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Rotorians,
Now that the airplane is painted, weighed, prop
ballenced and etc. I'm into tuning and getting comfortable with the
engine. Yesterday I noticed that as I ran the engine up, #1 rotor EGT
trailed #2 by 20 to 30 degrees and then at about 20 inches of manifold, #1
started climbing rapidly! At max static throttle 5828 rpm (prop
speed of 2045) or so, #1 runs to 1640 degrees while #2 maxes at 1480
degrees. I played with the mixture etc. No difference. I have
checked the plugs and swaped them. No difference. Stock RX-7
plugs. Pulled one and then the other secondary inj. connector.
It starts and runs and then drops off as RPM gets high. Same on both #1
and 2. Swapped injectors. No difference. Tryed using Mode 4,
both to increase mixture and then to decrease. No difference. Reset
Mode 4 back to default. Swapped EGT probes. High temps showed up on
#2 on EM-2. Swapped back. Checked the archives. Nothing.
The EGT probes are installed through holes in the exhaust 5 inches from the
engine outlet. So I am at a loss. Any thoughts on what might
be causing this? Engine basically running smooth and strong. Months
ago, I remember getting 6150 RPM, but couldn't get it to run long enough to
check out EGTs. Cooling problems. A couple of other things that may
or may not have anything to do with this. Manifold display on EM-2
sometimes jumps around some. I have tried porting to the front of the
intake and to the rear. Now I have it teed to both. Auto tune tries
to work, but does not. (O2 sensor installed at end of tangenial) I
ran it almost 2.5 hours total yesterday. 11.7 hours total. since last
December. Quietest airplane on the field. Lots of attention from
other pilots.
Don Walker
RV-8 N113BR
Renesis 4 port. RD-1c
EC-2 EM-2
Tuned 17.5 inch intake.
Tuned 24 inch exhaust into tangetial
premuffler
catto 76/88. Field elevation 5000 ft.
density 6200
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