LOP Impact on TBO

[201er]

On one hand LOP saves gas, but has anyone considered the impact on value of the plane (specifically engine)? If LOP is better for the engine and helps it make it to or past normal TBO, that's great if you're keeping it. However, if LOP results in a net speed loss, that means you're taking more time to get there and therefore putting more hours on the engine. You saved on gas, took more time, but also put a little more time on the engine. Just like the gas savings, this time adds up in the long run. So does the gas saving still outweigh the deduction in engine time for resale value? Has anyone considered this?

[jetdriven]

It srtill gets more MPG, and that is less lead and combustion products in the oil per hour.  Sure, a 2100 hour engine adds zero value to the airplane, but fly it to 2400 hours, find somethinig wrong, then overhaul it.  the 400 hours past TBO are free, thats 5K.   if you run it LOP from a fresh OH thats a free engine altogether.

[Bolter]

Quote: 201er

On one hand LOP saves gas, but has anyone considered the impact on value of the plane (specifically engine)? If LOP is better for the engine and helps it make it to or past normal TBO, that's great if you're keeping it. However, if LOP results in a net speed loss, that means you're taking more time to get there and therefore putting more hours on the engine. You saved on gas, took more time, but also put a little more time on the engine. Just like the gas savings, this time adds up in the long run. So does the gas saving still outweigh the deduction in engine time for resale value? Has anyone considered this?

[jetdriven]

Save 1.5 GPH at 5$ a gallon, thats $7.50 an hour.     $7.50 x 2,000 = 15,000$

almost a free engine.

 

[Shadrach]

Quote: 201er

On one hand LOP saves gas, but has anyone considered the impact on value of the plane (specifically engine)? If LOP is better for the engine and helps it make it to or past normal TBO, that's great if you're keeping it. However, if LOP results in a net speed loss, that means you're taking more time to get there and therefore putting more hours on the engine. You saved on gas, took more time, but also put a little more time on the engine. Just like the gas savings, this time adds up in the long run. So does the gas saving still outweigh the deduction in engine time for resale value? Has anyone considered this?

[Jeff_S]

Quote: 201er

On one hand LOP saves gas, but has anyone considered the impact on value of the plane (specifically engine)? If LOP is better for the engine and helps it make it to or past normal TBO, that's great if you're keeping it. However, if LOP results in a net speed loss, that means you're taking more time to get there and therefore putting more hours on the engine. You saved on gas, took more time, but also put a little more time on the engine. Just like the gas savings, this time adds up in the long run. So does the gas saving still outweigh the deduction in engine time for resale value? Has anyone considered this?

[Parker_Woodruff]

Lower pressure in an engine sure can't hurt. 

[201er]

Quote: Jeff_S

Mike, I hereby nominate you as the winner of "Most Inquisitive" on the Forum. I am amazed at the things you think of. I don't say this to be condescending or rude, and I sense that you are really enjoying getting to know your Mooney and all the idiosyncracies of airplane operation.  I just hope that somewhere in all this you get out and just fly your airplane and enjoy the amazement of cruising along with the birds. At some point all the technical mumbo jumbo goes away and you just start to appreciate the sheer joy of flying, without analyzing.

No offense meant, so please don't take any. Tailwinds!

[201er]

Quote: Shadrach

1) Your premise is flawed. There is no statistical data to show that LOP ops will have any affect on TBO. Even the most staunch proponents of LOP ops will tell you that.

Sure, presuming TBO is TBO is 2000... if you fly slower while turning the prop at the same speed, you'll bring your engine closer to the TBO time in order to cover the same distance.

2) Even if you could quantify the difference is a plane with an engine that has gone 300,000nm in 2000hrs going to be worth less than a plane that has gone 300,000nm in 1900hrs?

Well, we know how engine time plays a role in appraising an airplane. Since the buyer can't accurately assess the inners of the engine, they have to look at the hours.

3) The number of air miles logged per engine is affected by so many variables (wind, routing, holds, restricted areas) as to make the 4 to 6kts you lose by "properly" running LOP (those of you running still 50LOP at 8500 take note) a rounding error.  Additionally, for shorter VFR flights below 3500ft speed difference LOP vs ROP is very, very small, however savings in FF can approach 40%. Are all of your flights purely travel based?  Is a 1hr joy ride anymore satisfying at ~160kts vs ~155kts? Is that same joy ride more satisfying at ~16.5GPH vs ~10.5GPH? 

Wow. I am simply amazed to what lengths people are willing to bend the numbers in order to justify their point of view. 16.5GPH??? Really? Where did you get that from? Both you and I are flying IO-360s. Even for 75% cruise at 100ROP (not 50 or 25), it burns 12.5gph at sea level in the most inefficient configuration possible! 75% power LOP on the other hand would burn 10gph. That's only 20% savings. Once you factor an efficient ROP cruise at 10.5GPH 25ROP vs 9-10GPH 70-75% power, the difference isn't particularly big at all.

While I appreciate the lower temperatures and gas savings, I don't think it's necessary to pretend like it makes THAT big of a difference in fuel savings on our 200HP engines.

[xftrplt]

Quote: 201er

So does the gas saving still outweigh the deduction in engine time for resale value? Has anyone considered this?

[Shadrach]

Quote: 201er

 

[jetdriven]

For us at low altitude, on a stock 201, is full throttle at sea level full rich nets 335 CHT at 17.5 or 18 GPH.  leaning slightly nets 380 or more, saving 1/2 GPH.

 

Going to the lean side, it must be at 10 GPH or less to keep CHT below 380