Engine clearances

Building your own engines, most believe more clearance is needed to go faster and it does apply if only by heat of expansion takes place to make up the difference!  While oils get thinner with heat and flows faster more has to be pumped and retrieved! Warming up before hand is best if extra is used! If running cooler, no more than stock is needed! Piston skirt length and friction factors there are however the best place to start! A fine slick as glass cylinder may require less, unless running lean expands the piston! A minimal scuff to hold lube on the skirts are in place on most all pistons to carry it smoothly to the top! Coming back down is the two strokes of concern in keeping it cool to start with! A quick rounding of the bottom edge of the skirt keeps it from shaving off the lube to hold center better and have less friction by added clearance and by cooling the piston and holding said clearances! The only heat in the engine should come from the burn and not friction related! More clearance does not make it so, control does! If no high oil pressure is used spewing friction of the oil does not heat it up taking the whole engine with it! Heads take the brunt of the burn heat with its thinness through to the water jackets! Clearance there and heat factors applied to oil passing by can go to extremes! Keeping a minimal amount of oil up stairs and more down low cool is just part of its thickness to your set clearances! Less pumping and slinging causing it to drag its way back down away from the heat and adding friction by forced movement can add oil heat in the process! Polishing the surface of the block to speed it on its way back down has merit if starving because of clearances left open, but if cooler the oil can cool the engine with each little bump in encounters dragging more heat out of the engine! A painted block of the correct paint can create a barrier for heat to travel through or send it to towards the coolant as intended setting up a flow of energy from hot to cold of which is most natural! Stock seems to be just fine on a crank and only pistons deserve my attention by design and needed improvements! Metals and heat factors as well as lube sets the bar for friction to be over came! If you wish to add clearance and higher temps to close the gap to your engine to need oil more to compensate, pump it like compression and rob the horses that is your choice and I will keep my distance! I however am not against better quality parts if affordable or needed! Knowing the difference can adjust  your car clearance on the track!