Hello there. Have a 1980 930 upgraded to a 3.4l twin turbo. Car was running 215KW on the wheels at 0.5 boost. Had a few problems with the injectors, distributor, filters and fuel mix and had them sorted. Car  was then running 260kw on the wheels at the same boost. Increased the boost to just short of 0.9 and the car was showing over 300kw on the wheels before the clutch broke. Not to sure at this stage what in the clutch actually broke, mechanic having a look. Now I'm still using the 4 speed 930 gear box and as far as I know original clutch. My question is this: I obviously need to look at a stronger clutch (or maybe not) but what would be the best option here. Any suggestions?  Thanks

Sounds like the OEM clutch just doesnt have the clamping force needed to do the job.  Will be interesting to see what your mechanic finds when he strips it down.

Sachs do a good power clutch and if not there are quite a few other clutched systems around which have plenty of clamping force.

The trick is to try and keep the rotating mass to a minimum while getting adequate clamping force.....