Crank case breathers aren't great. You were lucky, I blew out the rear main seal. I just made the two cam cover breathers flow as well as they could...ideally you would weld on new larger fittings. I also just ran mine to a catch can with no PCV...so not strictly street legal but solved the...
As a quick check hit the belt with some " belt grip " 1st. Not a long term solution but it'll solve any slip short term and confirm that's the issue. I'm a bit surprised it's slipping as they don't have anywhere near the load of a posi SC and not hard to get them spinning big boost with no slip...
Belt wrap wont be an issue for this....definitely sounds like a leak as boost sounds about right at the compressor outlet and you can't lose 6psi as a pressure drop along the intake...1 or 2 at most unless he's used garden hose ;)
Centrifugal blower Rod, totally different kettle of fish to positive displacement.
I'd guess your BOV is leaking or a leak somewhere. No way you can pressure drop 6psi from SC outlet to TB unless there's a leak or the shittest intake piping ever built ;)
Got a pic of the setup?
Yup sorry wrong again ;) the bypass is vac opened to avoid the SC stretching the air in high vac ie low throttle open positions. You obviously aren't needing boost in those conditions so you bypass the SC to 'unload' it and provide an alternative air path to the engine. Reduces intake temps A...
A roots SC is very very sensitive to any restriction upstream ie if the throttle isn't pretty well full open it won't make boost. If you have just been revving gently at idle its normal not to make boost...it needs lots of throttle :)