Warm Wx Numbers

[kitfox812]

I have a Kitfox ss-7 with over 900 hrs on it. I am getting a little nervous
about the temps.

Last evening the OAT was 83 at 3500ft and everything got a little warm.

My CHT's were 230 and 249.
My Coolant (evans) was 230
My EGT's were fine, 1380 or so

These number are below specs but they seem high.

How does this compare with some of the numbers other people are getting
on a 912uls?

[Dorsal]

I'm having a similar issue, just came back from a fly-in, 75 deg OAT, 5000 rpm with oil at 230, CHTs nearing 300. If I pushed it harder (or on climb out) things would have gone into the red.

[leptronjohn]

do you guys have oil coolers on these guys, where is the radiator mounted?
john

[Dorsal]

Yes and in front of the coolant radiator. In my case I am not sure the numbers are real so that will be the first thing I check. I did have a problem with erratic oil temp reading but that is not the case here.

[desertfox1]

Testing a new prop before Oshkosh trip today. Temps were
240 oil and 245 CHT at 5200. Took a little pitch out and flew
for an hour at 4000', 205 oil and 215 CHT. This is about avg
for this plane when it is this hot. Its Phoenix in July!

Phil

[kitfox812]

Yes, for me to and I forgot to say that my oil temp was in the 230 range also.

I use the GR Digital EIS and I think it is pretty accurate.

I flew to Arlington last year at 6500 ft and I don't remember the temps being this high.

[Dorsal]

I am planning on closing the gap under the radiator at the back of the NACA scoop. Have others done this and did it make a difference?

[War Eagle]

I fly with the 914 so we aren't comparing apples to apples, but I made sure the fit of the NACA duct scoop for the radiator cooling was a very close fit (but not rubbing). I also sealed the gap under the radiator before I flew the plane in the beginning so I can't really compare a before and after. I knew the 914 was going to be a furnace so I started off wanting to close off every gap where air could bypass the radiator.

I run the Evans product as well and I see temps in the 240-245 if I am getting after it on a warm day. But Evans is good for something like 275 or so. I wouldn't want to run my temps up there but at least I have margin in the coolant. Coolant temps of 245 haven't been a concern to me at all.

I have the oil cooler mounted behind the cowling where the lower air inlet enters. I run a semi synthetic oil that allows for temps up to around 245-250 degrees but I can get there really quick on high power settings and warm ambient temps. I have to watch this temp really closely or I could sail right past it. Even though the 914 uses a bigger oil cooler than the 912s, I am concerned about the oil temps and am looking for ways to build in more margin on it.

My egt's have not been as issue and cht's are basically coolant temps.

[HighWing]

I fly a Model IV, so take this for what it's worth - But. I helped a guy build a Lancair IV and monitored the forums during the two and a half years that project took. The oft suggested solution to high operating temps there was to reduce the size of the air inlets on the cowl. What the guys claimed is that the ratio of inlet area to outlet area should be about 1 to 1.5. The air should enter the cowl then slow down a bit as it progresses around the engine then exit out the larger lower opening. It is a low pressure system and the air has no problem entering the cowl.

Then I helped a friend finish a Series V with the Series 7 FWF. When we measured the inlet to outlet ratio, it is almost exactly the opposite of what is recommended. In other words, more air can enter than can escape so in the theory of the Lancair guys, some of the air sees the high internal pressures and simply bypasses the inlet. We added an adjustable flap over the NACA duct on the V to close it off a bit to see if the theory holds with the Kitfox design. Unfortunately he was transferred by his work and is still not flying so no report there.

Then there is the relative inefficiency of the Evans Coolant - it helps in an over temp situation by tolerating the high temps, but then hurts a bit by not being an efficient heat transfer agent.

In actuality it is very likely an air flow issue as the problems with the earlier models with the much smaller external radiator, is trying to get up to operating temps - lots of duct tape.

Just suggesting some food for thought.
Lowell

[kmach]

Hi,
from what I have learned , if you use evans waterless coolant your temps will be higher. about 25degrees .

Evans is not as efficient as 50/50 water/antifreeze for cooling when flying. Evans does have a higher boiling point so it helps prevent boil over on idle and taxi if the engine is running hot in those situations.

last summer on hot days 85 F my cht's would be 238-245F area with evans, I switched to 50/50 mix coolant when I changed my coolant system hoses now at 85F my chts are running 200- 225F area.

Hope this might help.

[Dorsal]

Definitely lower numbers than I am getting and for me it seems to be a recent change. I boiled my CHT sender last night (handy Jetboil camping gear) and it read 212 on the mark. Changed the oil, filled the coolant reservoir (was still half full) and flew some night quals, all was in the green. Will take it out again tonight and push some extended climbs to see what I get.