HomeBuilt101
Well-Known Member
Does anyone have any pictures of the lower Engine Cooling Baffles installed on their engine they can share?
I am going to fabricate some lower baffles for my Lycoming IO-540 so if anyone has any pictures of the lower part of the engine looking upward I would be most happy to copy your homework.
It would be interesting to do a study of the various designs of the engine cooling baffles...especially the lower baffles and compare the pictures of the baffles on airplanes with good cooling verses the airplanes with poor cooling and hopefully we as a cyber team can come up with some good practices.
Yes…step one is to eliminate all leaks in the baffles on top of the engine so that no cooling air is wasted…but what else is there???
What is the best practice for the engine baffle design?
How close should the baffles be to the cylinder head fins?
Should there be some kind of deflector installed on top of the engine to diffuse the airflow from hitting the top of the engine with blunt force?
Should the gap between the fins and the baffle be constant all of the way around the cylinder or should the gap be slightly greater at the top half of the cylinder and then get closer to the cylinder fins so as to not cool the fins as efficiently at the top and then as the air warms up as it makes it way around to the bottom of the cylinders it gets ducted more closely so that the cooling effect is more efficient?
Are aluminum baffles better than fiberglass or silicone wrap (I would think that anything that actually touches the cooling fins is creating a hot spot on the head at that precise location and anything other than aluminum would be worse than aluminum)?
Are airplanes with an oil cooler that gets its air from the upper chamber of the engine baffles system running more hotter (or just the side of the engine that has the “leak” for the oil cooler airflow) than the airplanes that do not have an oil cooler system that robs cooling airflow?
How wide should the exit slot at the very bottom of the cylinders be?
OK…I’ll start. Here are some photos of a cooling system that is not good.
Note that the outboard cylinders do not have lower baffles that wrap around the cylinders…in this example, it appears that the cooling airflow gets directed down the side of the outboard cylinder just about half way and then the baffle just stops. The top of all of the cylinders are getting brunt force airflow, the sides of the cylinders are getting airflow that is squeezed between the fins of the cylinders that are side by side until the air gets to the bottom and then there is a baffle “comb” that blocks the airflow from punching strait downward and directs the air along the lower half of the cylinders and then the outboard cylinders are also getting some squeezed airflow (although the gap is kinda large)…however…the entire lower half of the outboard cylinders are not getting any strategically directed airflow at all.
This leads me to believe that the top of the engine is freezing…the sides are nice and warm however the bottoms are frying…This would undoubtedly make the CHT sensor confused because it is sensing the temperature at the internal lower part of the cylinder and because of the uneven cooling (heating) the round cylinder must be getting egg shaped. This would prevent the piston rings from floating around in the bore.
There has got to be some science to this process as opposed to just experimenting…
I am going to fabricate some lower baffles for my Lycoming IO-540 so if anyone has any pictures of the lower part of the engine looking upward I would be most happy to copy your homework.
It would be interesting to do a study of the various designs of the engine cooling baffles...especially the lower baffles and compare the pictures of the baffles on airplanes with good cooling verses the airplanes with poor cooling and hopefully we as a cyber team can come up with some good practices.
Yes…step one is to eliminate all leaks in the baffles on top of the engine so that no cooling air is wasted…but what else is there???
What is the best practice for the engine baffle design?
How close should the baffles be to the cylinder head fins?
Should there be some kind of deflector installed on top of the engine to diffuse the airflow from hitting the top of the engine with blunt force?
Should the gap between the fins and the baffle be constant all of the way around the cylinder or should the gap be slightly greater at the top half of the cylinder and then get closer to the cylinder fins so as to not cool the fins as efficiently at the top and then as the air warms up as it makes it way around to the bottom of the cylinders it gets ducted more closely so that the cooling effect is more efficient?
Are aluminum baffles better than fiberglass or silicone wrap (I would think that anything that actually touches the cooling fins is creating a hot spot on the head at that precise location and anything other than aluminum would be worse than aluminum)?
Are airplanes with an oil cooler that gets its air from the upper chamber of the engine baffles system running more hotter (or just the side of the engine that has the “leak” for the oil cooler airflow) than the airplanes that do not have an oil cooler system that robs cooling airflow?
How wide should the exit slot at the very bottom of the cylinders be?
OK…I’ll start. Here are some photos of a cooling system that is not good.
Note that the outboard cylinders do not have lower baffles that wrap around the cylinders…in this example, it appears that the cooling airflow gets directed down the side of the outboard cylinder just about half way and then the baffle just stops. The top of all of the cylinders are getting brunt force airflow, the sides of the cylinders are getting airflow that is squeezed between the fins of the cylinders that are side by side until the air gets to the bottom and then there is a baffle “comb” that blocks the airflow from punching strait downward and directs the air along the lower half of the cylinders and then the outboard cylinders are also getting some squeezed airflow (although the gap is kinda large)…however…the entire lower half of the outboard cylinders are not getting any strategically directed airflow at all.
This leads me to believe that the top of the engine is freezing…the sides are nice and warm however the bottoms are frying…This would undoubtedly make the CHT sensor confused because it is sensing the temperature at the internal lower part of the cylinder and because of the uneven cooling (heating) the round cylinder must be getting egg shaped. This would prevent the piston rings from floating around in the bore.
There has got to be some science to this process as opposed to just experimenting…
