In order to further improve the aforementioned operations, it is preferred that {HEAD ~ an opening area} of the first intake air passage is reduced and {TAIL ~ an opening area} of the second intake air passage is enlarged 
In order to further improve the aforementioned operations , it is preferred that { HEAD ~ an opening area } of the first intake air passage is reduced and { TAIL ~ an opening area } of the second intake air passage is enlarged
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH