What is your DA40's hottest cylinder?

[Chris B]

I am working with GAMI to tweak my engine settings. One bit of information that John-Paul requested is "typical" DA40 behavior during initial climb. Presumably DAN is the right place to ask! Items 1 & 3 are most important, but if possible, the rest will help provide context.

On initial (sea level) climb after dumping flaps:

1. Fuel flow?
2. IAS?
3. Hottest cylinder & CHT?
4. Coolest cylinder & CHT?
5. Power Flow (Y/N)?
6. GAMI injectors (Y/N)?
7. Tweaked baffles, e.g. with RTV (Y/N)?
8. EIS (Y/N)?

FWIW, here is my aircraft (sample flight):

1. 17.5 gph
2. 95 kts
3. #1, 380-390F
4. #2, 360-370F
5. PF: Y
6. GAMI: Y
7. RTV: Y
8. EIS: Y

Thank you!

Chris

[waynemcc999]

1. 15.5 gph (as CHTs remain <390F, I then in steps lean back to 14 gph thru the rest of the climb)
2. 75 KIAS, then stepped to 80 KIAS and eventually 85 KIAS
3. usually #1; I adjust Mixture to keep below 390F in initial climb, and then 360F in cruise climb
4. not sure, probably #2; approx 370F initial and 340F cruise climb

5. PF: Y
6. GAMI: N (conducted GAMI test, sent to GAMI, they indicated stock injectors were fine)
7. Tweaked Baffles: N
8. EIS: Y (ElectroAir)

[blsewardjr]

15.5 gph
95 kts/2400rpm (for cooling, prop ok to 2700)
#1 385-395F
#3 355-365F
PF: Y
GAMI: Y
RTV: Y
EIS: N

I recently re-tweaked the baffles and saw only 375 as the hottest in a full power (2600 rpm) climb on the way home so may have different number soon

[Rick]

Field elev 1175'

at 1000' AGL:
Fuel flow? 16.5
IAS? 86
Hottest cylinder & CHT? #1 364
Coolest cylinder & CHT? #2 353
Power Flow (Y/N)? Y
GAMI injectors (Y/N)? Y
Tweaked baffles, e.g. with RTV (Y/N)? N
EIS (Y/N)? N

at 2000' AGL:
Fuel flow? 16.0
IAS? 89
Hottest cylinder & CHT? #1 376
Coolest cylinder & CHT? #2 361

FYI - #1 is always my hottest CHT, #3 & #4 are almost always equal, and #2 is always slightly less than 3 & 4.

[astaib]

Hello,

What is baffle tweaked please?

My 1 is always hotter.

My baffles and seals are old and a bit damaged.
I’m thinking about changing them, do you think that it will help to cool down the cht ?

Arnaud.

[Kurt h]

1. 16 GPH
2. 75-85 kts depending on load, temps
3. #4, 400 deg. F. (old baffling, was 380 a few years back)
4. #2, 350 deg. F.
Power Flow (N)
GAMI injectors (N)
Tweaked baffles, e.g. with RTV (N)
EIS (Y)?

[Rich]

This may not be helpful, but the best I can figure:

1. 17.4 GPH
2. 80
3. 1-3 are all together, too tight to differentiate
4. 4
5. Y
6. N
7. N
8. N

1-4 need clarification. The CHT's slowly climb after takeoff. It takes awhile for them to peak out, and typically it doesn't happen until I've leveled off. Fuel flow is adjusted during the climb to try to maintain ~1300 deg EGT. I normally allow airspeed to climb as AGL increases. Rarely do I have a need to claw for altitude for very long.

#4 cylinder is always the coolest, by about 20 degF. #4 EGT is also always the lowest, be it climb or cruise, so these are consistent with each other. Actual CHT values are greatly affected by OAT. The GAMI lean test shows all cylinders peaking at very close to the same fuel flow with stock injectors, which is the real goal of GAMIs.

In reality these days I rarely get to depart from sea level, so initial fuel flow is lower, around 16-ish. It's also worth noting that my lowest temperature cylinder changed years ago upon installing the PowerFlow. I actually don't remember which it used to be, but it's been #4 consistently ever since.