let's strap a motor to it and see how long it lasts.

 

Do it.

10charx

 

Things are not looking good. The cheapest suitable motor and controller I could find is $450 and not justifiable for a shiggles project. However I have learned in the process that a Dyson moves 30 liters a second at 4.3 psi. (~65 cfm) so with 3 dysons and a power inverter I could move 195 cfm at 4.3 psi which is exactly right for the fit with just a little extra capacity. Is there like a graveyard for dysons? Each dyson draws 12 amps. With an 80% efficient power inverter I would draw 431 amps from the battery which it is rated to sustain for 30 seconds. But the cca test allows a drop to 8 volts so that's really 646 CCA which even my current battery isn't rated to. There's a time to admit defeat. That time is now.


P.S. Hooked my 12 amp shop vac up and it generates around 1.5 psi up to about 150 cfm. I'm seeing a very distinct relationship between pressure ratio, air flow, and power consumption. Is there like an ideal fan law?

 

Well sort of. But you are also forgetting compressor efficiency. How much is that air getting heated up to reach those meager boost pressures with such low mass flow and high draw rates?

Alot of that has to do with the compressor style.

Also, even with 3 dysons humming away you wouldn't see that theoretical 195cfm @ 4.x psi. It is also important to note that the dysons are designed with creating a low pressure zone and not a positive pressure on the otherside of what you are planning to use as a compressor. Reality just hates electric supercharging. Look at what happened with the BorgWarner eBoosters. Nothing. At least so far.

To keep any sort of appreciable boost up with a significant volume flow takes nearly exponential increases in energy.

Effective FI requires a metric fuck ton of energy in some form or another, so you might as well use the otherwise wasted exhaust gasses.

I know, I'm a broken record lol Had I the time and resources I would love to throw some of my thoughts into developing such a device, and I have a few multi-stage axial compressor/brushless DC designs that I feel could work, but they would be prohibitively expensive for your average FF member.

Would you like to borrow my 60lb 1520CA Braille Endurance AGM?

 

I filled up the gas tank $35.00/10 gallon

 

These are the things that go through my brain as I try to go to sleep:
12.4 Multistage Axial Compressors

Where you have the compressor stages and stator fins creating a pressure differential all while the volute is tapering down to keep velocity up.




This is what it looks like when represented with the pretty colors of computational fluid dynamics:


When torque and angular momentum are of the same sign then work is being performed on the fluid, in this case air. In this case velocity would be increasing due to the torque provided by the DC motor creating a compression.

This compression also relates to the temperature ratio across the the stages, which can be quantified through the euler turbine equation, which for my convenience will be using a perfect gas constant:


I feel that this setup, on an appropriate scale would allow for more reasonable levels of energy consumption in driving an electric FI device. One that would provide the volume/mass flow required to feed an appreciably large IC engine and boost output and efficiency.

Though it should go without saying that brake specific fuel consumption would have to increase with boost/rpm to keep detonation at bay..

*brain explodes because its 3:15AM*

 

Also, we probably don't need many stages, nor a particularly large compressor unit when done this way.

So who wants to give me their car and money to make it more better?

 

A Dyson motor is a brilliant idea...some of them do produce 100,000 rpms. A Dyson motor can be had on ebay for around $60.

 

dyson vacs aren't that great. i speak from experience. i dont think it's worth the 400 or watever i paid a few yrs ago.

it's a durable unit though.

as far as GE... done absolutely nothing today.

 

I'll guarantee you a dyson won't do it.

 

If we are looking for an occasional boost of air via electricity, would a large volume air compressor do the job?

 

You need something that can sustain a volume of air greater than the engine can ingest at WOT.

So maybe if you don't mind towing something like this around:
COMPRESSOR, AIR, 60 HP, COMPAIR, SCREW, 250 CFM, - M&E

But that would offset any performance gains lol

Boost is a measure of restriction, so you need to be moving more air than would otherwise fit.

 

Which is why I went and typed this up to illustrate an idea of a relatively practical way to do it in a compact package...

This way you would just need an HO alternator, a single brushless motor and a bunch of heavy gauge cable.

A 12A vacuum motor isn't gonna cut it.

 

You'd only need to tow that around if you wanted constant boosting. That said, now that I have a scratch piece of paper:

An 60 gallon tank filled to full @155psi would give you ~77f^3 at 19 psi. knowing literally nothing about the situation, I estimate that'll give you at best 20 seconds of boosting at 4000 RPMs. practical limitations will cut that even worse, even if you could get valves and piping for that. Weight trade off isn't worth it at 200+ lbs just for the compressor + tank.