I dont know in these games but is is usually a command you type in the console,like in Quake for example.In Q3,first version,you type:"r_swapinterval 0"
"timedemo1"
"demo demo001"
try to look in the games manual.
here is a little program they told me about at via ,it counts frames in the game.Havent tested it though.
link: www.fraps.com
have fun,be lucky