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- Jan 21, 2021
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Hello all,
I have a debate ongoing at the moment regarding acceptable low CHTs in Arrows (IO360-C1C). Our Arrow as well as that of a neighboring friend are pretty low from my point of view. They average is in the high 200s (ours) or the low 300s (his). Below a screenshot of our averages during this flying season. At least the other Arrow has confirmed an accurate mag timing (20° BTDC, as specified for the type by the latest AD in 1976), ours I would like to get checked sometime soon. So two arguments: On on the one side, I have my co-owner, the owner of the other Arrow and our local mechanic who don't see a problem. They argue, the Arrow (or PA28, for that matter?) has a very well-designed cooling/baffles system and therefore by default has lower CHTs than other types. They also argue it's not a problem and make the point that other water-cooled (non-aviation) engines reach temps in the region of 200 F as well (I doubt the degree of comparability here though as other engine concepts will use other materials, possibly no lead etc. which changes a whole lot of parameters). On the other hand I have Mike Busch arguing that our CHTs are WAY too low and it's a safety of flight issue as it encourages sticky valves due to incomplete combustion and lead deposits (we've had a sticky valve incident during a ground inspection last year).
I'm really curious what are average CHTs that other owners are getting on their comparable types and engines. Is it true that our temps are standard or are they very low and something should be done about it?
For reference, most of our flights are in the 5000-6000 ft range either run at about 25/2500 or 25/2100 and usually leaned to 100° ROP using EDM700 Lean Find. Although I have experimented with other leaning strategies to bring up the temps, i.e. I've done some flights at peak EGT or just slightly ROP, but it didn't have any noticable effects on the CHTs.
I have a debate ongoing at the moment regarding acceptable low CHTs in Arrows (IO360-C1C). Our Arrow as well as that of a neighboring friend are pretty low from my point of view. They average is in the high 200s (ours) or the low 300s (his). Below a screenshot of our averages during this flying season. At least the other Arrow has confirmed an accurate mag timing (20° BTDC, as specified for the type by the latest AD in 1976), ours I would like to get checked sometime soon. So two arguments: On on the one side, I have my co-owner, the owner of the other Arrow and our local mechanic who don't see a problem. They argue, the Arrow (or PA28, for that matter?) has a very well-designed cooling/baffles system and therefore by default has lower CHTs than other types. They also argue it's not a problem and make the point that other water-cooled (non-aviation) engines reach temps in the region of 200 F as well (I doubt the degree of comparability here though as other engine concepts will use other materials, possibly no lead etc. which changes a whole lot of parameters). On the other hand I have Mike Busch arguing that our CHTs are WAY too low and it's a safety of flight issue as it encourages sticky valves due to incomplete combustion and lead deposits (we've had a sticky valve incident during a ground inspection last year).
I'm really curious what are average CHTs that other owners are getting on their comparable types and engines. Is it true that our temps are standard or are they very low and something should be done about it?
For reference, most of our flights are in the 5000-6000 ft range either run at about 25/2500 or 25/2100 and usually leaned to 100° ROP using EDM700 Lean Find. Although I have experimented with other leaning strategies to bring up the temps, i.e. I've done some flights at peak EGT or just slightly ROP, but it didn't have any noticable effects on the CHTs.
