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What should the fuel pressure be for the engine driven pump?
- Thread starter Webb
- Start date
Looking at the TCDS for the Superior Vantage engine, it lists in Note 2:
Fuel Pressure Limits
Inlet to Pump, Min. -2 psig
Max. +35 psig
Lycoming TCDS has similar pressures with a higher maximum pressure at idle cut off and slight different max pressures for parallel vs serial boost pumps.
One thing I find interesting on the Vantage engine TCDS is the fuels that it is certified to operate on. One of the fuels is Motor Gasoline (R+M/2) (See Note 7) ASTM D4814, Min Octane 91 (no alcohol). This engine has the same bore, stroke and compression ratio as the Lycoming 360 that requires 100/100LL fuel.
Greg Arehart
Well Known Member
Webb,
FWIW, I have the same engine and boost pump. My fuel pressure normally runs about 9 psi. Limits are as Gary indicated. Not sure how one could really operate on -2 psi, but thats what the manual says.
greg
FWIW, I have the same engine and boost pump. My fuel pressure normally runs about 9 psi. Limits are as Gary indicated. Not sure how one could really operate on -2 psi, but thats what the manual says.
greg
Greg Arehart
Well Known Member
Mark,
The 9 psi is with the mechanical pump only. I'll have to look tomorrow and see how that changes with the boost pump on.
greg
The 9 psi is with the mechanical pump only. I'll have to look tomorrow and see how that changes with the boost pump on.
greg
I'm running 9
Gary - Thanks for the tech sheet. I printed it off so you helped me in more ways than this one. A negative 2 has to be a misprint.
Greg - I'm also running around 9 in normal flight.
I think I'll set my Dynon limits to 2 and 35 for the outside limits (in red). Now the question is to where to set the yellow warning limits. Not as concerned on the high end but when it comes to the low end, as a warning to turn the boost on. Maybe 6 - Hopefully one of those numbers that really never comes into question.
Gary - Thanks for the tech sheet. I printed it off so you helped me in more ways than this one. A negative 2 has to be a misprint.
Greg - I'm also running around 9 in normal flight.
I think I'll set my Dynon limits to 2 and 35 for the outside limits (in red). Now the question is to where to set the yellow warning limits. Not as concerned on the high end but when it comes to the low end, as a warning to turn the boost on. Maybe 6 - Hopefully one of those numbers that really never comes into question.
The -2 psi is the inlet to the engine driven pump. Not to be confused with a fuel pressure gauge reading AFTER the engine driven pump. With the electric boost pump off the engine driven pump pulls the fuel.
Consider different aircraft attitudes, acceleration states, plumbing, pulling the fuel through filters, a non operating electric pump, etc and you can see where you could end up with - psi to the engine driven pump inlet. By the way, low inlet pressure increases the chance of bubbles coming out of solution. Sometimes that can show up as fuel pressure fluctuations after the engine driven pump that go away when you turn on the electric boost pump; In which case you are on the ragged edge of vapor lock. Don't ask how I know that
Webb you seem to be mixing Carb numbers with FI numbers. The min 2 would more like a carb inlet number with a higher min for FI. If you are running at 9 all day you might want to know if anything changes; set it at 9 (or 8). Your transducer, plumbing, pumps, etc have given you a ref "normal" that's working for you. Give yourself the benefit of a first indication something is changing and tighten up the limits for your install.
Consider different aircraft attitudes, acceleration states, plumbing, pulling the fuel through filters, a non operating electric pump, etc and you can see where you could end up with - psi to the engine driven pump inlet. By the way, low inlet pressure increases the chance of bubbles coming out of solution. Sometimes that can show up as fuel pressure fluctuations after the engine driven pump that go away when you turn on the electric boost pump; In which case you are on the ragged edge of vapor lock. Don't ask how I know that
Webb you seem to be mixing Carb numbers with FI numbers. The min 2 would more like a carb inlet number with a higher min for FI. If you are running at 9 all day you might want to know if anything changes; set it at 9 (or 8). Your transducer, plumbing, pumps, etc have given you a ref "normal" that's working for you. Give yourself the benefit of a first indication something is changing and tighten up the limits for your install.
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Minimum fuel pressure at the servo is 14 psi and maximum is 45 psi, for a fuel injected Lycoming 180 HP engine. Normally should run 21-26 psi depending on the power setting. Weather it is a Superior or Lycoming engine shouldn?t make any difference with the spec.
Good Luck and Happy New Year,
Mahlon
?The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."
hevansrv7a
Well Known Member
Much different numbers
My Superior runs around 30 psi with only the engine driven, mechanical fuel pump operating, but that's pushing fuel into their standard FI setup. I am mystified that the same pump would produce only 9 psi. Are we looking at issues with instrument calibration? I don't see a big change with the boost pump on, either.
My Superior runs around 30 psi with only the engine driven, mechanical fuel pump operating, but that's pushing fuel into their standard FI setup. I am mystified that the same pump would produce only 9 psi. Are we looking at issues with instrument calibration? I don't see a big change with the boost pump on, either.
Sensor type
It could be the sensor type choosen for the monitor. I'm going to verify what I have programmed and you may want to do that also so we can compare notes later. If 2 of us are showing a 9 pounds, it's worth all of us verifying. Also, if memory serves, when the boost is on, it only goes up a few pounds.
I like the ideal of setting the warning (yellow section) high such as an 8 for an indication in drop sounds like a good ideal.
I'll report back when I get back from the hanger.
It could be the sensor type choosen for the monitor. I'm going to verify what I have programmed and you may want to do that also so we can compare notes later. If 2 of us are showing a 9 pounds, it's worth all of us verifying. Also, if memory serves, when the boost is on, it only goes up a few pounds.
I like the ideal of setting the warning (yellow section) high such as an 8 for an indication in drop sounds like a good ideal.
I'll report back when I get back from the hanger.
Greg, I looked at my logged flight data, and my fuel pressure is always in the 25-30 psi range whether the boost pump is on or off. It seems strange that our mechanical fuel pumps would differ so much in output pressure. I'll be interested to see if you show a significantly different pressure when your boost pump is on.
Mark
AZtailwind
Well Known Member
24-27PSI
Just as another data point- Flion's RV6A/superior-IO360/Blue Mnt/ is constantly reading in the mid to high 20's
Just as another data point- Flion's RV6A/superior-IO360/Blue Mnt/ is constantly reading in the mid to high 20's
Greg Arehart
Well Known Member
OK, just back from 2.4 more hours toward my required 40. Flying at altitudes from 5000 (Reno) to 1800 (Sac Valley) to 11000 (over Sierras). Fuel pressure ran about 9 psi with or without the boost pump on. Dropped to maybe 8.5 when I shoved the throttle forward but rapidly recovered to 9-9.3 (I have all this logged on the Dynon but haven't looked at the detailed log yet).
My suspicion is that there are different takeoff points. I am taking my pressure readings from a split just past the mechanical pump. Perhaps it would/should be higher (25-30) at the spider? I am far from a FI expert, this being my first experience with FI.
This is an interesting discussion...
greg
My suspicion is that there are different takeoff points. I am taking my pressure readings from a split just past the mechanical pump. Perhaps it would/should be higher (25-30) at the spider? I am far from a FI expert, this being my first experience with FI.
This is an interesting discussion...
greg
Check the sensor type in you Dynon
Greg - I had the wrong sensor type in the Dynon. Injected is a #2 type, carb is a #1. I too had about 9 psi showing.
When I changed it to the injected type (which I have), it ran about 25-26 psi which agrees with the other post. The boost pump runs it up about another 3 pounds.
Greg - I had the wrong sensor type in the Dynon. Injected is a #2 type, carb is a #1. I too had about 9 psi showing.
When I changed it to the injected type (which I have), it ran about 25-26 psi which agrees with the other post. The boost pump runs it up about another 3 pounds.
David-aviator
Well Known Member
Greg, probably you are running with a wrong sensor.
The mechanical pump puts out at least 20 psi and it is measured at the outlet of the pump. The pressure up at the spider (AFP system) is only about 1-3 psi.
My engine pump puts out 21 psi, the electric pump 29 psi.
Greg Arehart
Well Known Member
Thanks, I will check this tomorrow.
greg
greg
Greg Arehart
Well Known Member
Well, didn't get in the air yesterday, but today I reset the Dynon to sensor type 2 and got about 24 psi with the mechanical pump. Adding the boost pump brought the pressure up to about 30 psi. So, I guess that my setup is consistent with everyone else. Glad this came up and I got one more squawk corrected.
cheers,
greg
cheers,
greg
