Good news and bad news.
As the mean effective pressure has increased through changes in timing a new problem has arisen.
Preignition!
The in-chamber testing can show us the beginning of combustion pressure from the small ignited kernel of flame front, but it is so small at first that the pressure change usually only shows an increase after about 5º of eccentric movement (15º BTDC advance starts showing pressure at 10º BTDC). Imagine our surprise when we started seeing a pressure rise starting at 28º BTDC!
The crazy thing is that it made more power and no real detonation!
Barry
