Thanks Keith, yes 100 ci is what I was thinking in regard to capacity. The point of inlet and exhaust port relate to the position in the charger barrel where the ports need to be machined apparently not exactly diametrically opposed this is due to noise levels and efficiency.
Rob
One of the features of vane type blowers is the fact that they have their own internal compression ratio and therefore the exhaust port opening point isn't really critical. So long as the port has sufficient area for good flow and it closes when the segment between vanes is at its minimum volume it will be ok.
The intake port generally will have a longer duration - theortically it would open immediately after reaching minimum volume and close upon reaching maximum volume. In practice you'd want to delay the opening - the internal compression ratio mentioned earlier means that there will be some "trapped" pressure so in the interests of noise reduction the chamber is allowed to expand somewhat before the intake opens. If you use peripheral ports one of the challenges will be maintaining even wear of the vane tips.
Most vane type blowers/motors use phenolic or carbon vanes; some like the old Shorrock used a complex system to maintain a small clearance between the vane tips and the housing. Vane blowers were always regarded as being a bit less efficient than a Roots blower; I'd expect a modern Roots design such as an Eaton to be quite a bit more efficient. Sounds like an interesting project though..
