182T IO-550 Conversion CHT's

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fishyfishy

Filing Flight Plan
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Recently (11 months or so) I had Texas Skyways install the Continental IO-550N engine in my 182T. They did a great job and the performance is great. The only issue I've had are the CHT's on the 2 front cylinders #5 and #6. In the beginning #6 was the warmest and was about 50-60 degrees warmer than the 2 rear cylinders. They were able to trim the metal baffling on the front of the cylinder and the temperature came inline with the others. The #5 cylinder has been tougher to reduce the temps like #6 because the alternator is located in the front of it. They have removed air leaks by improving the baffling and the temps have come down some but is still about 40 degrees warmer than the rear cylinder on that side. I never have been able to really lean it to rich of peak because #5 temp always starts climbing to the point where I think it would overtemp so I always back off and add fuel. At 10k' I can lean it to about 15 GPH and close the cowl flaps to about 50%. I'm ok with the fuel flow and I could probably get another knot or 2 if I was able to close the cowl flaps, but even so #5 is still going to be 50 degrees warmer and will be around 370/380 degrees while the #1 cylinder in the back will run about 320/330 degrees. The cylinders on the port/left side are all within 10 degrees of each other.

I'm no expert but it seems to me the airflow across #1 needs to be decreased somehow which would probably increase airflow across #5. I could use some ideas on how to do that. Other suggestions appreciated too.
 
Those are great temps. Go fly it and stop worrying about it!
 
For giggles can you have them swap injectors and probes to see if you issue migrates to different cylinders?
 
You might also try - instead of trying to go LOP slowly, do the BMP (Big Mixture Pull) and find the best setting from the lean side.

While there are obviously lots of variables at work, your temps and the total spread seem fine but my #5 was actually one of the cooler cylinders, which I believe is somewhat normal for the front 2 to be the cooler ones. Anything on the downstream side of that cylinder blocking airflow?
 
Blatham489 said:
You might also try - instead of trying to go LOP slowly, do the BMP (Big Mixture Pull) and find the best setting from the lean side.
Click to expand...

^This. The more LOP you run, the cooler your CHTs will be. If you can't run LOP, due to roughness (uneven flow to cylinders), you'll have to stay ROP and burn a lot more 100LL. You can also use some aluminum tape to cover some of the cooler cylinders but also continue to seal holes in the baffles to improve things.
 
Ray Eaker said:
^This. The more LOP you run, the cooler your CHTs will be. If you can't run LOP, due to roughness (uneven flow to cylinders), you'll have to stay ROP and burn a lot more 100LL. You can also use some aluminum tape to cover some of the cooler cylinders but also continue to seal holes in the baffles to improve things.
Click to expand...
I like the tape idea to see if I can increase the pressure toward the front cylinders.
 
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