hypothetical scenario with estimated values:

 

Flying at 15000' going east, WOT, 2400 RPM, 14.5-15.5 GPH, 220 to 230 kts ground speed with 30 kt tailwind; EGT @ 1260, CHT @330.  Fuel computer says 900 nm of gas left, 1000 nm to go, takes about 1hr to land, fuel, and get back up in the air.

 

To make the trip without landing, lower RPM to 2100, begin aggressive leaning, engine sputters @ 9 GPH, enrich to 10 GPH, EGT's go up to 1300, CHT's to 350, GS ~ 190-195 kts with same tailwind. Now fuel computer says 1200 nm left, 1000 to go, have fuel margin and do not have to land.

 

Am I hurting my engine with the aggressive leaning??

Eugene,

 

I also agree with George and Walter - You won't hurt the engine at such a low power setting.

 

Of course, with all that time aloft I might think about it a different way.

 

A) At 225 GS and 15 gph it would take 4.4 hrs and 66.7 gals but there is only 60 gal aboard.

 

B) At 192 GS and 10 gph it would take 5.2 hrs and 52 gals leaving a 45 min reserve (8 gal) at that power setting.  The fuel computer would have said 1150 nm could be made at the fuel burn rate.

 

Scenario B, while only about 50 minutes longer, would be right at the safety margin and would assume the winds don't change for the worse thus forcing a landing anyway.  Hmmmm, 1000 nm and no wind or weather change.

 

Scenario A would see me land after about 2.5 hours and re-fuel, empty fluid accumulations, check the weather, have a coffee with the airport bums, stretch my legs and fly the next leg with no worry about the winds, fuel reserves or limiting my options.  Of course I would have used about 15 more gallons of fuel (@ $3/gal, $45 more + refreshments) and put less time in my log book even though I got there just 10 minutes later (if no wind change).

 

I have flown LOP to eliminate a stop, but with ROP IFR reserve margins.  I dealt with the fluid buildup an alternate way and used the ADF, tuned to C&W stations, to reduce the monotonous hum of an idling engine.  I also have a bias against sitting for more than 3.5 hours without a break, thrombosis issues aside.  Maybe I could rent a 'Vette to make up for lost time.

 

BTW, (A) had the engine turn over 633,600 times while (B) runs that up to 655,200.  That's a lot of clanking around.