2020 Frank Motortechnik
In the past NSU engines have been more a passion than a business. Powerful and reliable engines are very time consuming. Changes in valve size and angle, camshaft bearing diameter, among other time consuming machining, are necessary to achieve at least the power levels everybody is telling from back in the day. But, the parts and their copies from those days are not useful and needed any more. For serious competition modern pistons and camshafts are used. Cam profiles with more than 336° duration are useless in my opinion. 1300 street engines are dynoing at around 100 to 110 HP, depending on the parts. A reliable and “WOT standing “ road race engine according FIA appendix K at around 115 HP. This seems to be extremly low, but that’s the reality from my calibrated engine dyno and not some fantasy corrections done on a chassis dyno with 50 plus degrees intake air temp. In general all engine cases are line honed, rod ends are resized to smaller clearances. With preciser and tighter clearances no big oil pump is needed any more. Required are a good set of TT heads and good set of rocker armes. Everything else can be  refurbished somehow.