To that, add "the more accurate the machining, the closer the temperature control, the tighter you can run them."The better the parts are, the tighter you can run them.
Today's OEM economy car engines have more accurate machining, better metallurgy and better temperature control than the best blueprinted race engines from back in the day. Check out the radiators in today's cars. They have less water in the block and radiator than the heater and defroster cores of an older car. (Those of us old enough can remember when they were two separate systems.)
As I mentioned earlier in the thread, .0005"-.0025" was an acceptable range for main bearing clearances back in the day. With better, lighter oils, better parts, more accurate machining available to us, temperature control is the one area which is still not done to best science on most builds today.
thnx, jack vines