Christer
Well Known Member
Here is a puzzling question? I have a new 0-360 engine with a MA4-5 carb. I have a Garmin G3X system that records every imaginable parameter once per second.
On my initial phase 1 test flights, I had the following performance indications:
TAS 170 kts, MAP- 23.5, RPM 2410, density alt 3047, OAT 12 deg C.
I had an issue with the carburetor and it was exchanged for a new one of the same exact P/N (5-4164-1). After installation here are my performance numbers:
TAS 165 kts, MAP-23.6, RPM 2390, density alt 2914, OAT 10 deg C
Somewhere I lost 5 kts. Fuel load was very close to the same so aircraft weight was the same. Both flights were at full rich due to new engine still. The engine seems to be producing less power only by the numbers, it runs and feels the same.
There is one foot note to add. During the carb change I noticed that the hole in the Van's throttle cable bracket that sits between the carb and the sump was slightly smaller in diameter than the sump opening by about 1/8 in. I opened it up to match the sump which should have improved performance if anything.
Any good thoughts on where the 5 kts of airspeed went?
On my initial phase 1 test flights, I had the following performance indications:
TAS 170 kts, MAP- 23.5, RPM 2410, density alt 3047, OAT 12 deg C.
I had an issue with the carburetor and it was exchanged for a new one of the same exact P/N (5-4164-1). After installation here are my performance numbers:
TAS 165 kts, MAP-23.6, RPM 2390, density alt 2914, OAT 10 deg C
Somewhere I lost 5 kts. Fuel load was very close to the same so aircraft weight was the same. Both flights were at full rich due to new engine still. The engine seems to be producing less power only by the numbers, it runs and feels the same.
There is one foot note to add. During the carb change I noticed that the hole in the Van's throttle cable bracket that sits between the carb and the sump was slightly smaller in diameter than the sump opening by about 1/8 in. I opened it up to match the sump which should have improved performance if anything.
Any good thoughts on where the 5 kts of airspeed went?