David-aviator
Well Known Member
John Deakin from AVWeb has a great column that I've read and learned a lot from. I cut a pasted parts here, but go read the entire article for the full effect on the subject. I know this info is not about gallons per hours flow, but for those of us with a flow meter, it is good info.
Normal climb CHT in a well-baffled normally aspirated engine is around 330?F at full power and sea level, at any decent climb airspeed. CHT might be higher if you insist on low climb airspeeds. If you see higher CHTs on your engine monitor, your fuel flow is too low. A lot of these fuel flow indicators are not very accurate at all, and most are not even true fuel flow gauges at all. They're pressure gauges, marked in flow. We really like digital fuel flow systems that have been calibrated by actual tests for this reason. If your redline is 27.0 GPH, and you get only 26.5, have it set higher.
I don't want to be a curmudgeon and dispute a highly regarded published guru, but there are more factors to CHT than fuel flow and baffling - perhaps as great a factor as anything - outside air temperature. A CHT of 330 can not be in boiler plate and I don't think there is a need to be concerned if it is not.
I believe it is a generally accepted engineering premise that all things being equal, if you see 330 CHT flying in 50 degree weather, you will see 370 when flying in 90 degree weather. Yes, fuel flow is a factor but it is not the total answer.