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  #1  
Old 07-06-2019, 08:58 AM
JDA_BTR JDA_BTR is offline
 
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Location: Baton Rouge, LA
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Default Optimum Engine Operating Procedures

So I've got this awesome RV-14, and it is running great. Do we know what the best operating procedures are for RPM/MP in various conditions?

I've been getting airborne, bringing the RPM back to 2500 and the MP to 26, then as I climb keeping the MP around 25. Don't know the best cruise settings at altitude yet going to run some test flights to find out.

A lot of us are flying this combination now. What are best practices anyone has learned from our setup here?
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  #2  
Old 07-06-2019, 09:30 AM
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DanH DanH is offline
 
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Ignition type and timing?
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  #3  
Old 07-07-2019, 08:03 AM
JDA_BTR JDA_BTR is offline
 
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Its an IO-390, setup with dual PMAGs. They are set for 29 Degrees shift, with a -7 initial, set at TDC.
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  #4  
Old 07-07-2019, 11:02 AM
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DanH DanH is offline
 
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Very good.

Quote:
I've been getting airborne, bringing the RPM back to 2500 and the MP to 26, then as I climb keeping the MP around 25.
Keep doing that, and lean in the climb to maintain target EGT. What is the target? Glance at your EGT shortly after liftoff, at WOT. Note the values, or even just one value. You'll see them drop when you make the first power reduction. Lean to put them back on the target.

Quote:
Don't know the best cruise settings at altitude yet going to run some test flights to find out.
Marvin McGraw has good cruise data running similar timing. Start here (there is a link to an earlier thread too):

http://www.vansairforce.com/communit...=171148&page=3
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  #5  
Old 07-07-2019, 12:52 PM
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M McGraw M McGraw is offline
 
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Location: Greenback, TN
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Default IO-390 RV-14

I have a very similar aircraft with about 300 hours on her. A standard IO-390 with Hartzell blended airfoil prop and the SDSEFI system. I run my ROP advance 23BTDC which is very close to where you have your PMags set.

My takeoff/climb procedure is very similar to yours in that I pull the prop to 2500RPM (only to make people on the ground happy, think about the noise). I only reduce throttle if I intend for a low level off altitude. I do use the target EGT method described by DanH above. I tend to cruise climb between 125 and 130KTs It has been a while since I calculated a Carson Speed, but I think it was in the 125Kt region.

I Believe you have another thread with performance data for 100ROP at various altitudes (I lost that thread). I tried to compare it to my aircraft, but most of my data is for higher altitudes than yours. I had trouble staying below the yellow arc on the airspeed at lower altitudes because I only record data at WOT. I have found I can get very consistent CHT and EGT (per cylinder) results at WOT, but partial throttle causes them to move around a bit. It may be a turbulence issue on the intake side.

I gave up on ROP cruise data fairly quickly. Basically 100ROP gained a few knots for a whole lot of fuel. I tend to run in accordance with the Lycoming recommended peak EGT or I run LOP and advance the ignition farther than 23BTDC. One thing I did learn during my testing is that the EFIS algorithms for finding peak EGT are great as a learning tool; however, I can get another 2 to 3 KTAS by adjusting the fuel flow VERY SLOWLY and finding peak manually. By slowly I mean give it a good 30 to 45 seconds between adjustments. I really need to go back to some old threads and rerun the data I published with manually adjusted EGT.

I have a chart with power/altitude/speed/fuel flow at home (I’m at work for a week). Will you be at Air Venture? I plan to be there all week.
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Last edited by M McGraw : 07-07-2019 at 03:09 PM.
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  #6  
Old 07-07-2019, 06:38 PM
JDA_BTR JDA_BTR is offline
 
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Iíll be rafting in Idaho but Iíll get to Oshkosh one year.

The slight speed diff for ROP isnít worth 2 GPH but Iíve collected some more data today to get that nailed down; my main goal is to identify optimum density altitude for cruise. The rest is for a big piece of graph paper and my further experimental education.
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  #7  
Old 07-07-2019, 07:20 PM
Bavafa Bavafa is offline
 
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I am probably running my engine a bit harder, I typically climb at 2600 RPM and WOP till I reach my desired altitude then back off to 2500 RPM unless I am doing some flight maneuvers or practicing instrument approach.
This weekend we had gone for a longer X-country trip to WY and the plane runs much nicer with a 10 degree advance at higher altitude (PMAG standard A curve). Our cruise altitude at 17500 yielded 164K @7.5G while at 12500, I was getting the same speed but 8.4G. This is with two person and 60-70LB of luggage +Oxygen. The overall burn rate (at higher altitude) was just shy of 8G an hour ramp to ramp.
Did I mention I love this plane.
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  #8  
Old 07-07-2019, 08:41 PM
JDA_BTR JDA_BTR is offline
 
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I would run it harder but I picked the Louisiana summer to break in my engine. The engine temps get hot in a hurry.
Mine is awesome too..... all I figured and some bonus too.
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