Engine and aircraft specs
16,000 rpm was achieved with a total pipe and header length of 20 inches. This is absolute optimum, I checked it carefully both longer and shorter. Engine unloads very nicely in the air. Prop was APC 10X8 sport. Magnum 15% fuel and KB1L plug. Every other combination of fuel and plug I tried produced less rpm.
Airplane is balanced at extreme aft end of the range, somewhere between 2 1/2 and 3 inches behind front edge of aft cover (I just use my fingers). Elevator throw is 7/16, aileron 3/8, no expo. I'm not a big fan of expo but don't like a touchy feel either. The throws and CG I am using give a very smooth feel in flight and plenty of elevator authority for landing.
The added weight of the Whiplash is a real advantage in dives, it picks up speed fast and keeps its momentum. So far I really like the airplane. The BSE FIRE 60L is super sweet. Now, if I could just get a couple more thousand rpm...