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Daeldalus
Daeldalus Reader
1/25/20 3:33 p.m.

As the title states.

I had a crazy idea to find a cheap junkyard supercharger and mount it to a stand with an electric motor and some custom piping to make a shop fan or maybe just a desk fan.

 

Main questions are; would it put out enough air to work? And how big of a motor would i need to run it?

 

Anything else i would need to consider? 

alfadriver
alfadriver MegaDork
1/25/20 4:18 p.m.

The compressor side of a turbo would be more effective.

Daeldalus
Daeldalus Reader
1/25/20 4:29 p.m.
alfadriver said:

The compressor side of a turbo would be more effective.

I have been tossing that thought around too. Main problem i see is finding a way to drive it without having fabricate something difficult.

 

The other reason i am leaning towards a supercharger is because i think it would look cooler. If i am being honest the look of it is like 70% of the reason i want to try this.

_
_ Dork
1/25/20 4:32 p.m.

In reply to Daeldalus :

Just weld the shaft of the electric motor to either shaft of the turbo. You won't have to spin it very fast. But I think a novelty desk fan is the best you'll get. A shop fan puts out a wide area of air displacement. A turbo or super will have a tiny 2-3" hole it forces air through. 
 

you could just buy one of those eBay "electric super chargers" most of the work is done for you. 

Daeldalus
Daeldalus Reader
1/25/20 4:44 p.m.

In reply to _ :

I could always do both a turbo one and a supercharger one.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
1/25/20 4:54 p.m.

You can figure airflow pretty easily - they’re usually rated in how many cubic inches they move per rotation. Then multiply by your motor speed and voila. You have cfm. Or more accurately, cim. Don’t get too excited until you’ve done the conversion :)

Most (all?) positive displacement superchargers pump out the bottom, though. You’d have to put some thought into how you’d redirect that airflow, but you could disperse it at the same time. 

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
1/25/20 4:56 p.m.
Daeldalus said:
alfadriver said:

The compressor side of a turbo would be more effective.

I have been tossing that thought around too. Main problem i see is finding a way to drive it without having fabricate something difficult.

What you’re looking for is a centrifugal supercharger :)

Daeldalus
Daeldalus Reader
1/25/20 5:04 p.m.
Keith Tanner said

What you’re looking for is a centrifugal supercharger :)

I thought about that too. 

 

You have one that you are willing to part with for less than $100? They tend to be the deep end of the money pit for this idea.

Mr_Asa
Mr_Asa GRM+ Memberand Reader
1/25/20 5:06 p.m.

Fun fact, Roots blowers were originally used for air pumps in industrial applications, so you'd actually be using one for its original use.

boulder_dweeb
boulder_dweeb Reader
1/25/20 5:11 p.m.

The answer is yes.....but it would make a better paperweight....

PIcs or it didn't happen! (Grin)

Rog

Daeldalus
Daeldalus Reader
1/25/20 5:18 p.m.

After a bit of research. 

Avg desk fan cfm. 200-800 cfm

Eaton m90 cfm. 125-575 cfm

Holset hx35 cfm. 574 cfm

 

Seems workable even if a bit on the low side. I obviously cant run them near their max cfm ratings because of cooling issues.

 

Though i do have a little physics trick i can do to up the cfm right at the end.

Cooter
Cooter UltraDork
1/25/20 5:23 p.m.

You really should look into how fast you need to spin it and how much horsepower it will take to spin at that speed.

Daeldalus
Daeldalus Reader
1/25/20 5:31 p.m.
Cooter said:

You really should look into how fast you need to spin it and how much horsepower it will take to spin at that speed.

I can find the speed very easily. I have already been looking at some numbers for that on the m90. I am not quite sure how to figure the hp though. For one thing it should be quite a good bit less for this application than for cars because there wont be any load. Also, the PSI should always be very close to 0.

Mr_Asa
Mr_Asa GRM+ Memberand Reader
1/25/20 5:33 p.m.

In reply to Daeldalus :

In reply to Cooter :

In regards to heat and HP, wouldn't the fact that its not pumping into anything negate a lot of that?

ChasH
ChasH Reader
1/25/20 5:57 p.m.

A desk fan is much quieter, if that's a consideration.  Likely cheaper and easier to install, too.

WillG80
WillG80 GRM+ Memberand New Reader
1/25/20 6:19 p.m.

A roots or any PD type supercharger won't have to spin nearly as fast as a turbo to hit max cfm. What's max rpm on a turbo? 50,000 rpm?

rob_lewis
rob_lewis UltraDork
1/25/20 6:20 p.m.

Whichever route you go, you'll need to figure out how to oil it.  I'm not familiar enough with either to know if you just plumped an input an output line and route them through an oil can if the spinning motion would pull the oil in to keep the parts lubricated.  Or, if they need to stay pressurized to keep from seizing.  If you can figure it out, I'd look for big turbos off diesels or something (i.e. less "popular" and the most airflow) to use.  If one isn't enough, you could fab up a bracket to run two off them off the same motor for more (not faster) airflow.  You could use that bendable exhaust tubing on the outflow to point the air to where you want.

Or, get really silly and run it off a small gas motor like a Briggs or one of these.  :)

-Rob

Daeldalus
Daeldalus Reader
1/25/20 6:32 p.m.
rob_lewis said:

Whichever route you go, you'll need to figure out how to oil it.  I'm not familiar enough with either to know if you just plumped an input an output line and route them through an oil can if the spinning motion would pull the oil in to keep the parts lubricated.  Or, if they need to stay pressurized to keep from seizing.  If you can figure it out, I'd look for big turbos off diesels or something (i.e. less "popular" and the most airflow) to use.  If one isn't enough, you could fab up a bracket to run two off them off the same motor for more (not faster) airflow.  You could use that bendable exhaust tubing on the outflow to point the air to where you want.

Or, get really silly and run it off a small gas motor like a Briggs or one of these.  :)

-Rob

I have thought about that a bit too. I was thinking that since i would likely be running much slower and cooler than a car that i could just cap off the oil ports and fill the case partially with  self contained supercharger oil. 

If i find out that that plan is unlikely to work then can run a small electric oil pump out of separate sump i make. I shouldn't need very much pressure to make it work i think.

 

Any other ideas?

grover
grover GRM+ Memberand HalfDork
1/25/20 8:20 p.m.

In reply to Daeldalus :

How about a used pool pump electric motor in some sort of cooler to keep it quiet with a flexible drive coming out of it? 

Woody
Woody GRM+ Memberand MegaDork
1/25/20 8:52 p.m.

Two words:

 Nitrous. 

Daeldalus
Daeldalus Reader
1/25/20 9:05 p.m.

on a related note.

 

would anyone happen to have an eaton m90 they would let go of for cheap?

or a large turbo?

dculberson
dculberson MegaDork
1/25/20 9:20 p.m.

In reply to Daeldalus :

Depends on your definition of "cheap." I have the M90 from a Bonneville SSEi that I'll be selling soon. I don't have a price in mind yet. Looks like they sell for about $150 on eBay. What qualifies as "Cheap" for you?

Daeldalus
Daeldalus Reader
1/25/20 9:28 p.m.

In reply to dculberson :

U pull it yards sell them for around 60$. So that cheap or better. I may just have to go junkyard hopping

Mr_Asa
Mr_Asa GRM+ Memberand Reader
1/25/20 9:30 p.m.

Random thought, ever looked at how dyson bladeless fans work?  Fan blades are in the base, and flow out through the top. 

Hollow it out, use a computer fan on the intake side, and point the pressure side at you.

 

Dyson

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
1/25/20 9:41 p.m.

Roots blowers are usually self contained with no external oil supply. They cool from airflow - and since they're blowers and not compressors (like a twin screw) they shouldn't get too hot in free air. 
 

The problem of scaling up motor RPM to turbo RPM is exactly why centrifugals have gearboxes. And turbos definitely need oil circulation. 

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