Great flight to Charlotte this weekend

[par]

It seems like my Mooney has been doing nothing but consuming money for past couple of months starting with its first annual (with me). The most exciting addition to the plane has been the EDM-830, which is working well now that all the bugs have been worked out. After a long week of crappy weather here on the east coast, I had a chance to take a "long" trip to Monroe Exec in the Charlotte area yesterday. I was looking forward to messing around with the EDM-830 on this flight to see how my engine actually performs in an extended cruise. I made a couple of discoveries and thought I should share my experience with the crowd.

First of all, the morning was relatively cold considering what we are used to in this part of the country. Overnight temps dipped in the high 30's and by the time I arrived at the hangar in the morning, it was still in the low to mid 40's. I had thought about stuffing two light bulbs into the cowlings the night prior but failed to do so. Sure enough, the engine did not want to start up in the cold and took several tries to get it running. After a warm-up/run-up, we got ready for T/O out of PVG. Being a C model, the CHT's are always a nail biter on T/O as I look to the EDM-830 to show me what the engine is doing. The average experience is always as follows: Cylinder #1 remains well under 380, #2 & #4 will approach and exceed 400 by a few degrees, while #3 is guaranteed to hit 420-440 depending on how warm the engine was at T/O. This day was no different with #3 approaching around 425 degrees on the first T/O of the day.

Having seen multiple people mention the secondary fuel jet on the C at max power, I have been conducting all my T/O's at WOT until level-off to take advantage of the fuel cooling. I will say, this makes a significant difference in the CHT's. When I take-off and pull power back from WOT for the climb, all my CHT's show higher than the above numbers. I always conduct a 120-140mph climb-out with cowl flaps fully open. I do not pull the prop back until I see 25" of manifold pressure, at which point the prop is set to 2500 for the duration of the climb. Can someone confirm is this is the accepted method? I was taught never to let MP exceed RPM during my transition training. Am I really doing any harm to the engine by pulling the prop back soon after T/O with MP>25"? This would certainly allow for more cooling.

Until yesterday, I practiced leaning the engine slowly in the climb. However, I paid close attention to the CHT's to see what impact this actually had. I noticed that even the slightest amount of leaning caused CHT's to increase. This of course is not ideal with #3 already being above desired values. So, the first lesson I learned yesterday was to avoid leaning the mixture until I am leveled off. I also noticed that as the mixture is leaned for cruise, my #3 CHT will initially spike but then it reaches a point where it will begin to decrease. Without any leaning, I am seeing temps in the high 390's on #3. Once leaned out, it comes back down to the 370's-380's. I really have not been able to get it any lower than that in cruise. However, I noticed something very odd as I did this yesterday. As cylinder #3 cools down after reaching some peak during the leaning process, #4 CHT will begin to rise and end up in the low 390's with the mixture leaned out ROP. Once again, the throttle remains wide open the entire time. I keep the cowl flaps open throughout the flight with a cruise setting of WOT/2400.

I did not have a chance to download the data yesterday but I will get it the next time I go to the hangar. I don't know how much more money I want to throw at the baffling at this point. I'm thinking that the money would be better spent on the new cowling mod when it becomes available. Looking for thoughts/personal experiences from you guys.

On another note, I took the Mooney to 11.5k yesterday for the first time and I was looking at 7.7gph in cruise at 150kts average GS...which was a welcomed sight.

[1524J]

Do you have bayonet style probes on all cylinders? The reason I ask, I had three bayonet probes but my #3 cylinder had a spark plug gasket probe which indicated about 50 degrees hotter. Once I changed to a bayonet probe it solved my #3 cylinder temp. concerns. 

[carusoam]

Par,  Nice collection of data and thoughts.

Did you mention your air speed during the climb?  Many C pilots use 120mias for improved CHTs.

Higher rpms provide more HP, burning more fuel, and requires more cooling...

Makes you want to review the dog house for all cracks, gaps or missing felt seals...

Makes you watch the thread on the new cowl being designed and built for classic Mooneys...

Having a JPI with FF and carb temp is a spectacular device.

Best regards,

-a-

[Hank]

Thanks for your data. I'd like to have a 4-point monitor one day.

I've made two XC trips at WOT (one trip, out and back). Fuel burn was up 15-20%, but speeds were quite similar to what I usually see. My next trip, of similar length (both were 2-2.5 hours each way), I reverted to my normal practice:

• Climb to altitude at Vy = 100 - Alt in thousands, Full Rich.
• Look up "Target EGT" to lean in the climb; I need to repeat mine since working on induction.
• Level off, accelerate to max airspeed, then pull throttle until MP needle moves (that's enough to shut off the enrichment circuit). Leave it there until descent.
• If at 7500 or higher, pull prop back to 2500. (MP + RPM < 47 for 65% power or less).
• Confirm settings with Performance Charts in Owners Manual (I keep copies on my kneeboard).
• Lean to 50°F Rich of Peak.
• When descending, I only push for 500 fpm and trim forces out. As I descend, occasionally pull MP back to cruise setting, and relean EGT to the cruise setting (both will rise while descending).
• This generally yields TAS ~ 170-172 mph, and 9 gph block time. My factory temp gages are near the top of the green, but still in the green stripe, not the space between the stripe and the Max temp lines.

 

Edited April 11, 2016 by Hank

[par]

21 minutes ago, 1524J said:

Do you have bayonet style probes on all cylinders? The reason I ask, I had three bayonet probes but my #3 cylinder had a spark plug gasket probe which indicated about 50 degrees hotter. Once I changed to a bayonet probe it solved my #3 cylinder temp. concerns. 

I opted to have the bayonet probes on all cylinder as my factory CHT gauge was inaccurate. The sparkplug gasket probe was indicating well into the 460's+, which is why I opted to switch to the bayonet on all cylinders for accurate data. I understand the primary instrumentation concerns behind this but once again, the primary gauge is not worth a $500 fix with continuing inaccurate data.

[par]

17 minutes ago, carusoam said:

Par,  Nice collection of data and thoughts.

Did you mention your air speed during the climb?  Many C pilots use 120mias for improved CHTs.

Higher rpms provide more HP, burning more fuel, and requires more cooling...

Makes you want to review the dog house for all cracks, gaps or missing felt seals...

Makes you watch the thread on the new cowl being designed and built for classic Mooneys...

Having a JPI with FF and carb temp is a spectacular device.

Best regards,

-a-

I do not climb at any less than 120mph. Most of the time, it is higher than 120. FF is def great to have and worth the cost of doing all this with the inherent risks involved in aviation.

[BDPetersen]

WOT after takeoff through climb was a concept Mooney was trying to instill 50 years ago. Amazingly, the power of the OWT (old wive's tale) remains strong. Yes, full throttle and back the rpm off of redline and you're good to go. It's not turbocharged. Nothing bad can happen.

[Marauder]

Par -- I fly an F so what I write may not be equivalent. I will leave everything firewalled and climb at 110 KIAS as starting point. If it is colder out, I may climb at 100 KIAS or if hotter, at 120 KIAS -- whatever will keep my cylinders below 380°.

When I bought my Mooney 25 years ago, I was taught the 25 squared climb setting. After I talk to Lycoming that the engine is designed to run full throttle and at red line, I changed how I flew.

Sent from my iPad using Tapatalk

[Browncbr1]

5 hours ago, par said:

I opted to have the bayonet probes on all cylinder as my factory CHT gauge was inaccurate. The sparkplug gasket probe was indicating well into the 460's+, which is why I opted to switch to the bayonet on all cylinders for accurate data. I understand the primary instrumentation concerns behind this but once again, the primary gauge is not worth a $500 fix with continuing inaccurate data.

The JPI 830, as far as I know is not certified for primary cht use.  It's actually only certified for primary egt.  Stupid, but this is why I use bayonet collar probes.  From what I understand, only the edm 900 series will let you get rid of your garwin instrument cluster.  

About your cht on climb, I find that reducing rpm to 2600 just after take off maybe a few hundred feet agl and 120mph and and sometimes in extreme heat, 26" at TPA keeps temps down.  But, my F has never had an issue of running hot.  

 

Edited April 12, 2016 by Browncbr1