Terry, try changing the pipe length or better still change to a different pipe but keep plug to start of stinger the same length then see if the dip is still there or moved to a different rpm. That way you will know if it is a problem in the drivetrain. My experience is that it is all in the...
Terry, Take care with your automatic needle setting vs EGT. As soon as an engine starts detonating the EGT drops and your system may well lean it out more, and then BOOM.
In Europe virtually all racing surface drive monos 3.5cc and 7.5cc use gearboxes for the simple reason that they are faster than direct drive in the oval races here. The bigger props are more efficient and give better bite in the rougher conditions that we often race in here with up to 10...
On nitro engines....
1. On a rigger the pipe is being cooled by the airflow as you go faster. That is just what you do not want.
2. Pipe design. In general, a short steep angled rear cone will cut off the power after peak. A shallow rear cone angle will allow more over-rev.
On gas...
I have not used a one way bearing on either of these dynos. At first I would blip the throttle when the flywheel was slowing down after a run, but in practice the flywheel disengaged pretty quickly. If there is a brake on the flywheel then it can be slowed very quickly. One of those things where...