(Grob 2500 Engine
For Grob engine read VW type 4.
Limbach were 'converting' VW for years with all consumable parts available (and to a very high spec).
The LAA have already confirmed they will have no issues certifying these engines or being able to oversee 'zero timing when required'.
Just to remind people that when Rollason at Croydon produced their range of Ardem VW engines 1200-1600 cc in those days ALL the parts came from the local VW dealer in Croydon. These were the engines that powered the original ATC ( Motor Falkes) and in many cases are still going well in their original airframes. So there is nothing too difficult in the original engine situation if operated under the LAA system. In fact considering the original 109 was designed as a TOURING Motor Glider not a circuit basher, I think that rather dispels the myths regarding engines, and in most cases the aircraft were operating at a higher all up weight than originally designed for, which shows how well it coped. IRMC.
Of course it is not surprising that the VW engine converts so well as its origins stemmed from its 'aviation led designer' which it why it was so light (Mag crankcase) and if correctly cooled (cowled) and keeps its oil coolers performs so well. The 'Hot Ship' VW engines used lightweight Porsche barrels with chrome bores.