quote:

ORIGINAL: Lee Willis

500 rwhp is in a no man''''s land for LS1 through 3 engines.  The stock block and bottom end can handle about 475 rwhp with fair durability you take something out of its lifetime but I''''ve seen engines go to as many as 160K miles with mods that dyno an honest 465-475 rwhp, so its not too much you give up.

I''''ve had several data points (one of them mine) that a stock short block will not last very long at 500 HP and over  I''''ve seen blown, NOS, and just highly modded/ LS V8 s through 3 engines producing between 510 and 540 dyno HP come apart.  These are engines I had personal experience with: one cracked block, two sets of rods that apparently went bad. 

Thus, 500 HP is a bit too much unless you rebuild the bottom end and if you do, might as well go for a lot more.

quote:

ORIGINAL: Lee Willis

700 HP flywheel (about 620 rear wheels) is very do-able but not with a stock block.  I''''''''d go with with an iron LS3 type block, basically out of a Silverado pickup, etc., I have one in my Camaro, and I''''''''d buy the entire short block built up nothing fancy, Eagle routating assembly (heavy but strong, and econonomical).  I''''''''d spend good money on heads at about 9.5 to 1 compression, although if you are going to force induction you really don''''''''t need great heads let the supercharger do the work. 
You could do turbos, but there, I have little experience. with Superchargers, you will need something larger than the size reocmmended for stock applications: for example with ProCharger they list a P model that adds about 125 rwhp to a stock C5 or C6.  It won''''''''t blow enough for an opened up 408. You need to move up to a D1 which will do you to about 750 rwhp.  Other options are a Kenny Bell or the biggest Magnusen (maybe, it would be marginal), or Vortex makes a model equivalent to the D1. 

OPh, and you will also need an oversized radiator, and if you are building up an early C5, replace the alternator bracket with one from the last year of C5 production (the early ones break under the tension of a SC''''r belt).
The transmission will not take the power, but there are upgrades you can buy.  Neither will the rear end without a girdle and harden half shafts.  You will still have problems with the Supras running 2 bar I had 700+ RWHP and they still gave me surprises.  But they difference is I never saw one that was really daily driveable.  do it right and your 700 Hp vette will drive to and from work just like stock.  Mine did.  

quote:

ORIGINAL: Lee Willis

EVentually, with about 800 HP flywheel, and slicks, good engine and chassis tuning, I did low tens best with mid tens consistently. 650 flywheel should do high tens or low elevens dpending on the tires, the chassis set up (it takes a lot of fine tuning to get that much power to the ground) and the track. 
   As to rear end, I stuck with the stock 3.42 rear end ratio, but had I kept the car would have gone upstream to a 3.15 or so.  With the stock ratio and drag radials, first gear was nothing but hopeless wheelspin anyway: I think the car would have pulled off the line sjust fine with a 3:15 and it would have given me a higher speed in gears going through the quarter mile.