Nice flight

The weather finally gave us enough of a break to allow for some flying today. So, I took advantage of Mother Nature and went for a spin. I have had several requests for updates but there has been nothing to report. Until today.

 I took some pictures of the panel so folks can see what is going on with the plane and engine to reinforce what I have been saying about my testing. Remember, when you look at the photos I have the sensors under the head stud by the exhaust port. I'll keep it short and let the pictures do the talking.  I apologize for the fuzz, it was pretty bumpy, enough so I couldn't get a good one in the climb.





My scratch built creation waiting to go.





 

The cht was 310 in the climb, about 45 degrees ambient on takeoff.

The switches are set to show the maximum temp, or hottest cylinder on both instruments. In this case number two is 275 and the egt is 1338. Just about at the limit I'll allow.



Those of you who know what a Ch701 is probably realize it is a high drag airframe. Mine has all the high drag stuff just like the factory plans (slats)  except I installed strut fairings. This picture shows that the vw pulls it through the air pretty well. You have to watch it in rough air and not throw it around.

Here is a good shot of my cruise power setting, I have it 1" lower than usual because of the rough air. It would normally be 5.5 to 6" and 3900 to 3925 rpm. It is worth noting that wide open throttle is 3", before I advanced the camshaft 4 degrees W.O.T. would result in a indication of atmospheric pressure, or 0 inches.  The fuel flow has settled down to 7.3 gph which means I don't go far, about 1.5 hours. That's about as long as I can sit still anyway. The gps is showing ground speed in knots. 

8 minutes after the shot above the engine has settled down and all the cylinders have stabilized at this point.  I run a ellison throttle body injector which I think is a fine piece but I have a slight imbalance with my induction system that I need to work on. I think it would improve my fuel efficiency slightly if I could get the right bank a little leaner.  



Number 1 numbers. As you can see, by comparing the pictures the cht is pretty even, I have to work on the egt. Unfortunately I didn't get a shot of number four ( the right front) , it runs cooler by about 30 degrees

I go back and reread these postings when nothing is going on and see things I want to add, today is one of those days. Relocating the sensor to the center head stud from where I have it ( under the head stud by the exhaust port) would result in a reading about 20 degrees cooler than those in the pictures. In the earlier posts I address this, but I still have folks asking why I run the heads so "cool".  To me, they are not cool. I am sure there are places in that head that are much hotter than what the sensor is showing. If there were a way to get the sesors mounted down under the head under the sparkplugs I'd do that just to see what is going on down there. I also feel that the sensors are getting a little cooling effect from being on top in the air stream. Look at the pictures in some of the earlier posts to see what  mean.
  I have folks asking about the summer temps, they generally run a little hotter but not much more. In hot weather the engine makes less power until you get up to altitude so the heat rejection is lower. I have flown with the temps in the middle 80's and the CHT will run about 320 in the initial climb. I usually climb at 65 to 70 when it's hot getting about 500 fpm and the cooling holds it own.
  If anyone has any questions let me know. I think the next posts will be how I did my own dual plug heads, anyone interested?    

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