In Japan, both the 180 and the sylvia had the CA18 which was later replaced by the SR20! Nissan got broke and it shows. Could no longer afford to produce the CA and RB engines, so to cut costs they did away with the rather expensive CA, but kept the RB around. They introduced the SR with bigger displacement, bigger stroke, alloy block instead of cast iron, very cheaply designed head (and it shows) and a slightly better turbo which ultimately equates in the difference in power between the two.
People look at the power differences and displacement differences, but fail to look at the big picture and that is that when they break and they will, which one is going to more expensive or a pain in the ass to repair. The KA24 is a pain in the ass with it's always failing oil pump. The SR's oil pump has a tendency to be weak as well resulting major damage. Both engines were prduced in the same era at a time when Nissan's pocket book was depleted hence the quality of the parts suffered as well. Timing chains were used on both the KA and SR whereas the CA used a belt which is reliable and very easy and inexpensive to change.
CA18DET=175hp, SR20DET=205 and the KA24DE=155hp! For the quality and compared to SR20DET, I'll happily take the 30hp difference because with the money I'll be saving by buying the CA, I'll make up the difference easily with upgrades (Oooops, already did that ). All of them have their advantages and disadvantages just depends on what you want. Street power, take the SR20DET. Torquey street power, take the KA24DE and boost it and for the ultimate in high revvin, highway cruising, top end loving adventures, the venerable CA gives you the real racing engine sound and feel as well as performance