Along with an increase in compression, what is the best way to improve air/fuel burn & flow through the Mi16 1.9l head-ie: volumetric efficiency?
[The low emission XU9J4Z engines (our Oz versions-cat equipped) have a lower piston crown height compared with the non-cat engines. The piston sits 040'"- or 1mm further down the bore-hence the 9.7:1 compared to the 10.4:1 comp ratio of XU9J4's.]
I'm aware that the inlet cam was also retarded with the 'Z' engines (although this isn't an issue in my situation as I have adjustable cam gears}.
In reference to the lower comp engines, what is the safest minimum squish distance between the piston & head? Component expansion & piston-head collisions are what's at issue here.
I've read that .035" minimum squish seems possible using standard components up to 6500rpm. What about 7500 (which these engines can handle comfortably)?
The cylinder head is recognised as one of the best flowing N/A heads around but can still be improved with porting and bigger valves.
Could the gains from the bigger valves be somewhat compromised by their proximity to the bore causing partial shrouding?
Comments from those experienced in this area of engine performance gains appreciated.