hlangebro
Well Known Member
So, I have had high CHT's in climb since day 1 (410-425f). I was pondering about the fuel nozzle and wanted to check my egt's, fuel flow etc. So here are my test data from today. Cht's corrected for 100F day.
Engine is a O-320 D3G, 160hp, Whirlwind GA200, RV7A. Cowl flap.
On ground 1200rpm -60rpm increase from full rich to just before rough. Just about right.
Static; 2160rpm, 130hp, 81%, 12.8gal/hr. A little low for fuel flow...
Climb, cowl flap full open, full rich, 115kias:
cht: #1 393, #2 408, #3 391, #4 379
137hp, 85%, fuel flow 12.3gal/hr. Fuel flow seems low....
Cruise, 8500ft DA, WOT, full rich, cowl flap closed, no increase in rpm during leaning, 2730RPM, 77%, 124hp, fuel flow 13.2gal/hr
EGT's (from full rich to peak, delta F):
#1 88F, #2 96F, #3 127F, #4 151F
CHT (as indicated)
#1 352 #2 365 #3 354 #4 361
Conclusions....
Seems like it is running a bit lean, but not by much. I would say that an increase in fuel flow would definitely keep the cylinders cooler and I could potentially climb at a lower speed without hitting 400F. I'd like to stay below 380F.
I am pondering about re-jetting. One thing that I also need to double check is that the mixture lever actually opens fully. I have the James cowl with pressure plenum. I have sealed everything and checked for induction leaks, I have been modifying for about a year now, with some success, but I still haven't found the smoking gun... my guess is that the mixture is a bit too lean...
Engine is a O-320 D3G, 160hp, Whirlwind GA200, RV7A. Cowl flap.
On ground 1200rpm -60rpm increase from full rich to just before rough. Just about right.
Static; 2160rpm, 130hp, 81%, 12.8gal/hr. A little low for fuel flow...
Climb, cowl flap full open, full rich, 115kias:
cht: #1 393, #2 408, #3 391, #4 379
137hp, 85%, fuel flow 12.3gal/hr. Fuel flow seems low....
Cruise, 8500ft DA, WOT, full rich, cowl flap closed, no increase in rpm during leaning, 2730RPM, 77%, 124hp, fuel flow 13.2gal/hr
EGT's (from full rich to peak, delta F):
#1 88F, #2 96F, #3 127F, #4 151F
CHT (as indicated)
#1 352 #2 365 #3 354 #4 361
Conclusions....
Seems like it is running a bit lean, but not by much. I would say that an increase in fuel flow would definitely keep the cylinders cooler and I could potentially climb at a lower speed without hitting 400F. I'd like to stay below 380F.
I am pondering about re-jetting. One thing that I also need to double check is that the mixture lever actually opens fully. I have the James cowl with pressure plenum. I have sealed everything and checked for induction leaks, I have been modifying for about a year now, with some success, but I still haven't found the smoking gun... my guess is that the mixture is a bit too lean...
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