That's probably because they weren't availible in Japan. Japan didn't use numbers at the end of the motor code except in the very first B16A1 from the CR-X. The closest you could find to the B18C4 (EDM 1.8 vtec motor from the Civic VTi, and the Aerodeck 1. is the B18C from the Si-G Integra, though both are the same spec as the B18C1 from the USDM 94+ GSR's.
Oh, and B16A2's are from the EDM 92-98 civic/Delsols, and the USDM 99-00 Civic Si, both of which where 160Ps/Hp. The 170Ps version was the JDM B16A from the 92-98 civic SiR/SiRII's.
