[slyalfa]

the turbo feeded a roots has been done many times turbo mag did one a while back where they put v6 into a mr2 and did a turbo feeding the roots. it seems to work out very well.
the turbo blowing into the roots seems to negates any drag. they had the roots going right in no intercooler. but the turbo did. using a large turbo was not a problem as the roots get the boost at idel and up to about 1/2 way. the boosted motor then is making more power at the getgo so there is a lot of flow to spin up the turbo. so the turbo come up much much sooner.

the roots will not spin any faster then it would with out any turbo so overspeed is not a problem.
as for heat when it is not doing any work there is not noticable heat made. in fact it is cooled if anything. if the IC on the turbo is working. but it has to be a roots type if it is the Lysholm type it will not work. as it will recompress no mater what. the roots type do not use a clutch as the drag can go vely low in bypass mode. but the Lysholm has a lot of drag nomater what so they normly use a clutch like the AC has on them.