used centrifugal blower - looking for one in Australia

[49-1183904562]

Ok Tony i am going to go way way out on a limb here but I recall a post where Doug (slracer) was working on a home built super charger project for his small-cc Honda (Auto Air Pump). How feasible would it be to do something like this (centerfugal blower) in say a coffee tin diameter? could it move enough air? or make enough pressure say 10" I think he is like 100cc or 6cid. He would need only 20 couple cfm max and could spin it at say 2 x rpm so 14000 to 18000 rpm ??? i know he was not looking for big boost i think he was sort os looking to offset the altitude at the lake.

I told you I was going out on a limb here so be kind to my D__b A_s

Rick



Edited By 1960FL on 1254577004

[slracer]

Hi all, Like many of my projects, the supercharger is on hold until I finish the new bike frame. The auto air pump is no longer on the parts list. One of the forum members had some "broken" turbo parts so I wrote to him. He decided the broken pieces wouldn't be a good fit so sent me a T-03 wheel and some of the scroll parts. I did my sizing exercise and that wheel is still to the left of the map so have been trying to decide how to make the wheel smaller and turn it a bit tighter (something like 81,000 rpm). It looks like a small gear train with 2 steps about 3:1 each would work well and actually fit inside the stock engine casing if I'm careful. I won't name the "guilty" party, but Thanks Tom! it's still in work.

I think it was Tony who offered a book for centrifugal fans for home building in one of the first posts I saw here. I bought the book and it is easy to understand and figure out what it takes to design and build your own fan. It is called "How to design & build centrifugal fans for the home shop" by David J. Gingery. I got it through Amazon.com for about $10 +s&h. It won't make you as smart as Tony, but it will help. In a turbo thread (which I can't find right now), I posted a website of Garrett(?) which has a section called Turbo 101 (or similar) which went through the steps to size (or check the size of one of their turbos) vs your needs of boost and flow. Another learning experience! -- Off to Bonneville in the AM so off will be off line for a week (or more). Morning temps on the salt are mid-40's and some rain is predicted so it may be a long "Sunday" drive! -- Doug

[jfholm]

[color=#000000]Doug,
Thanks for the link. There was only one new one left for the 9.95 so I snagged it. The rest are used copies and they want a lot more money for the used ones, go figure. Good luck on the trip and be careful. Wear a good coat it has been cold. Yesterday morning in SLC it was 35

[tweaks]

Thanks for that bit of information Bruce I will go back looking for a blower around here and if worse comes to worse will get and build one ..laser cut the components and weld them up in shop ....
I am wanting to test up to 50 inches as I do mostly 4 valve Honda engines

Cheers

Lynds

[jfholm]

I received my book on building your own fans today. I looked in it and was looking at building one with a rotor 36" in diameter and 1" wide.

Using the formulas in the book it figures out to be 1105 cfm at 1765 rpm and 17.6" h2o.

Is that unloaded pressure, 17.6" h2o? Would it be capable of more pressure if I only was flowing 600 cfm?

The book also said that 6 hp would be needed but I was looking at 10 hp motors on ebay. Most are 3 phase. I only have single phase at my house. Now haven't we discussed a device to run 3 phase on a single phase system?

Thanks,
John

[Tony]

[jfholm]

Thanks Tony,
Your answer is right what I was figuring from the book. To get more pressure it said I would have to spin it to 3000 rpm but than that would be 30+ HP and that is "BIG". That would give me 51" H2O. and 1877 cfm.

I was hoping it would give more pressure if I was asking less cfm from it.

btw I found the article on running a 3 phase with single phase by using a converter or transformer.

John

[jfholm]

I found a size that might be be a workable deal. 24" rotor 2" wide. If I can spin it at 3500 rpm that works out to 31" H2O and 1952 cfm. That would take 20HP.

That might just work!

John

[Tony]

Again, that sounds about right John.

I have not seen that book, but it sounds like the Holy Grail.
It might be worth promoting it a bit more on this Forum as required reading for big blower freaks.

As I suggested earlier, when searching junk yards, look for something with about a 36 inch diameter (900mm) outer casing. It will probably have about a 24 inch diameter (600mm) wheel inside. That will put you in the required pressure range with sane motor rpm. And something three feet in diameter is just practical to fit inside a bench and have a convenient work height.
With a 10Hp motor, (or better) should put you into the race with about 500-600 CFM at usable flow bench pressures.

A 20 Hp motor should be good for around 1000 CFM + with the same diameter (but wider) wheel, and wider outer casing, and correspondingly scaled up inlet and discharge flow areas, maybe six inch inlet and four or five inch outlet, for a six inch flow bench test hole.

These type of threads are good, because it helps people to get the "eye" for what might be an ideal bench blower, just by the shape and dimensions of the outer casing, and diameters of the inlet and outlet. Something around four inch inlet and three and a half inch outlet might be about right for most of us that run a four inch flow bench test hole.

You can usually slip a steel tape up through the intake of a junk yard blower to measure the wheel radius, and look through the discharge hole to judge wheel width.

If you can find an ideal junk yard blower, it will probably cost you less than the steel to build it.
The motor can always be changed, but a well sized rotor and housing are pure gold.

[Greg]

Going on with my centrifugal blower upgrade, I'm looking around for a vfd now to run the motor. Would a vfd that is rated for a 45kw motor work properly on a 10kw motor? I know nothing about them, have just seen some bigger ones for sale that seem to be going cheaper than the small ones.

[Tony]