I wonder if the power curve is as flat at high altitude i.e. low MP?
One day I will do a test…
boscomantico wrote:
That’s why, when I’m trying to climb near the ceiling of the aircraft I fly 50-80 ROP, just to not waste any additional fuel.
@boscomantico @Peter
When you want to climb 50-80ROP, or whatever, when do you seek the peak and adjust accordingly ?
Then, when you have adjusted (being full throttle of course), you just let the setting as it is, for the whole climb ?
For my part, I usually climb at a fix FF (according to manual), then use the “LEAN ASSIST” in cruise. So I am not very familiar with what I read here.
Well, just lean to find peak and then enrichen again to about 80 ROP (the max power point). When you are near the ceiling of aircraft, you will be pulling very little power, so can’t harm the engine.
You will have to do that again after another 3000 feet or so, since the peak will slightly change with altitude.
If you know the orecise fuel flow to get 80 ROP at a given altitude, pressure and temp, you can also do it by reference to fuel flow, but by EGT is more precise, which is important if you need to sqeeze every HP out of your engine near its ceiling. But Peter is more of an expert on climbing into the stratosphere with an NA aircraft 
then enrichen again to about 80 ROP (the max power point).
Max power is a lot richer than that. It’s 125-150F ROP.
Try it in flight
I can’t find a difference in practice. And most of the famous graphs don’t bear this out. So i decide not to waste one GPH.
boscomantico wrote:
Well, just lean to find peak and then enrichen again to about 80 ROP (the max power point). When you are near the ceiling of aircraft, you will be pulling very little power, so can’t harm the engine.
I well understand that procedure which is what I usually perform in cruise.
My question is when do you do it during the climb ? From 5000ft ? 10000ft ?
When you say harming the engine, you mean leaning while the engine outputs a lot of its power ?
boscomantico wrote:
You will have to do that again after another 3000 feet or so, since the peak will slightly change with altitude.
Ok, that is what I thought: the peak change during the climb. So you advise to repeat the operation every 3000ft. How do you proceed then ?
Do you enrich a little first, before leaning again, up to the peak ?
boscomantico wrote:
If you know the orecise fuel flow to get 80 ROP at a given altitude, pressure and temp,
Really not handy, clearly the EGT is more precise !
Peter wrote:
Max power is a lot richer than that. It’s 125-150F ROP.
I think this is what I find in the manual of my C182 (IO-540 AB1A5). Don’t have personal test available.
My question is when do you do it during the climb ? From 5000ft ? 10000ft ?
Well, in the SR22, I will do that once above FL140. Below that, power is plentiful and I use the placarded full throttle climb fuel flows, which pretty much equates to the constant EGT method.
So, I will check peak at about FL140, then lean accordingly, and then recheck it again maybe when passing FL160 or FL170 and then climb to my final level on that setting. As you can see, this (i.e. having to sqeeze every HP out of the engine for the climb) is not required very often. Unless weathe, airspace or terrain dictates, I prefer cruising at FL100 or FL110 max.
boscomantico wrote:
Well, in the SR22, I will do that once above FL140. Below that, power is plentiful and I use the placarded full throttle climb fuel flows, which pretty much equates to the constant EGT method.
Ok so that would translate to FL100-120 maybe for my engine.
I now understand the procedure. Thanks !!
Lets agree on “roughly 100° ROP”.
Besides, as the post was originally about fouled plugs, what is your procedure when that happens ?
Leaning during taxing is obviously the best preventive action, but how do you cure if that happens during the mag check ?
It happens once or twice, and going higher power (2100 – 2200 rpm instead of 1800rpm), I lean the engine aggressively, and got each time the faulty plug back. Maybe not the good way ? How do you do then ?
