Hi Guys! We will be having this local sf4 tournament and the venue that we chose has a 51" LCD TV already installed. I’m wondering if it is ok to use that LCD TV or will it produce some frame lags or something? Thanks in advance 
Need more info. What brand and model is this 52 inch LCD TV?
Yes it more than likely produce lag, but both players will receive the same lag so at least the playing ground be even.
Yes, it will produce added frame lag. How much will depend on the model. Once you know what model and brand it is, you can go to displaylag.com and look at the database there to see how much it is. Usually large LCD tvs have hideous amounts of lag, especially 50"+ sizes.
If your goal is to have a serious tournament, then you can try picking up tournament-standard Asus VH236 monitors, or use CRTs.