Homemade Roots Blower: Second revision of the rotor profiles

Hopefully This will be the final designs of the Roots lobes before I start making it.

I decided to design a 3 lobe and 2 lobe rotor that would be compatible with supercharger case I designed, I will see which works out best by testing it in use. I will most likely make the 3 lobe first since I feel that the 3 lobe design is better.

I do not have any keyway broaches, for now I will just have drilled holes for the keyways. I plan on using a 1/8 round nose endmill to cut grooves into the shaft so that i can insert a 1/8 inch metal rod to lock together the rotor and the drive shaft. No idea how well that would work out though.

This 3 lobe is significantly smaller than what I had originally planned mostly due to the size restrictions of my small mill. The entire assembly is much smaller too.

Some advantages I see with the 2 lobe rotors is using less raw materials to make one and less machining required. Unlike the 3 lobe above, the centers of radii is different between the male and female lobes. I designed it this way because when they are equal, the center section becomes too thin to properly support the rotor.


I also made a rotor profile that just looked like an oval blob, was surprised that it actually works but the swept volume was very low so it's not very practical.

Next I will probably try to make a lysholm style rotor.

Homemade Roots Blower: Almost done with the design

All i need to do now is print out the drawings and cut a prototype out of plastic or some type of hardwood.

I think my next few posts will be the drawings/blueprints of the individual components. 

If I make this out of wood I would probably just print out the drawing, glue it onto a block of wood and jigsaw out the profile of the part.

If I am to use this as a supercharger as originally planned, this would need to be made out of aluminum at least... as I'm sure gasoline and wood does not mix well especially if I am trying to keep close tolerances on the wood.

Whipple Supercharger W140AX Sight Glass Cleaning

I usually change my supercharger oil whenever it turns really dark.
The last time I changed the supercharger oil I noticed it was getting hard to see the oil level through the sight glass.

... this time when I went to change the oil, this is what i saw

I could not see anything at all, even in bright sunlight and using a flashlight all I could see was blackness. The supercharger gear case could have been empty for all I know.

Not knowing the proper way to clean that sight glass or even if I could remove it or not, I did not want to risk damaging anything or risk knocking my car out of commission so I decided to contact Whipple Superchargers and ask them what I could do.
Their response was:
"You can unscrew it to clean it. There is an o-ring seal behind it that is reuseable. You will need a 23mm socket and it will need to be ground or machined down to clear the cover."

They are right about the clearance issue, none of my 23mm sockets would fit it, and I did not want to mar it or risk stripping the nut with pliers or a wrench. The sight glass looked like it was made of aluminum and expensive to replace too.

I then went out and bought a cheap 23mm socket to grind down... I did not take any pictures of the unground socket but I'm sure you all know what a normal socket looks like.

But a ground socket looks like this

I think i did a pretty good job, though there is a slight taper to it probably due to my lack of grinding skills...

... it still works though, thats all that really matters.


I decided to measure the outside diameter of the ground socket

The diameter of the ground socket came out to around 1.151 inch.


Now back to the supercharger, not knowing how much oil was in the supercharger I decided to drain it all using a very crappily made suction/vacuum thing.

Removing the oil fill plug was probably the easiest step

I noticed that the o-ring seal was cut by the threads.

I will probably have to replace that o-ring sometime in the future


In goes the suction hose and out comes the oil

After all the oil was sucked out, I replaced the plug due to it snowing a bit outside and I did not want anything getting into the supercharger.


Now it's time to remove the sight glass with my newly ground 23mm socket.

It came out rather easily.


It looked dirtier that I expected

There was black film of something sticking to the inside of the glass...

You can sort of see through it if you brought it up to the light.


But if the background is dark...

A view inside

Dug out an old can of carb cleaner to wash the sight glass off

It takes a lot of carb cleaner to spray all the grime off both sides of the white plastic part

Finally it is clean

Time to screw the sight glass back in

Not too tight due to the aluminum threads and o-ring seal

This looks almost like new

I refill my supercharger with GM Supercharger Oil

Filled to the halfway point according to the manual.

This is what it looks like with the engine running.

DIY Roots blower: Blower case and animation

So my previous posts was about blower rotors and how I might make them, now I get to put those rotors into a case. It is a rather simple case, but I am trying to make the construction as simple and straightforward as possible when I start making it out of wood later on. This is a primarily designed as a kind of DIY home made supercharger, not something you would bolt into your car.

And this is how it looks assembled

Since I have it all assembled, might as well make a animation of it...

DIY Roots blower: rotor profile drawing/dimensions

I set up this CAD drawing for spacing the rotors 2 inches apart. But when i actually make it out of wood, I think I will resize the dimensions so I can reuse my hole saws from before. Trying to find .518in radius I.D./O.D. hole saws would be too difficult... With this base drawing I should be able to scale it up to any size i want.

Roots Supercharger Rotor Profile

I wanted something simple so I wanted to see if I could make the classic roots rotor profile in cad. Doing so I discovered why my wooden rotors didn't mesh properly. I totally cut the rotors wrong, but the proper profile also seems rather simple to make.

Now this looks much better, I'll post the actual dimensions and drawing later...

Even though I designed this in a CAD program it still seems like it would be possible for the layman to make a real supercharger.

Rotor profile fail...

Apparently having symmetrical and perfectly round lobes does not work as the lobes will not mesh correctly. I will try to design a simple to make lobe profile in Autocad before I try again to make another set of roots rotors.

Making a DIY homemade Supercharger

Originally I wanted to make my own small engine supercharger. Or at least find out how difficult it is to make one. There are other alternatives for small engine superchargers such as smog pumps, crankcase vacuum pumps, and the chevy oil pumps. But all of those would have trouble supplying a decent amount of pressurized airflow to a small engine.

I think a small roots type supercharger would work out nicely for a small motor, but the thing is that there does not exist any. So i decided to make my own.

After some planning and drawing diagrams on random pieces of scrap paper i realized that it isn't as difficult as originally planned. the rotors are actually quite easily made. The only hard part is attaching the gears to the thing, because currently i have no ability to make gears.

I decided to mock up some blower rotors in wood first as an experiment to see how easily i can get it to somewhat resemble an supercharger.



Making that was surprisingly easy, all i needed was 2 hole saws for the inside and outside diameters. I cut out cylinders with one hole saw and used the other hole saw to notch the center part for the rotors to be attached to, basically 6 equidistant notches in a circle made the center part. Looking at this design i realized i could just use a hole saw to cut out the center part from a plate of metal and then weld/solder/braze/glue cylinders of tubing onto the center, and i would have some easily made roots supercharger rotors.
I could extend this step to make rotors as long and big as my drill press could handle, could be an interesting project later on when i start making them for bigger and bigger engines.

Now the next step is making some gears to prevent the rotors from constantly grinding each other. The rotor case should be easy enough to make, using a fly cutter to bore a hole. Making gears is the hardest thing for this project. I will try to make some gears from wood as soon as i get some gear tooth cutters.

My emphasis here isn't really on precision, mostly the bang for buck rating. If I can make boost on a wood roots blower i would use a wood supercharger hehe. Of course if the wood one doesn't last as long as expected then i would try to remake everything in some other cheap material such as plastic or mild steel.

Turbocharged Gas powered skateboard

A gas powered skateboard is nice... but not nearly as nice as a turbocharged gas skateboard. The skateboard comes with a 52cc 2 cycle engine usually used on tiny underpowered scooters, which is not nearly as powerful as it should be. So of course I will need to increase the power.

Originally I was thinking about using a small supercharger for the skateboard, a supercharger would probably be easier to install in this application, no ducting needed for a total smaller and lighter package. Because they do not make superchargers small enough for a 52cc engine I would be using high flow chevy oil pump. Those gear pumps act in the same way as positive displacement roots pumps, and since there would be 2 cycle oil in the gasoline, lubrication wouldnt be an issue with the gear pump.

In the end i decided against a positive displacement blower for the skateboard because 2 cycle engines need something akin to backpressure to function properly unlike 4 cycle engines which works better without any backpressure. If i was using a lot of supercharged boost, the pressurized intake charge would just blow out the exhaust and i would need some type of exhaust restriction to prevent that from happening, even a standard 2 cycle exhaust waveguide/resonator would not be able to create enough pressure to keep the intake charge in the cylinder. So if i was gonna use the exhaust restriction method then might as well use a turbo to use up some of that exhaust pressure.


Which led me to the purchase of a Mitsubishi TD02 turbo off ebay.
Some people might be thinking, wait a second, 2 cycle engines dont have pressurized oil, how are you going to keep the bearings alive. Well sleeve bearings dont really need pressurized oil to function, of course having pressurized oil would be best but im not aiming for a 100,000mile before rebuild lifespan from this skateboard. Have you ever looked in a lawnmower engine or something like that? Those use splash lube for everythign and it runs fine. I will also be using heavy weight quality synthetic oil to keep the bearings alive, like 50+wt oil.

I might also be adding on nitrous oxide for added horsepower in the future if the turbo is not enough. But i would need to upgrade the engine internals before that.