flyboy1963

flyboy1963

Well Known Member
I get the feeling I need more instrumentation....is one CHT gauge useful?
If so, it would seem that you'd want it on the one that typically runs hot....so is there a trend; on an 0-320, is one usually hottest?
I have my single EGT on #4, does the CHT have to be on that one to show the relationship when leaning etc?
...appreciate any advice.
 
Since you are carbed there's no way to know without full instrumentation. The fuel distribution can get pretty screwy depending on where the throttle is. For me, full throttle makes 1-2 hot. Back off a bit and 3-4 will get the hottest. Then when I lean things change again. This is where IO's, assuming the cylinders get flow matched, have a big advantage.
 
I think your first observation was right...you need instrumentation on all cylinders, especially if this is a new engine. I think the single channel instruments were probably good enough for certified planes where they were all the same and they knew what the cooling situation was. Are the new certified planes shipping with single channel or all cylinder instrumentation?

With ours, even the same engine and same air frame model have big cooling variations from build to build. In mine, not only does throttle and mixture change which is hottest, attitude and airspeed change it as well. You have to pick the condition that you are aiming to optimize. Without instrumentation, you're just guessing.
 
IMHO, you need all cylinders instrumented even if it is only a single channel instrument with a switch to switch between cylinders.

My O-320 RV-6 has been flying over 17-years and 1,954 hours.

At one point in time, I had Superior Investment cast cylinders. #2 was coldest cylinder all the time and hottest would switch between 3 and 4 depending on altitude and power settings.

Switched to ECI Titan through hardened steel cylinders. In climb, #2 is now my hottest cylinder with typically 3 or 4 when in cruise.

My experience with my airplane has different cylinders hottest at different operating parameters.
 
I always download the flight data logs from the Dynon Skyview and have a look at how temps and such are doing. The hottest cylinder will move around the engine depending on whether I am climbing or straight and level, or with or without the oil cooler shutter closed. All of the cylinders stay pretty close to one another - within 20 to 25 degrees max. Having all cylinders instrumented makes it very easy to diagnose any issues. I have over time cut down some of the air dams in front of the forward cylinders and surprisingly, they haven't had a huge affect in temps, but more in the balance of temps from front to rear.
 
good news, bad news...

Ok, great responses as always guys....I think my engine has about 270 hrs. might have one new cylinder ( 100 less hours)

sounds like if I only am worried about cooking something in a climb on a hot day, one might do......

but to 'manage' things, obviously reading all the conditions is needed.

for now, I'm in ostrich mode, happily driving along, oblivious.....
 
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