[quote=JoeWagon]2 more quick questions though:
is that stress=rpm^2 an actual equation or is it an estimate and statement of how important rpm's are to stress factor?[quote]
You cant get the actual amount of stress, but you can get roughly how much it will increase, with rpm. Stress will go up with the square of the rpm increase. I read that a 10% increase in rpm equals 25% increase in stress. I'm no mathematics expert, or I would attempt to explain how to figure out what a particular rpm increase would do to stress. Perhaps some one else can put the above phrase into an equation so it makes some sense. IF not I will try to figure it all out and then explain.
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also, was it you that had the engine that COULD go 10.5k but set it lower for practical reasons (keep in power band)?
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The rpm that a motor is "safe" to go to is determined largely by the weight and strength of the crank, rods, and pistons/pins/rings, and the rod ratio. A long stroke motor has a bad rod ratio and there is a lot of sideways intertia relative to the length of the stroke. They generally dont rev as high safely. But there are things that can be done about that. Magnus motorsports takes thier 2.4 liters to 8500 rpm. To rev really high, do the opposite. Destroke the motor
10k rpm in a 4g64 block with 4g63 crank (2.1 liter) should be a pice of cake. But you'll need intake exhuast, cams, turbo, etc that will work at the high airflow rates that wil go with rpm that high. VE will be tough to keep up. But based on the fact that making torque at higher rpm makes more power, it would be worth it for an all out race car. The trick with dSMs will be to get a tranny that will shift that high.