Old Fart on a 65 Texaco repeat Texaco (note RPM which is 45 to 4800) we run 15 x8, x7 or x6, This is a fuel economy event looking for long engine runs. For Duration (vertical drag racing), timed engine run 32 seconds we use sparingly 13x6 Bolly or APC or even 12x7 or 8 depending for a 10K Rpm + range. In all cases we are looking for height at the end of the run so we can stay up longer in the glide. A "max" in the rounds for Texaco is 10 minutes and Duration it is 7 minutes. In the fly off it is all up last down essentially, actually the longest flight. That is the basics
I get my castor fix when ever I run my ED's or Burford diesel engines. Mixed with ether it is socially acceptable.