Per the instruction with my Sirio engine. Idle for 15 minutes and then you are fine to race tune it. Everyone has there own way to run in an engine. I think the words "break in" are really for the old type ringed engines. You should "run in" your new ABC/ACC engine at real world temp. IE 200 degrees. I use to spend all day breaking in my engines and they would only be fast for 2-3 gallons. All of my engines in the last year I have used the fast is fast method and they last me all year. I have done a collary .12, Sirio .12, Nova .21 SBK, 3 O.S. .21 o1, 2 Nova .21 CLB's & 2 nova .12 MT12. They are all still running and they are all very fast.