Hi Bernie,

 

Generally, using the EC2/EC3 when at idle/low rpm/low manifold pressure (with the default staging point of around 14-17 “ Hg – its adjustable) you are below the staging point and operating on only 2 injectors (the primary injectors).  When a certain manifold pressure is reached, the EC2 activates (or Stages) the two secondary injectors.  So below the staging point you are operating on two injectors and above it on four injectors (except for the three rotors where it’s three and six injectors).  

 

The primary reason appears to be that the rather large (compared to most autos with the same size engine) injectors on the rotary would make it difficult to get a good idle by trying to reduce the activating pulse duration low enough to get just the fuel needed if all four injectors were on line.  Most injectors require around 1 msec or so to open, so pulse durations around or below that just do not give good fuel control.  However, if you chop the number injectors in half then you can double the pulse width putting it into the 1 msec + region which the injectors can respond to.

 

Now some folks have found innovative uses for the staging scheme beyond that.  Dave Leonard creatively sets his staging manifold pressure so that he only stages when his turbo is producing boost.  He flies on only his primary injectors (which provide adequate fuel for unboosted regimes of flight), but when the turbo boost comes on and his manifold pressure gets above ambient at some point then his two secondary injectors come on to provide the additional fuel needed for his turbo boost regime of engine operation.

 

Hope this helps

 

Can someone briefly explain the meaning of "staging point", please?

Thank you, Bernie