If standard flood lights are par38 size, could they be used for show lighting if put in a flood fixture without being an expensive set. they will be up in the rafters where the audincce cant see them.

Also, I am doing an event outdoors in a small pavilion with stage. Should I use lights, I don't think it would even be wothr the time, cause of the sunlight, the light effects may not show up. I just want my illusions to look good.

My short answer is yes...use them...especially if you're going to video your show

It really has to do with how close the lights are to the stage. There's an inverse square law with lighting so you get very little output from those lights if they'e not close to you.

The second issue is the ambient light. It depends on just how bright it is as to the wattage you'll need to cut through the sunlight. If you can, experiment and test a few options or ask the guys that work there what they would recommend. You definitely want to be brighter than the surroundings to keep the focus on you.

Ray is right.
In all reality, though, par 38s are really small, as is. Floods could work in a smaller theater as a quick fix, but you'll get little results in larger venues or outdoors. If you want light during the daytime, you may want to buckle down and rent some (about 4) Par64's somewhere, and a couple of light trees (stands). The rental cost would be about the same as the purchase cost on a few floodlights and fixtures.

Choose your poison.