LOP operation for IO360A3B6D

[bd32322]

If you have an induction leak in a LOP engine it will not run smoothly LOP. This is your clue something is not right. Finish the flight well ROP and a low power setting and investigate. An induction leak in a ROP engine is masked by the ROP. The leaking cylinder will run leaner than the others, and 50 ROP might put it at peak, where, depending on the % of power, can very well ruin it Especially at takeoff power. My friend's Bonanza runs 440 CHT's on takeoff and climbout. How small of an induction leak will make it run hotter, say 550 degrees?

our 201 loses exactly 5.6 knots (154.7 to 149.1 KTAS) to go from 80 ROP to 25 LOP at 7000'. FF drops from 11.7 GPH to 9.8 GPH. CHT drops 30 degrees. NM/GAL goes from 15.01 to 17.1, or a 14% improvement. Actually 15 LOP is only 4 knots slower on another .1 GPH FF.

Flat engines have been plagued by valve problems and early top overhauls longer than I have been alive, yet LOP is a rather new thing. Its caused from either running inside the "red box" at too high a power setting, too high of a CHT, or improper machine work on the valves. This is not an exhaustive list of causes.

If there is an induction leak, isnt it safer to run LOP instead of ROP. With rop and a leak you might get into the bad iperating region aka red box. But running LOP you'll only go further LOP. might run a bit rough but no harm done..?

[DaV8or]

If there is an induction leak, isnt it safer to run LOP instead of ROP. With rop and a leak you might get into the bad iperating region aka red box. But running LOP you'll only go further LOP. might run a bit rough but no harm done..?

Exactly. Ask yourself how blowing more air on an open candel reacts. Does it melt the candle down, or does it just go out? Remember, when LOP, there is no more fuel, so since it's the fuel that actually contains all the energy, how does more energy enter this equation?

[bd32322]

Exactly. Ask yourself how blowing more air on an open candel reacts. Does it melt the candle down, or does it just go out? Remember, when LOP, there is no more fuel, so since it's the fuel that actually contains all the energy, how does more energy enter this equation?

Right .. So the leaky cylinder should run even cooler (CHT) than its brethren and i think there should be no valve damage because those reside in the cylinder head which is cool. This implies that one can run ROP for speed only if LOP operation is smooth and works fine first, at least in the IO360 .. Never thought like that.. Interesting

[jetdriven]

The problem is that it wont run smoothly LOP. The problem is magnified with the throttle less than WOT. Do the GAMI hi-low test to determine induction leaks.

[bd32322]

The problem is that it wont run smoothly LOP. The problem is magnified with the throttle less than WOT. Do the GAMI hi-low test to determine induction leaks.

Would depend on the magnitude of the leak I think. I believe i have a leak, had posted in another thread. A high low test is on the cards his week. Mine runs smoothly LOP but at a higher fuel flow 9 gph at 8000 feet instead of 8.5 that it used to do before. And there is a lower than normal cyl 2 CHT but still above 300 F. So prolly a minor leak.

[Cruiser]

I have been running LOP exclusively now for a couple of years and love what it has done for my engine. In addition to the increased efficiency, my oil consumption has gone down and the oil is visually staying cleaner longer. I have noticed, too, that the end of my tail pipe has a white stain on it now that wasn't there before which I have assumed is related to the LOP ops. Has anyone else observed this or can explain it?

Jim

Pb

[fluffysheap]

I suspect it's always there, but you don't see it if you run ROP because it's mixed with much more carbon soot. LOP, no soot, all that's left is the lead.

[231LV]

You can tell how the engine was run by looking at the exhaust stain on the belly. A white/yellowish stain indicates LOP operation. A brown stain indicates ROP operation. Be suspicious of oily stains.

José

I wish! I have never run my engine ROP except climb to cruise altitude with everything forward. At cruise, LOP....my exhaust is dirty brown on the nose gear door....know why? Excessive rich low idle....even pulled back, the mixture on the ground emits that nasty brown stain