At 10:48 PM 12/12/2015, you wrote: >Concerning Dual ignition: I also get 100 rpm more with both ignitions on. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
The reason for an rpm increase is because two plugs firing in the cylinder gives a better flame front and thus a faster burn. Once the cylinder volume reaches a certain size, adding a second plug will increase performance. That's the primary reason we get a drop in rpm when doing a mag check with aircraft type engines. I'm not certain if the VW's reach that cylinder volume or not but I suspect they do. The other critical variable is spark timing. Electronic ignitions with variable timing can be adjusted for best performance at higher rpm's without creating problems at idle. Larry Flesner
