how to lean the mixture if..?

[Shadrach]

On a J, when at 4000' and 2200 RPM, you are at reduced power, but at higher RPMs you are not, you want to be below 65% HP, so after leveling out, set power, RPM as desired, then mixture...

Hmmm, I too fly an injected airplane. I never close the throttle unless I want to slow down or go down. It's an inefficient way to climb or cruise. With a carbed engine, you have fewer choices.

Back to your comment, I assume when you write "power" you're referring to MP. If you're trying to set a book power setting in an airplane with a CS prop, I think it's better to set RPM first. If you set MP first and then reduce RPM your you will have to reset the throttle...and then you will have reset mixture. At a given throttle setting, MP will rise when RPM is reduced.

[Hank]

Ross, I ALWAYS reduce MP first, then reduce prop! Going from 2700 to 2300 for a short trip will add back almost 1" of MP, so I just pull to 22" then set for 2300 and lean, it's good enough. If traveling, I'm much higher so MP reduction is just enough to make the MP needle move, set generally for 2500 and lean.

 

The MP reduction is to cock the throttle plate in the carb and hopefully create better fuel atomization and more homogenous mixture by inducing turbulent flow. You injected guys don't need to bother with this.

 

And TJ, the OP in this thread also flies a C so these things matter to him. Very few operational details are similar between the carbed and injected engines. For instance, 2200 is a redlined RPM for us; my redline is 2000-2250 with a 3-blade. The important part is to learn how your plane operates within your restrictions so that if something changes, you will notice and can compensate, then discuss with your A&P to get it fixed.

 

Ya'll stay safe out there.

[Shadrach]

I get it Hank,

 

But you're not really getting anything back.  The engine is just asking for less air through the same size orifice so (there is less vacuum) the Manifold Pressure reads higher (really a vacuum gauge).  

 

My only point was that if you are a POH power setting kind of a pilot.  It make sense to set RPM first as that will not be affected by changes to throttle or mixture unless the power is reduced beyond the low pitch stop. 

[ArtVandelay]

Yea Hank, I didn't explain it very well, basically I was saying is I set the engine to less than 65% HP first, whatever those numbers are for your engine, then you lean without worrying about hurting the engine, also pointing out you can't use altitude alone, at higher RPM, I'll be at higher HP, don't know if C has performance tables the J has.

[Shadrach]

Yea Hank, I didn't explain it very well, basically I was saying is I set the engine to less than 65% HP first, whatever those numbers are for your engine, then you lean without worrying about hurting the engine, also pointing out you can't use altitude alone, at higher RPM, I'll be at higher HP, don't know if C has performance tables the J has.

 

Can you post the performance tables for the J at 10,000MSL?  Id like to see how high you need to be before your Mooney becomes "unhurt-able".  My F apparently needs to be above 12,500msl before it becomes "un-hurtable". See attached.

[ArtVandelay]

Here you go...

[Shadrach]

Do you find it odd that my F will produce 12 more horsepower @12,500 then your J will at 12,000?

[ArtVandelay]

Do you find it odd that my F will produce 12 more horsepower @12,500 then your J will at 12,000?

And you do it with less fuel, which is a neat trick

Also, check out fuel rate at 10000, your fuel rate drops 26% but HP only drops 6%....another neat trick that defies the laws of physics

[Shadrach]

And you do it with less fuel, which is a neat trick

Also, check out fuel rate at 10000, your fuel rate drops 26% but HP only drops 6%....another neat trick that defies the laws of physics

My point in posting those performance tables was to show that the performance section of most POHs' would be best used on a perforated roll in the bathroom.

I think a solid engine monitor opens up a new world of safe and reliable power settings. I lean my engine where ever I decide to cruise whether that is 2000MSL or 12000MSL because I am comfortable monitoring the engine. The POH says it's fine to run 2350 at 24" 100 ROP, I agree that it is OK (though CHTs will be on the high side), but there are many power settings that are kinder to the engine and more efficient that are not recommended. I therefor set power based on what the monitor tells me, not the book. To each his/her own.

[ArtVandelay]

My point in posting those performance tables was to show that the performance section of most POHs' would be best used on a perforated roll in the bathroom.

I think a solid engine monitor opens up a new world of safe and reliable power settings. I lean my engine where ever I decide to cruise whether that 2000MSL or 12000MSL because I am comfortable monitoring the engine. The POH says it's fine to run 2350 at 24" 100 ROP, I agree that it is OK (though CHTs will be on the high side), but there are many power settings that are kinder to the engine and more efficient that are not recommended. I there for set power based on what the monitor tells me, not the book. To each his/her own.

+1 on the engine monitor, also allows you to lean as you climb

[Shadrach]

All anyone needs to lean as they climb is a single probe EGT gauge, and all us injected guys need to accurately set power LOP is a fuel flow gauge. On our IO-360s keep the fuel flow below 8.7 GPH and all will be well, although I prefer between 8 and 8.5 GPH personally. At low altitude you might have to retard the throttle a bit for smooth operation. It really is this simple for us injected guys if we are willing to restrict ourselves to below 65%. If you want to utilize higher cruise power settings you need an engine monitor to do it safely IMHO.

 

I don't think you "need" an engine monitor to safely set  LOP any more than ROP. I'd be OK flying an IO 360 down low at high power LOP based on airspeed changes, but only in the in the short term.  I think overall an engine monitor is key to observing long term trends.  As has been pointed out before, its even more important for ROP ops because a partially blocked injector during a high power climb on a hot and heavy day is the most probable to kill an Lyc IO360.