Quote:
Originally Posted by lr172
I had always assumed that the air flow past the engine was based on a pressure difference and not necessarily air flow. Given that the chamber is common, I would expect any leak would equally affect the cylinders. I am hoping an expert can chime in here, as I am struggling with a warmer #4 and would really like to understand if my assumptions were correct or incorrect. I suppose the effectiveness of the dams on #1 and #2 at least partially disproves my thinking.
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This partially makes sense as you mention. I would agree about the common chamber but when people can improve cooling on #3 by adding a spacer or air dam behind #3 also proves that improving airflow in one particular area of the chamber can help. Likewise perhaps improving airflow too much at another area, in the wrong place can also hurt CHT’s.
For example, let’s say instead of adding airflow behind #3 you add airflow behind #4, and so much airflow that instead of going through the cooling fins of #4 its going out through the oil cooler, or a leak in the baffle?? Does path of least resistant rob cooling air from a nearby cylinder?
If so, and your oil temps are low, you can try and close off the backside of the oil filter. Less air through the oil filter should yield more air through the cylinders.
Baffles on the front of #1 and #2 cylinders seem to do two things, 1) raise the temp on the front cylinders 2) deflect more air to the rear cylinders. You should be able to toy with the front baffles enough to level the temps between 1 and 3 equally and 2 and 4 equally. But, if you have FI, there is no reason you shouldn’t be able to level the temps between all 4 cylinders by flow matching the injector orifaces. Is it possible #2 and #4 are currently blocked?
Lastly, a good set of mcfarlane cowl saver baffle material is far superior to the standard engine baffle rubber and if done right will provide a much better seal to the top cowl.
http://www.vansairforce.com/communit...hlight=Baffled
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