Just Completed APS Engine Management Online Course

[KLRDMD]

Quote: ehscott

0pm.  I tried operating LOP but it was not smooth.  He looked at my max fuel flow and it is too low.  Running at 20.3gph at WOT and full rich.  Need to get that dialed up a bit even though it is within book values.  My EGT difference was 90 dF.  I think I need some engine and injector tuning before I will be able to run LOP. 

[Earl]

Mine is a Mooney 252 (1986 M20K).

[KLRDMD]

Quote: ehscott

Mine is a Mooney 252 (1986 M20K).

[Jeff_S]

Yeah Earl, I had a single-purpose mission today to test out this LOP stuff, so I just headed northeast out of PDK toward Habersham for testing at 5500', then back home. I was playing hookey from work so I didn't stay out long. I did practice a touch of airwork just to see how much adverse aileron yaw the Mooney gives compared to my old Warrior. It turns out, not as much, although some Dutch rolls are always a good way to practice "yoke and rudder" technique.

[Earl]

Quote: KLRDMD

They usually can be made to run LOP well.

[KLRDMD]

Quote: ehscott

They usually can be made to run LOP well.

[Earl]

Thats what the guy at the MSC said as well.  That's my next step in the process. 

[dtcom]

My mechanic said that part of the fuel's job is lubrication.  He said that the lead in the gas lubricates the valve guides, and if you run lean of peak, there is less lubrication and the valve guides will fail prematurely.  He worked at Mattituck rebuilding engines for several years.  Any comments?

[danb35]

How does the lead in the gas get to the valve guides to lubricate them?  How many airplanes with mogas STCs have had this trouble?  I'd think that if the lead in 100LL contributed to (or was required for) lubrication, the FAA wouldn't have issued the mogas STCs.

[Shadrach]

Quote: KSMooniac

 The most efficient setting is in the 40-50 dF LOP range, but 25 dF is pretty good while retaining a good amount of cruise speed.  In my plane, I'll typically aim for 20 dF LOP when above 7,000 feet, but in the summer sometimes I need to lean further to keep CHTs below 380 dF.

[dtcom]

Quote: danb35

How does the lead in the gas get to the valve guides to lubricate them?  How many airplanes with mogas STCs have had this trouble?  I'd think that if the lead in 100LL contributed to (or was required for) lubrication, the FAA wouldn't have issued the mogas STCs.

[Shadrach]

Quote: dtcom

 MOGAS has an additive to lubricate the valve guides.  When they first came out with unleaded gas, many cars developed valve guide problems, and they then added some benzene derivitive for lubrication.  This is not in avgas.

[jlunseth]

Just a note after reading the first few posts in this thread.  I took the live course last summer.  For turbocharged piston engines, the advice was to run 125 ROP or 60 LOP at higher power settings.  As someone noted, under 65% pretty much anything goes.  Also, don't forget, when setting the engine based on %HP, the %HP is directly a function of fuel flow when LOP, and not a function of MP.  What multiplier to use depends on the compression of your particular engine.

[FBCK]

Some mention the "Turbo Guys" forum, I cant seem to find it and would like to read alittle bit about LOP in a turbo, could some direct me that way.

[KSMooniac]

Quote: dtcom

My mechanic said that part of the fuel's job is lubrication.  He said that the lead in the gas lubricates the valve guides, and if you run lean of peak, there is less lubrication and the valve guides will fail prematurely.  He worked at Mattituck rebuilding engines for several years.  Any comments?

[KSMooniac]

Quote: Shadrach

Hi Scott,

I've never taken any of APS's courses and I'm wondering if they covered if/how BSFC moves along the mixture curve. It seems that you're suggesting it's stagnant at about 50LOP and I've always thought that it moved a bit toward peak as manifold pressures drops. What say you? 

[KSMooniac]

Quote: FBCK

Some mention the "Turbo Guys" forum, I cant seem to find it and would like to read alittle bit about LOP in a turbo, could some direct me that way.

[jlunseth]

Quote: KSMooniac

I've never heard of such a forum if that is what you're asking... the APS course covers the full range of engine management for aircraft engines, including turbos, so I'd point you that way if you want to learn.  A free teaser can be had by reading everything from John Deakin on Avweb.com, but the APS course is money extremely well-spent for any aircraft owner.

[jetdriven]

Quote: fantom

As I posted earlier, those are my usual settings......100 ROP; 20-30 LOP.

IIRC, the EGT riase LOP is about 50F. Not a big concern, but hotter isn't better. And yes CHT is peak ICP is lower, which is much better.

Scott, are you using the 14.9 factor, to come up with power%?