No. The R18 GTS has a similar non crossflow pushrod head to the R16 TL.Ray Bell:
Isn't the 18 an overhead cam engine?
I've been told that because the R18 head has much smaller combustion chambers than the R16TS/R17 crossflow heads, that if you fit a crossflow head to an R18 with the stock 18 pistons, the compression will be alot lower than an R17.Simon:
Another thing worthwhile checking is piston clearances. The 77mm bore 16TL has different pistons to the 77mm bore 16TS/17TL for the purposes of clearing the valves. Not sure how the 18 compares being the 79mm bore as opposed to the 77mm bore.