My supercharged 1996 Buick Riviera had a pulley freeze up which destroyed the supercharger belt.  The belt only drives the supercharger.  I realize that acceleration will be slower but what other overall performance changes will I experience if I do not replace the pulley and belt?  Will the MPG stay the same or get better?  Can I use regular gas instead of super?  Is there any harm to the engine or to the other electronics that are used for the supercharger?  Any thoughts on this would be appreciated.

I am not a mechanic but I too have a 96 buick SC  and my supercharger was bypassed by my ex (big retard!)  and I went without it for 9 months until I ran into a real mechanic who told me to get it hooked back up.  He stated that the engine is designed to run in conjunction with the supercharger engaged and without it your overall performance is compromised.  If you go too long without it running, the supercharger itself will freeze up and will have to be repaired or replaced and I have done the research on it and most mechanics don't even want to touch it without a hefty deposit.  My advice to you is: If your supercharger is okay, replace your damaged pulley and the two others with new ones. (the new pulleys will not be plastic and will be more durable and you won't have to worry about replacing them later) Buy a new belt and get it hooked back up.  I was also informed that without your supercharger, you are restricting your air flow to your engine and causing poor gas mileage.  I took my friends advice and replaced all pulleys, put a new belt on and I am completely satisfied with the improvement in preformance of my engine.  Besides, I love my car and who want's to drive one of these sweet rides without that extra power for when you need to do some quick passing on the highway?  LOL  I hope this helps.

PS. My overall parts cost was about 100.00 for all three pulleys and the belt and I paid a friend to put them in.  I got off cheap with the labor because I didn't take it to a dealer ship.  My advice is to find a local mechanic who had done this repair before so that he knows about the brackets that have to be removed.  This took him about 3 hours for a first timer.  But, he also accidentally broke a bolt off when he was pulling one of the tensioners off and that added some extra time of boring it out.  Good luck with your car.

Have it replaced or run into more problems. The PCM (the brain of your car) is designed to control the motor with it working. The pcm is making changes to your engine that it should not be doing because it doesn't know that the SC is not working.