I decided to bite the bullet and try out LOP.
First thing I did was started reading how to go about doing it properly so I wouldn't cook my engine.
Next, I ran fuel flow tests to determine the flow rate at peak. Then contacted Don at Airflow performance and he looked at my data and graphs and sent me a restrictor for cylinder #4. I re-ran the data and then decided to adjust 1 more restrictor (cyl #3). Peak is now about 0.1 gal/hr spread at 8,500 feet.
Here are the numbers at 8,500 feet I now have.
I just took a trip and ran 50 LOP out at 9,000 feet. The flight went from Fairhope, AL to Naples, FL and flight time was 3.2 hours with total fuel burn was 25.2 gallons. Although I didn't write this down, it seems like the numbers for travel were - outside temp 37F, MP 21.7, and RPM 2250.
Once I had climbed to altitude, I went through the quick pull to the approximate temp and them tweaked it until I got the temp reading I was looking for.
Clinder head temps dropped. I didn't write them down but they were in the 340's and about 10 degrees cooler than 100 ROP.
Flow rate went from 10 gal/hr to 7.2 gal/hr.
TAS dropped from 163 to 158 knots.
My impression..........
The engine ran cooler - lower cylinder temps mean longer life
Endurance (taking reserves into account) went from approximately 3 hours to approximately 5 hours.
Range, increased from 550 miles to 900 miles.
Fuel burn was 28% better.
Speed decrease by approximatey 3%.
I also noticed that as you enrichen to just past 50 LOP the engine starts a nice pick up in power - somewhere around 45 LOP. I'ld call this the sweet spot and this is what I shot for on the trip to Key West we took, and the way back.
Is it worth it? Definately. To loose 3% speed and get 28% better fuel economy...not to mention a cooler running engine.
First thing I did was started reading how to go about doing it properly so I wouldn't cook my engine.
Next, I ran fuel flow tests to determine the flow rate at peak. Then contacted Don at Airflow performance and he looked at my data and graphs and sent me a restrictor for cylinder #4. I re-ran the data and then decided to adjust 1 more restrictor (cyl #3). Peak is now about 0.1 gal/hr spread at 8,500 feet.
Here are the numbers at 8,500 feet I now have.
I just took a trip and ran 50 LOP out at 9,000 feet. The flight went from Fairhope, AL to Naples, FL and flight time was 3.2 hours with total fuel burn was 25.2 gallons. Although I didn't write this down, it seems like the numbers for travel were - outside temp 37F, MP 21.7, and RPM 2250.
Once I had climbed to altitude, I went through the quick pull to the approximate temp and them tweaked it until I got the temp reading I was looking for.
Clinder head temps dropped. I didn't write them down but they were in the 340's and about 10 degrees cooler than 100 ROP.
Flow rate went from 10 gal/hr to 7.2 gal/hr.
TAS dropped from 163 to 158 knots.
My impression..........
The engine ran cooler - lower cylinder temps mean longer life
Endurance (taking reserves into account) went from approximately 3 hours to approximately 5 hours.
Range, increased from 550 miles to 900 miles.
Fuel burn was 28% better.
Speed decrease by approximatey 3%.
I also noticed that as you enrichen to just past 50 LOP the engine starts a nice pick up in power - somewhere around 45 LOP. I'ld call this the sweet spot and this is what I shot for on the trip to Key West we took, and the way back.
Is it worth it? Definately. To loose 3% speed and get 28% better fuel economy...not to mention a cooler running engine.
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