Have you done the GAMI test i.e. checked that all cylinders reach peak EGT at roughly the same time as you lean?
I tried to observe this - it looks like they do. I have the feeling that old engine provided more power because 130 KIAS was something usual at 8000' with 2300/21".
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On flights to Skopje and back I took a closer look to EGT's and it seemed peaks were pretty much spaced.
2400/19" gave me 116 to 120 KIAS (peak EGT and ROP, 38 to 43 LPH) - TAS 140-144 kts, FL110, OAT +6 (altitude density approx 12000').
I'll check mag timing in next few days. Any other recomendation what to check?
On flights to Skopje and back I took a closer look to EGT's and it seemed peaks were pretty much spaced.
What do you mean? You have a big or a small GAMI-spread? It should be no more than 0.4 or 0.5 gallons. Ideally less.
One thing to remember: even though it will cost you a little speed, the most efficient mixture settings are somewhere between 30 and 70F LOP ( of course , alwaysreferred to to richest cylinder). Peter will say that it doesn't matter whether you run at peak or lean of peak, because all fuel is burned anyway, but the textbook (and relative charts) say that BSFCmin comes slightly LOP. Can't explain you why.
Other things to look for if looking for more speed:
-ball perfectly centered? Has the ball been calibrated?
-aircraft nicely clean (including undersides of the wing, the prop blades, etc.?)
-gear fully retracting? Flaps fully retracting? (a big one on Cirrus airplanes)
-alignment of spinner and cowling (usually not so much an issue on TBs, much more so on Mooneys)
-general "rigging" (alignment of control surfaces)
-CG sufficiently aft?
Just for comparison, yesterday, with a recently cleaned and polished airframe, I managed 170KTAS on 12.1GPH at FL110...and that was with the gear extended! :-))
Peter will say that it doesn't matter whether you run at peak or lean of peak, because all fuel is burned anyway,
No idea why I should say that because as stated that's complete nonsense!
What I would say is that while best SFC on a (any) petrol engine is about 25F LOP, the SFC curve in that region is very flat and it doesn't affect your MPG measurably whether you fly at 25F ROP or 25F LOP. I have done extensive flight tests on this.
So flying at approximately peak EGT is fine for getting the best MPG.
Some notes here.
Other effects e.g. using a low RPM are second order effects, though using a lower RPM can give an extra few %.
170KTAS on 12.1GPH at FL110
And so you should - 170 TAS at 11k is only about 144 IAS which a TB20 should definitely do on 12.1 GPH.
Just for comparison, yesterday, with a recently cleaned and polished airframe, I managed 170KTAS on 12.1GPH at FL110...and that was with the gear extended! :-))
Jealous 
What do you mean? You have a big or a small GAMI-spread? It should be no more than 0.4 or 0.5 gallons. Ideally less.
It seems that it is in that range but I thought it should be less. Calibrating ball could help but during last 15 flight hours (in last 7 days) I tested many settings and I noticed it was slightly off but I could keep it in proper position with rudder trimer. Anyhow the difference was 1-2 kts nothing more. Peter is talking about 10 kts. Other things seem to be right - they are as same as before I guess nothing has changed in aircraft rigging by itself.
Yes the speed loss in this case is quite substantial.
I know of three TB20s which all do the same speed i.e. close to 140kt IAS at low level, 11.5GPH. One is an early 1980s (but new engine), one is early 1990s I think, and the 3rd is my 2002 one. My engine is completely factory standard, no polishing of inlet manifolds, etc.
It could be a combination of things. Maybe 3kt for the TKS, 2kt for rigging slightly out, 2kt for extra aerials (antennae), 3kt for landing gear not all the way up...
Are the aileron trim tabs straight or bent? They should be straight.
Also if you fly alone, your LH tank needs to be quite a bit lighter. On the later (accurate) fuel gauges it is about 7-8mm down on the gauge, to balance the plane.
170 TAS at 11k is only about 144 IAS which a TB20 should definitely do on 12.1 GPH.
Huh?
Correction on the TAS-IAS conversion...
But we did this before - here.
Emir needs to check a few things. However the most basic thing, which is nothing to do with anything on the airframe, is what fuel flow his engine EGT-peaks at. At say 2000-3000ft, 23"/2300 or 23"/2400 it should peak at about 11.5GPH. If it peaks at 12.5GPH there is something not right. That is about a 10% error.
The magneto timing check will be done this weekend. In the mean time here are some more results more-less confirming previous ones:
8000', OAT +15, density altitude 9500', 2300/21":
- peak EGT - IAS 120, TAS 140, 38 LPH (10 GPH)
- ROP - IAS 122, TAS 142, 45 LPH (12 GPH)
It's me again with this boaring issue of mine
Magneto timing checked - OK, spark plugs cleaned (they were not so OK before) and the result was slight improvement at least measured at 2000'. POH specifies speeds without antenna.
Best power:
- 2400/23.8" - according to POH 148 KIAS (60.4 LPH), I get 140 KIAS (58 LPH)
- 2300/23.3" - according to POH 144 KIAS (56.5 LPH), I get 135 KIAS (54 LPH)
Best economy:
- 2400/23.8" - according to POH 145 KIAS (51.9 LPH), I get 135 KIAS (49 LPH)
- 2300/23.3" - according to POH 142 KIAS (48.5 LPH), I get 131 KIAS (46 LPH)
