box enclosure for mystery driver

[timsch75]

I've got a couple of 5.5" full range Nissan drivers that have been given to me. I want to use them in my '88 supra, but the speakers are 4", so I can't use the mounts. I'll need to make some boxes to mount the drivers, but know nothing about their parameters. I was thinking along infinite baffle lines of making boxes with an open bottom that would be placed on the carpet, or an open back. I know that this is a far cry from good audio practice, but I don't need to put that much effort into them since my stock stereo won't make them sound that great anyway.

Any rough guess on what size box an average 5.5" speaker would use? I'm just trying to make the speakers functional.

thanks for the input.

tim s