CHTs on PPonk 182R

[Katamarino]

I have recently bought a 1981 C182R, with 80 hours SMOH on a PPonk conversion.

The CHTs are quite varied across the cylinders, and I'm unsure if this is normal. The engine had all new baffling done when installed. Cylinder 5 is the one that has the differently placed temperature probe.

This is the first aircraft I've had experience of with an engine monitor, so it's all very new to me.

In the climb:

In cruise:

Cylinder 3 is always the hottest for both CHT and EGT. Not sure if this is normal or perhaps there's a little induction leak we need to track down?

 

[Stewartb]

5 can use the Cessna 185 cylinder shroud that's used on 185s. 6 needs to have a partial block fabricated. 3 or 4 being the warmest is common. Induction leaks are usually found at the Y pipe and that impacts one side or the other, not usually #3, but you should cinch the rubbers every time the cowl's off just in case. If you live in a cool weather climate you need to insulate your balance tube.

 

[Katamarino]

Stewart, thanks. The aircraft does have that block one side, and the cooler the other.

Anyone else have any input on whether this spread of CHTs is normal, or I need to be worrying..?

 

[Clark1961]

What is “Welcome to temperature performance of a carbureted engine for 100, Alex”?

I really don’t know since the only stuff I’ve seen with a monitor has been fuel injected.

It never hurts to see if the clamps on the intake system are tight any time the cowl is off.

Check the temperature profile as the engine is leaned. Not really diagnostic for your concern here but it does tell you what the engine is doing for various fuel flows at constant rpm.

One trick to try to help even the mixture distribution is to give it a little carb heat when leaning. Mixed reports of success. May be old wives tail but can’t hurt to try.

A mechanical problem which resulted in hot cylinder had temps over 400 so you aren’t in that area. So if compressions are good and plugs clean then mixture distribution may be the cause. Might check time since mag inspection. Does it idle smooth when hot and cold?

 

[Stewartb]

When fuel condenses in the balance tube 5 and 6 will run fat. That's why we insulate them. Other than that? Make sure you have at least 150* of leaning authority on a standard day. That is, the difference between full rich and peak needs to be >150* in warmed-up level cruise. Your hot cylinder is in a happy place so you don't have the problems some guys do. Your temps look pretty good to me. Is your climb screen at full throttle? Fuel flow should be a little higher than that. And I never run mine below 15.5 gph but I usually rin 24/2400 or a little higher. My temps used to be uneven but leveled out when I increased the fuel flow.

 

[Katamarino]

When fuel condenses in the balance tube 5 and 6 will run fat. That's why we insulate them. Other than that? Make sure you have at least 150* of leaning authority on a standard day. That is, the difference between full rich and peak needs to be >150* in warmed-up level cruise. Your hot cylinder is in a happy place so you don't have the problems some guys do. Your temps look pretty good to me. Is your climb screen at full throttle? Fuel flow should be a little higher than that. And I never run mine below 15.5 gph but I usually rin 24/2400 or a little higher. My temps used to be uneven but leveled out when I increased the fuel flow.

That was full throttle in climb, but at about 9,000ft. About 19/2300 in the cruise. Thanks for the advice, will try as soon as I'm able!