Not a new topic, but what is the current thinking on the power (and/or RPM) limits for a Teksid aluminum block, and for a cast crankshaft? My 2V set-up includes these two components along with a big bore (3.700") kit and forged rods and pistons. I'm planning to upgrade cylinder heads and positive-displacement supercharger to make more power. The current assembly has done fine at 470 crank HP, but I want to move up to about 650. Rev limiter is set at 6500 RPM, and that will not change. This is primarily a street car, but it does go to the drag strip occasionally. Am I asking for trouble?