We determine elastic constants K-11, K-22, and K-33 in two diphenylacetylene-core-based liquid crystals with azo and ester linkages. As we have already reported (Adv. Mater. (2014) 26, 1918), K-33 is extremely large (sub-nN) compared with K-11 (pN) in the azo compound, since cybotactic smectic (Sm) clusters exist in whole the nematic (N) phase range. As a natural consequence, K-22 is expected to be also large. We confirm that K-22 is several tens pN, which is smaller than K-33 but larger than K-11 by one order of magnitude, K-33>>K-22>>K-11. This is the first compound, which has a larger K-22 than K-11. In the ester compound, which has no clusters in the N phase, all the elastic constants are in a pN range, and are in the usual order, K-33>K-11>K-22. It is also important to note that not only K-33 and K-22 but also K-11 show a pretransitional increase when the N-SmC phase transition temperature is approached.