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Lean-of-peak WITHOUT balanced fuel injectors?

rdv

By rdv
in Vintage Mooneys (pre-J models)

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DaV8or Grand Master

DaV8or

Posted
Posted

Here's the thing Dave,

You can run your engine anywhere you want. If running per the POH "recommendations" is the only way you want to go, great. That being said, The OP in this case want's to learn about LOP which will most likely lead to a greater understanding of how his engine works. He's asked about it and is getting responses.

Shadrach Grand Master

Shadrach

Posted
Posted

Quote: scottfromiowa

Any suggestions on fuel flow during climb that is sweet spot for I0360A1A?  At what altitude do you start to lean?  It seems that using fuel flow vs. EGT would be easier in climb.  Thoughts/strategies?  When I tried leaning in climb (before) using EGT I think I was to aggressive as cylinder temps started climbing...This was pre-fuel flow monitor (installed in December).  I do a cruise climb 120MPH with cowl flaps open.  My fuel flow is about 15gph running 2650RPM.

jetdriven Grand Master

jetdriven

Posted
Posted

Quote: Shadrach

Scott,

what is your take-off FF?  Full rich should be around 18 - 19gph at 2700.

I have experimented with LOP climbs, and have not found much utility in doing so for a few reasons.

1) At slower climb IAS (typically 120mph just like you), I have to be pretty lean to keep CHTs under 350 (which is were they run ROP target EGT method), the power drop is noticeable and I don't like the reduced climb rate. 

2) If i get distracted or I am busy with ATC I could conceivably climb my way into the red box.

3) ROP Target EGT method is easy with little to no risk of over-temping your engine.

4) ROP Target EGT gets you to cruise alt as quickly as possible.

If I was flying a turbo with an automatic waste gate, my opinion might very well change... 

Shadrach Grand Master

Shadrach

Posted
Posted

Quote: jetdriven

Our full rich SL, full throttle 2700 RPM FF is 18.2 GPH.  CHT level altitude at SL like this is 365, so we can't go leaner.

We start leaning around 1000' to the target EGT, which on #1, 2, or 3 is 1385 dF. Fuel flow and percent of power decreases with altitude.     CHT around 360-380.   

We cruise climb ~120 MPH with cowl flaps trailed, if changing altitudes in cruise try leaving them closed and climb at 10 MPH less than cruise airspeed. 

I havent tried LOP above 75% power but M20J doesnt climb well at reduced power, the most LOP WOT power you could make staying out of the red box is 80-85%, so I dont think it will work well in an NA IO-360.

YMMV

 

jetdriven Grand Master

jetdriven

Posted
Posted

WOT fuel flow on the RSA-5 fuel injection is not adjustable. 1385 EGT is like 250 ROP at that setting, so I thought it was just right.  I havent tried a LOP speed run down low, full rich, 2700 RPM and WOT it indicates 183 MPH. 

Shadrach Grand Master

Shadrach

Posted
Posted

Quote: jetdriven

WOT fuel flow on the RSA-5 fuel injection is not adjustable. 1385 EGT is like 250 ROP at that setting, so I thought it was just right.  I havent tried a LOP speed run down low, full rich, 2700 RPM and WOT it indicates 183 MPH. 

jetdriven Grand Master

jetdriven

Posted
Posted

Mine peak at around 1610 at 75% power, about 1580 for 65% power. I really like the RSA-5 injection, our GAMI spread is too small to measure. We have mostly been messing about locally in it, but our GPH average is about 8. 

scottfromiowa Grand Master

scottfromiowa

Posted
Posted

I have the GEM 602 monitor that ONLY has bar scales.  NO DIGITAL TEMPS.  I CAN NOT USE an EGT number as a reference for leaning in CLIMB.


So because the value changes as you climb I can't pull mixture at a specific altitude using fuel flow as a reference?  Is this correct?  I was NOT experimenting with LOP in the climb at full power, but just trying to reduce fuel flow "a bit".  Only tried once and as stated saw cylinder temps rise so put it back full rich and forgot about pulling mixture in climb...I have talked to insight and they plan...in the future...to introduce a G3 specifically for leaning (without all probes) for a reduced $ amount.  I plan to pursue this plug and play option down the road.


I had hoped to pull for a fuel burn "GPH measurement" vs using EGT as method (602) for leaning in climb...

danb35 Mentor

danb35

Posted
Posted

Quote: scottfromiowa

I have the GEM 602 monitor that ONLY has bar scales.  NO DIGITAL TEMPS.  I CAN NOT USE an EGT number as a reference for leaning in CLIMB.

[snip]

I had hoped to pull for a fuel burn "GPH measurement" vs using EGT as method (602) for leaning in climb...

jetdriven Grand Master

jetdriven

Posted
Posted

we also have an alcor single point egt that is straight up in the middle at takeoff.  lean to that value for climb, until you drop below 25" MP while full throttle, then you can lean a little more even.

scottfromiowa Grand Master

scottfromiowa

Posted
Posted

'64 M20E that is exactly how I lean in cruise.  Big pull then enrichen to first cylinder to peak then pull to 50 degree drop on EGT as indicated.  I didn't think about that being the "Richest" cylinder, but as I am doing it backward (already LOP) and enrichening I suppose that is what I am finding the "richest" cylinder.  I was running 80-100 LOP until recently.  I have picked up some speed and flying at 10GPH indicated.

jetdriven Grand Master

jetdriven

Posted
Posted

Quote: scottfromiowa

'64 M20E that is exactly how I lean in cruise.  Big pull then enrichen to first cylinder to peak then pull to 50 degree drop on EGT as indicated.  I didn't think about that being the "Richest" cylinder, but as I am doing it backward (already LOP) and enrichening I suppose that is what I am finding the "richest" cylinder.  I was running 80-100 LOP until recently.  I have picked up some speed and flying at 10GPH indicated.

Lood Mentor

Lood

Posted
Posted

Quote: jetdriven

if you are 50 LOP and at 10 GPH you must be at 75% power or higher, and that woud take 2500 RPM and ~27" of manifold pressure to do it.  Ours at 25-25 and 50 LOP is somewhere i the 9 GPH range.

scottfromiowa Grand Master

scottfromiowa

Posted
Posted

I flew to Arkansas at 6500 feet full throttle and 2500 RPM.  Did "Big Pull" to  engine rough and enriched to peak.  Pulled mixture until I dropped two bars.  25 degrees/bar=50 degrees LOP.  Fuel flow at that altitude was between 9.0&10GPH on fuel flow.  Just flew at 3500 feet 25 squared and leaned using same method.  Fuel flow was9.5-10GPH indicated...


I JUST had panel re-done in December and have only done a couple cross country flights this Spring.  My flying gets going right now.  I will be experimenting more with GPH as I do longer higher cruise flights.


I do NOT fly above 2500MP except in climb, ever.  I will definitely be taking a look at fuel flow in climb and at what RPM I am getting at full power Now that I have a digital tach and MP gauge as well as fuel flow.  My engine has NEVER shown a cylinder at 400 degrees (or higher) on the GEM.

Shadrach Grand Master

Shadrach

Posted
Posted

Quote: Lood

if you are 50 LOP and at 10 GPH you must be at 75% power or higher, and that woud take 2500 RPM and ~27" of manifold pressure to do it.  Ours at 25-25 and 50 LOP is somewhere i the 9 GPH range.

KSMooniac Grand Master

KSMooniac

Posted
Posted

Ross is correct... flying LOP in a normally aspirated bird requires some thought because it is NOT just a single setting like 50 LOP.  50 LOP is appropriate for ~75% power, but if you're above 7,000' density altitude you're not going to make 75% at 2500 RPM so you can be less LOP... perhaps only 25 LOP or so.  At 9,000' D.A. then going to 5 LOP is appropriate.  If OAT is high and your CHTs creep above 380, then you can lean a little more to get them below 380.


Keep experimenting!  Just make sure you understand the dynamics going on inside the combustion chamber and don't get fixated on a single setting...

scottfromiowa Grand Master

scottfromiowa

Posted
Posted

Thanks.  Good stuff.  All makes sense.  I try and get high, but as a Midwest VFR pilot the weather often dictates that I stay lower.  I am looking forward to experimenting...Laughing further.  Easier to document/compare now that I have digital read-outs that include fuel flow.


Scott

1964-M20E Grand Master

1964-M20E

Posted
Posted

Quote: scottfromiowa

'64 M20E that is exactly how I lean in cruise.  Big pull then enrichen to first cylinder to peak then pull to 50 degree drop on EGT as indicated.  I didn't think about that being the "Richest" cylinder, but as I am doing it backward (already LOP) and enrichening I suppose that is what I am finding the "richest" cylinder.  I was running 80-100 LOP until recently.  I have picked up some speed and flying at 10GPH indicated.

Shadrach Grand Master

Shadrach

Posted
Posted

Quote: scottfromiowa

'64 M20E that is exactly how I lean in cruise.  Big pull then enrichen to first cylinder to peak then pull to 50 degree drop on EGT as indicated.  I didn't think about that being the "Richest" cylinder, but as I am doing it backward (already LOP) and enrichening I suppose that is what I am finding the "richest" cylinder.  I was running 80-100 LOP until recently.  I have picked up some speed and flying at 10GPH indicated.

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