Search engine Inside the site

Hello

I need a php script or any type of script that is a search engine that searches inside the site and also get searches from the forum
Any available? I tried a script from here that is on Scripts section i can`t say the name of the site of that script because is one of the rules here Not posting any site. If Anyone knows please contact me sending a private message of the site where can i get it.

oh btw tried google search engine and it is not good they just put a search like: site:nameofthedomain
and it will not get good results
The SE that i tried is manually, but need one automatically.
Thanks