Hans, when it'* sealed during manufacturing, it hasn't heat cycled, warped, or had foreign material in it.

If your car came from the factory without exhaust manifold gaskets, why do you put them back with them? Same reason.

It'* your car. Follow our advice or not. Your choice.

I'm not interested in "halfassing" the job one bit. I want it done right, however reviewing other resources I did not see that it was required or needed to seal the rotor plate to the rotor housing.

Hans, I don't make idle chat. I've rebuilt how many superchargers in the last 4 years? You really can take me at my word. I don't BS people about anything.

I just think about it this way - you've got two machined surfaces, like any other in the car. Except, unlike other surfaces in the car (almost all of which we take the time to put a gasket on), this one is responsible not only for basic sealing, but for sealing under pressure - typically around 7 PSI worth. Not a whole lot, but enough that if there'* any gap in the seal, you're going to be blowing boost into your engine compartment.

So, for the extra 3 minutes it takes (plus some extra care, as noted above), I don't see the point in not adding the sealant.

And, as a counter point, my blower had evidence of some sealer on this surface when I took it apart... a very thin layer. Very thin. A little carb cleaner and a rag (along with some muscle) was all it took to clean it off... but it was there.

Just my opinion.