Intercylinder baffle to Vans baffle distance?

[LAL]

Having searched the lists I have been unable to come up with a suggested spacing between the lower intercylinder baffle and the Van's baffle as it curls under the cylinders and heads. Flying an IO360 A1A angle valve from a Mooney (and thus probably the intercylinder baffle is optimized for the balance of their baffling?). Current distance is about 2" at cylinder and 3" at head. In the fog of my memory, I think ideal is 1" and 2.25" respectively.
Long and mostly unpleasant cooling story here, but am gathering more data before I can summarize it in a post.
Thanks much,
Len

 

[az_gila]

Starting point...

A good starting point is to make the gap symmetrical around the temperature probe well....

gil in Tucson

 

[LAL]

not following this...

Gil,
Not sure I am following you on temp probes. After you install the safety wire or spring system to draw together the Vans baffle underneath the heads and cylinders, what is the measured (suggested or empirically ideal) distance between the Vans (or similar) baffle and the intercylinder baffle?
thanks,
Len

 

[db1yg]

Len,

Your memory is consistent with Sam James recommendations for a starting point. I used 2.25" and 1" as the starting point on my ECi 0360 RV9a and then fine tuned the openings based on the individual chts.

Good Luck and Cheers,

db

 

[az_gila]

Another try...

Gil,
Not sure I am following you on temp probes. After you install the safety wire or spring system to draw together the Vans baffle underneath the heads and cylinders, what is the measured (suggested or empirically ideal) distance between the Vans (or similar) baffle and the intercylinder baffle?
thanks,
Len

Len... the temperature probe well and the lower spark plug hole define the center-line of the cylinder. This line is along the cylinder (90 degrees to the crank) and at it's lowest edge...

Start off with the baffle wraps that you fabricate being an equal distance from this center-line as the Lycoming inter-cylinder baffle is in the other direction.... this will give two dimensions, one for the upper cylinder fins, and one for the fins around the cylinder barrel.

Hope this makes sense....

gil in Tucson

 

[rv969wf]

2 1/4" x 1"

Having searched the lists I have been unable to come up with a suggested spacing between the lower intercylinder baffle and the Van's baffle as it curls under the cylinders and heads. Flying an IO360 A1A angle valve from a Mooney (and thus probably the intercylinder baffle is optimized for the balance of their baffling?). Current distance is about 2" at cylinder and 3" at head. In the fog of my memory, I think ideal is 1" and 2.25" respectively.
Long and mostly unpleasant cooling story here, but am gathering more data before I can summarize it in a post.
Thanks much,
Len

Hi Len and others,
I have tested and tested many configurations about cooling issues over several years on my -6 trying this and that with much studying, trial and error as to what worked and what didn't. From what I've found and take this at your own risk, but a 1" gap on the cylinders x 2.250" gap at the cylinder fins is ideal to capture the air completely around the cylinders head fins and barrels. If this gap is more than that, your going to have uneven temps around the barrels and heads which will cause to the cylinders to be out of round with hot spots. Lycoming and others use test probes around the barrels and heads to find hot spots, what I did was use heat crayons of various temps to check my temps around the barrels and at different places around the heads. There is no way to get perfect temps all the way around a round cylinder or the head. Where the CHT probe is located, is only picking up temp at that one point. If the baffle gaps are opened up or closed down, yes you will see a difference in the probe temp, but no one has any idea what the temps are around that cylinder or head in other areas. What I found best to balance cylinder temps is on the top side, not the baffle gap on the bottom, don't alter that, keep it at the 1" x 2 1/4" and don't monkey with it. You can make 30-40F degree temp changes on the top side, meaning the baffle gaps that wrap around the front of #2 cylinder head and the rear of #3 cylinder head. The front two cylinders I've found out are most ideal with them blocked off at the front with a gap behind them. Guess what I'm trying to say is if you look into the cowl inlets, the cylinder head fins cannot be seen except about the top 1/4" of them. I have 3-D shaped ramps or whatever you want to call them located in front of #1 &#2 with space behind them to allow air to enter, but not a direct blast of incoming air because those front cylinders fins do like a direct blast of incoming air. Air management is the key with no leaks around the sides of the baffles where they wrap around the fins. BTW, I just returned from a Flying trip today with 90F air and my hottest cylinder came up to 320F and my coldest one at 310F. This is with 2 3/4" round cowl inlets cooling a 200HP high compression Lyco. If you need some help feel free to private message me. Good luck and take what I've written at your own risk.

 

[LAL]

intercylinder baffles

Gil.. got it. Thanks. Makes sense now. Dave.. thanks for clarification on spaces.
Alan.. again, I appreciate your suggestions and will adjust combining appropriated dimensions and Gil's suggestion about where the gap is centered.
Len