but why naval variant using inferior Engines(WS-21) as compared to land variant(WS-19).. this doesn't make sense to me.
WS-21 itself an advanced machine but inferior to WS-19.
He stated that although the J-35A incorporates many low-end configurations, it used the WS-19 engine during the September 3rd military parade, which is considered a high-end configuration. He also mentioned that the initial batches of the J-35 were equipped with the WS-21 engine, but did not explain the reason for this.
I would suppose that reliability and stability considerations for carrier-based operations play key roles in the current arrangement of having WS-21 powering the J-35 instead of WS-19, given the greater constrains and stricter requirements for carrier-based operations than land-based operations.
Either way, I think the early J-35 units flying with WS-21 is still a rather good thing, rather than having to stick with the old a$$ WS-13.