Wav to MP3 ????

Hi all,
Im a little confused :confused
I have a Wav file that I recorded nearly 7 hours of music onto,trying to see how much music I can fit,via MP3 on a cd disc,as i just found out my car stereo does MP3:-D
So I have a WaV file that is over 4 GB,I have loads of space still on my hard drive...anyway,I converted that file,via YOutube converter into a MP3,then I land up with only not even 9mb of music,when I add it for burning on infrarecorder it only comes up as 6 minutes in length:cry
How is that possible and what am I doing wrong,I have used this method to burn many cd's before.a;though not as large.
Can someone suggest another maybe better converter,it seems I have had this new burning problem since I agreed to the latest version of youtube converter?maybe.

 

However when I play this small file of 6 minutes(that reads 6 minutes) it plays the full 6 + hours?

 

When I play the WAV,the size just over 4gb it plays fine,nut when I convert it ti MP3 it comes out at only 6 minutes.
Disregard that last post as I could not edit

 

Audacity should do the trick with little hassle, http://majorgeeks.com/Audacity_d4427.html
dbpoweramp is a wonderful audio converter, but not open source.

 

Audiocity does,if one has the paid version.I dont
I just cannot understand how that WAV file could change in size so much,from 7 hours then in MP3 form to 7 minutes?