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  • Supercharger Abuse Question

    I am wondering to buy a cheap used Supercharger from Craigslist and drive it with a 2 hp electric motor as a high power vacuum pump. Vacuum pumps in this power range are normally quite expensive.

    I am pretty sure this will work theoretically but I never had a supercharger (Roots Blower) in my hand and don't know what practical obstacles there are, e.g. How that thing is lubricated or what leakage to expect. I am looking to get maybe 75% vacuum (20-25").

    Any opinion if that could work? Or just a stupid idea?

  • #2
    Magnus is the expert on superchargers but I don't think 2 HP will be enough power to get what you want.

    Why do you need the high power vacuum?

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    • #3
      Hold-down table for my cnc machine (for sheet material). A wimpy pump will struggle with unavoidable leakage.

      The 2 hp motor is a guess. I need to look at some pressure/volume/rpm charts for typical blowers to see if it might work. But I am in Germany right now with only an iPad and a shaky Internet connection.

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      • #4
        I've seen vacuum chucks in use and they don't need a lot of power. I'd look on Ebay for a vacuum pump. If you don't have a leak it will hold it very well.

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        • #5
          I have an 1/3 hp piston vac pump. That is good enough for a vacuum chuck on my wood lathe with a good seal but not for large sheet good that may not be flat and even porous. I have seen professional Cnc clamping vacuum equipment with over 15 hp 380V electrical power. But that is typically for 8' x 4' tables or larger. My machine is a bit smaller and I have anyway only 240V. There is a blower for sale (unknown Ford model) in Azusa for $75 and maybe I just go and play with it.

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          • #6
            What about just using a large shop vacuum?

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            • #7
              Ehm.

              My experience with superchargers are in a purely automotive application. That said, it should work quite nicely as a vacuum . You should also be able to modify a regular air compressor, let it vent to the atmosphere and use the inlet as a source of vacuum. Or, if you want to go fancy, run it backwards and use the tank as a vacuum reservoir.

              /Magnus F.

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              • #8
                Gert

                A vacuum reservoir is a good idea. Brother Tom mentioned that when I asked him how they do the vacuum table at the woodworking shop.

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                • #9
                  Just don't overdo it with the vacuum.

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                  • #10
                    Originally posted by magnusfeuer View Post
                    Ehm.

                    My experience with superchargers are in a purely automotive application. That said, it should work quite nicely as a vacuum . You should also be able to modify a regular air compressor, let it vent to the atmosphere and use the inlet as a source of vacuum. Or, if you want to go fancy, run it backwards and use the tank as a vacuum reservoir.

                    /Magnus F.
                    In principle this is possible, but a regular compressor will vaporize a large quantity of oil when running as vacuum pump and is designed to compress to 150psi. I need only minus 10-12 psi but a higher volume.

                    The dual piston vacuum pump that I have is specially built for this purpose and oil-less (just too small). That is the nice thing about the roots blower since it uses the oil only for the bearings while the rotors run dry.

                    I think I will go a bit smaller than the rail car with the reservoir. Maybe an empty propane bottle or just a length of 6" plastic pipe.

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                    • #11
                      Got my new toy :)

                      Eaton M62 Supercharger off a 3.8l Buick V6.

                      eBay $59 including shipping from Florida. Can not complain about the price....
                      And...the rotors are spinning. I had kind of expected something rusted in place but maybe I can just check the oil level and use that thing without bearing rebuild. I tried it with a hand drill and it pumps quite nicely.
                      Not sure what that little butterfly throttle is about and several small nipples. Probably idle control and vacuum hookup but I can plug them all.



                      Last edited by slomove; January 17, 2013, 08:55 PM.

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                      • #12
                        I got my vacuum gadget running.

                        Good news: it works as expected. I used a 3hp motor from Harborfreight and pulleys to run the supercharger at 2800 rpm. I can get about 15"Hg vacuum (50kPa) before the motor stalls and 10" continuous. Pretty much what I need.

                        Bad news: That contraption would get me black flagged at Laguna Seca immediately. I measured 100-105dBA from 10 feet away and it sounds like an orchestra of powerful thickness planers. There is no way I can run this in our neighborhood without extremely serious muffler. Oh well, one of my fun projects.

                        Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

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                        • #13
                          Great progress Gert. Where is the noise coming from? Is having it mounted on a large board acting as a sounding board?

                          PS: It would make a hell of a flowbench!
                          Tom "ELV15" Jones
                          http://PIErats.com

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                          • #14
                            Dude... that thing sucks! :-D
                            Chris
                            ------------
                            A day you don't go a hundred is a day wasted

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                            • #15
                              Originally posted by Elv15 View Post
                              Great progress Gert. Where is the noise coming from? Is having it mounted on a large board acting as a sounding board?
                              No, that is actually very common for roots blower used for vacuum. I really don't want to hear a commercial 30 hp unit howling.

                              It can not be seen but the mounting board has a 4" by 4" cutout where the exit of the supercharger is. Every time one of the six total rotor lobes comes by with a pocketful of vacuum (so to speak) the ambient air rushes in. That happens 300 times per second making for a fabulous air raid siren. In the meantime I rigged up a temporary muffler with a second board under the whole contraption that sandwiches a few baffles and packing material. That cuts already 15-20dBA and makes it almost bearable. I think with a bit more optimization I can use it without getting tarred and feathered by my neighbors.

                              Originally posted by moosetestbestanden View Post
                              Dude... that thing sucks! :-D
                              Yep, that is the whole idea. But it is surprising how much power is needed to operate it. I bet in its intended use as compressor at full engine speed it can easily eat up 10 to 15 hp before generating anything additional.

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