In piston GA, range always trumps speed 
Especially in Europe where anything related to the ground tends to involve hassle and delays.
That’s why the TB20 is so great. Shoreham to Dubrovnik is doable in still air although I prefer the usual tailwind for extra margin.
My own preference is that these big bore air cooled engines like to be operated at 65% or 75% power.
What about NA 200hp IO360? hanging it around Carson speeds in 45% is it good for engine?
I usually fly 60% LOP, going 40% LOP give extra 300nm in calm air (about 25% uplift in range)
POH even lists 35%-40% ranges where one is probably flying best gliding L/D, the engine seems to run ok with 2000rpm but is that good to keep the engine warm and happy with 12h of flying?
The 36% is wat too close to (1950rpm, 17MP) limitation on propeller, theoretically that gives 1200nm on 64USG with taxi, takeoff, warm up and 45min reserves (let’s call that 900nm is possible on 36%)
depends on the mission, does it? For example, flying over body of water. :) Or over a country where landing is a paperwork hassle.
Yes it’s to avoid landing, arranging fuel and high prices (not planning to cross Atlantic or Pacific)
It’s also know your engine question, the aircraft has +1000nm range with 64USG but has nothing published for 98USG version (I gather +1400nm?) and it can fly 800nm non-stop but my question is: can you fly 40% power profile? (even with regular refuelling along your way or stops to stretch legs)
In piston GA, range always trumps speed
The best “speed modification” is long range if it saves ground and refuel hassles
That feeds into door-to-door speed measures
I always plan up to 5 hours, having in mind that I rarely fly alone and I’m aware that my passengers will appreciate end of flight or at least a break after 5 hours in small DA42 cabin. Calculating miles it’s 800+ NM, cruising 170+ KTAS, at 70-75%, consuming 12-13 GPH.
Is there any engine/propeller issues for say flying JetA burners like DA42 or DA40 at 45% power?
PS: I don’t fly more than 2h-3h with pob (with family we land, stretch, eat maybe sleep without need for fuel), now I am tempted by trip alone at 45% power 
Ibra wrote:
Is there any engine/propeller issues for say flying JetA burners like DA42 or DA40 at 45% power?
In general no problem but I don’t find it optimal.
Book numbers for my engines (2xCD-155 in DA42) are:
FL160:
- 75% – 166 KTAS, 12.7 GPH
- 45% – 129 KTAS, 7.2 GPH
FL120:
- 75% – 160 KTAS, 12.7 GPH
- 45% – 126 KTAS, 7.2 GPH
Real life numbers are a bit better, few knots faster but a bit more consumption for same power percentage:
FL160:
- 75% – 175 KTAS, 13.2 GPH
- 45% – 138 KTAS, 7.8 GPH
FL120:
- 75% – 169 KTAS 13.0 GPH
- 45% – 133 KTAS 7.6 GPH
792nm no reserve.
Its 170L @ 35lph @ 165kts
Lancair 320 on io-320-d1b.
Ibra wrote:
Is 45% range a useful figure? has anyone flown that slow with sole benefit to max range? is it good for engines to fly +12h at 45% power?
It depends on the mission, doesn’t it? I often put around 45-50 %. For example, I fly sometimes from Germany to an airfield in Spain without pump station. So I fly there (~850nm) and on the return flight make a stop in France. This is around 8-9 hours of flying time. In order to fly that long on 90 Gal without refuelling (plus reserve) I have to slow it down. But as gross total time it’s the best way of doing it and all my crew agrees on that.
Now during instrument training it’s not worth arriving fast. I need flying time. So we slow it down even a tad more, around 40% I think. Still around 135 knots true.
Asking about the engine, why shouldn’t that be the best way to run an engine? Not too cold, not too hot, you can’t do anything wrong with any setting, and it just runs and runs.
I am looking at same profile out in one leg with one fuel stop on my return…
While ago, I was told to keep good power setting on Lycomings as that helps to seal cylinder rings without excessive oil consumption
I guess this happens on some engines but not on others?
