I'd like to make an oil pump on my small mill. Its a special project for a car and its okay if it doesn't work right or blows up the engine, the car is practically disposable and is meant for experiments like this.

The rotor design is pictured below. Apparently this is called a positive displacement, lobe style, rotary pump. Its very typical of automotive oil pumps, and apparently, can also be made in aluminum (yes, the rotors and housing).

I'm wondering if anyone knows where I can find the geometry for this style of pump? It looks pretty simple, but I'd rather not guess at it. It must be a very old design, maybe there is some engineers handbook with geometry?

Has anyone made a lobe pump for a mini engine?