Assuming a bone stock 2009 GT, automatic. Add a supercharger. How long would that hold up as a bracket car...say making 200, 1/8th mile passes per year? Can that OEM motor handle 475 HP RELIABLY?

 

Your starting to push the limits above 450hp. It all depends on the quality of your rod castings (weakest link in a stock 3v). Some have been putting down over 500hp for several years and some make nice windows in the block at 450hp and some as low as 400hp. It's pretty much luck of the draw but a good conservative tune will definitely help it live longer but that's not really ideal for a drag car. Also keeping it wound up at high rpms a lot stresses it more. If you have another block or don't mind buying one to do a built motor with id say run it till it blows and you can just build a motor as you go. But if you want to save the cash for the block I'd just build what you have now.

 

I'd say it has to do with how hard the launches are, how high the RPMs go, and how good the tune is.
IF you're spinning the tires, shifting below 6,000 RPMS, and have plenty of fuel and timing it should last as long as any block... If you dead hooking and pulling wheelies, shifting at 7,000, and have the timing as aggressive as possible... then it's a ticking time bomb.

 

I wouldn't worry too much about the engine. Having it tuned for the 450 rwhp range and an excellent transmission tune will be the best thing you can do for it.

I would be more concerned about the longevity of the tranny with that much power and that many passes.