No, even with an aluminum piston, 0.002" clearance will be enough. Sometimes people deliberately make the piston about 0.001" oversize, then "wring it" into the cylinder using diamond lapping paste. If you do that, you can get away with no piston rings at all. That is effectively zero clearance, and is often used on two cycle engines where a piston ring would get caught and break on the cylinder ports. You wouldn't do that with an aluminum piston, because it expands more quickly than cast iron and could seize in the bore.