Yes, I am talking about fuel injected engines only -- I thought the OP (well, necroposting OP) was too. He's flying a Mooney with a brand new engine that he's like to keep around for awhile, IIRC. Okay, that makes sense, and should be safely ROP at least in my limited experience (never taken off at high enough DA to need the technique) -- but it's not what I've heard some folks say. Full throttle on the runway, lean to maximum power, and go. I should check my POH to see what they say, but I believe what you say is correct, lean to peak RPM at runup RPM. I'm not sure if they say to enrichen from there. What do you mean by "it won't matter for detonation"? The red box is still there, albeit pretty small, at 75% power which is very possible in my IO-360 at 6000. I would really hesitate to set it to max power in a full power runup before takeoff unless the DA was at least 8000, maybe even 9000. 23 squared at 8000 is 65% power per the POH. I don't doubt it. Luckily around here, by the time I'm at 6000 MSL, it's cool enough that I've never seen CHTs above the low 300s no matter how hot it is near the surface. But I'm still wary of the red box even up there.