Dry sump pump experiences and preferences...

[Shaun]

What are the actual vacuum levels on a good 5 stage spur gear pump versus a 5 stage roots type pumps? From what has been written it sounds like spur gear types pull no vacuum, whereas some offhandedly say a spur gear pump can almost approach roots level vacuum?

I was all ready to buy my pump until a very good builder advised me not to spend unnecessarily on expensive roots pumps. He said it was not needed in my application (endurance road race) unless I had a driver and chassis capable of winning the class - which I don't. The class I intend to compete in is dominated by multi-million dollar big wigs, but we still want to see how well we can do, and how fast and efficent we can get the car. We will have a very good chassis, just not a winning one.

Mentioned also was the spur gear's larger tolerance for debris. This is minor though because ideally nothing should come through.