Antonio wrote:
Then your engine layout must be closer to this
Yes that’s coming close! I can’t actually see it whether this Comanche already has the long Tiger Shark nose, but the baffling looks the same. Oil cooler is on the same place. In flight direction it’s on the left side of the firewall, the air intake is on the right side.
Antonio wrote:
180KTAS at altitude LOP
Yes it should actually.
I made some testing on my last 850nm flight to Spain and am very impressed about how important the baffling is. I found a quite big hole close to cylinder 6 in the baffling and closed it (prior to the flight of course). It should be closed with a piece of felt, and it is still there but not in the right position. Temperature of cylinder number 6 (my hottest one) went down from 390 to 310°F on identical power setting. I couldn’t believe it. Found some more leaks and am working on perfection here to get all cylinders to similar temperatures.
So maybe when all baffling work is done the temperature indications of the original probe and the JPI probes might come closer to one another.
As a sidenote I think I’m lucky that I have the JPI probes installed. If it wasn’t for them indicating the high temperatures I wouldn’t have reduced the power so far, and would have ended up with a roasted engine.
UdoR wrote:
analog CHT gauge shows never more than something like 220°F to maybe 250°F.
you probably have a piggback kind of adapter on whatever cylinder the factory cht is plugged to.
This can cause jpi to show lower cht (or higher depending on how it is connected).
what you can do is just boil some water. Dip the factory probe in it and jpi probe. See what they read on the gauge.
you can see that which probe is more accurrate.
@Peter hopefully you like seeing your engine in a simple application (unlike TB21) where it is able to provide full power at FL200!
A pity @UdoR has not yet found a useful way to use higher than 50%…but he is on the way to addressing it! I bet this aircraft can do better than 180KTAS at altitude LOP once properly set up.
Then your engine layout must be closer to this
But this one has the oil cooler on the bottom rh of the latter pic
Aha! 260 TC nice! Then all the info on baffling should be in the OEM documentation.
I’m glad you know how baffling works. You’d be surprised at the number of aircraft out there with reversed or missing baffle seals or inter-cylinder baffles.
Antonio wrote:
I guess similar to how yours should look like
No, it’s not even near similar. Thanks for sharing, but the air flow beneath the turbo cowling is really quite totally different. It is not only that the Tiger shark cowling of the “C Comanche” already has a different airflow to what looks like a B Comanche in the pictures, the Turbo needs a separated air flow for air intake and that goes right from the inlet over the cylinders. On the other side of the engine is another portion of airflow directed on the oil cooler which sits on the firewall. So yes, I know what baffles and seals are and how they should perform. We won’t solve that here. I have to inspect my baffles and seals and do whatever might be necessary.
Antonio wrote:
I used to have spring-loaded JPI probes on the cylinder of my former IO360 and they were very accurate. Are those the same type that your O-540 uses?
Yes those look quite similar to what I have installed.
I might add that according to my information here Lycoming states that the metallurgy of my engine differs from other engines, so that it may be run hotter by at least 35°F.
