K-4 climb rates.
 

4820 ft per min is oft listed, but is that the 1st ones that rolled off the assembley lines? sept-Oct 44? or is that for spring 45 with uprated engines?

& the 1.98 rated engines that were last ones to roll off, ( 140 examples some say). What was the speed of these? were "these" the 452 mph ones? or were they perhaps even faster? or not.