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1. 10:40 AM - Re: Automotive man goes AIR Motive (Brinker)
2. 01:09 PM - Re: Automotive man goes AIR Motive (FLYaDIVE@aol.com)
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Subject: | Re: Automotive man goes AIR Motive |
--> AnPMech-List message posted by: "Brinker" <brinker@cox-internet.com>
I was told that on the IO540 or any other Lycoming fuel injected
engine that they required only 4-5 psi to operate the injection system. And
that that was what the mechanical fuel pump was rated at. Which was
astonishing to me since I only have experience with automobile type
injection systems that normally have 40 psi plus to operate. Is the 4-5 psi
correct ? If so with lets say 40 gallons of fuel in each tank I would think
that gravity would supply at least close to this type pressure out of a 3/8
line. Although I have not done a test to show this. I believe I will though
at a future date just to satisfy my curiosity.
I have a 94 model Chevy pickup that we recently changed the
throttle body design 350 engine over to a multi port fuel injected LT1
engine. We did change the fuel pump to the proper pump for that engine
during installation. Was told the proper pump needed to put out 50-60 psi
for the LT1. We still have not gotten the bugs out of the system yet to get
the engine to run consistently. We have changed several sensors that we're
suspect and still it was not running consistent. Finally we did a fuel
pressure check to discover the new fuel pump was weak and only producing
around 7-9 psi. Have yet to change pump since it is a bear to replace since
it is in the fuel tank. I am still driving the truck I just cannot use full
throttle or at times (not all the time) will act as though the fuel shut off
and it fall's on it's face. What I am getting at is that the pump is putting
out anywhere from at least 40-50 psi less than the required pressure but the
vehicle is still drivable and has sufficient power for normal driving. To me
this is very interesting and indicates that "perhaps" all FI engines will
operate on lower than published pressures. If this is true and the Lycoming
only needs 4-5 psi to operate nomally (which I still have'nt verified) then
the IO540 "should" run on much less than the 4-5 psi. Which would not be
much.
I will still install the boost "safety" pump on my Comp 6 just for
peace of mind and for quicker easier starting purposes.
Does anyone out there have the psi spec's on a IO540 or other FI
aviation engines ?
Thanks Randy
----- Original Message -----
From: "Marvin Dupree" <97corvette@cox.net>
Subject: Re: AnPMech-List: Automotive man goes AIR Motive
> --> AnPMech-List message posted by: Marvin Dupree <97corvette@cox.net>
>
> the wings would have to be very high to provide the pressure required
> for fuel injection. hence the boast pump.
> marvin m20e
> On Dec 16, 2005, at 8:38 PM, FLYaDIVE@aol.com wrote:
>
>> --> AnPMech-List message posted by: FLYaDIVE@aol.com
>>
>> In a message dated 12/16/05 1:31:24 PM Eastern Standard Time,
>> brinker@cox-internet.com writes:
>>
>>> Maybe Cessna is confident enough to not have boost pumps on their
>>> high wing planes
>> ==================
>> I don't know about ALL Cessnas, but the C-177 Cardinal has a boost
>> pump and
>> it is a high-wing
>>
>> Barry
>> "Chop'd Liver"
>>
>>
>
>
>
Message 2
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Subject: | Re: Automotive man goes AIR Motive |
--> AnPMech-List message posted by: FLYaDIVE@aol.com
Randy:
I have enclosed my responce within the body of your eaml. Please read on.
Barry
=================================
In a message dated 12/17/2005 1:41:44 PM Eastern Standard Time,
brinker@cox-internet.com writes:
I was told that on the IO540 or any other Lycoming fuel injected
engine that they required only 4-5 psi to operate the injection system. And
that that was what the mechanical fuel pump was rated at. Which was
astonishing to me since I only have experience with automobile type
injection systems that normally have 40 psi plus to operate. Is the 4-5 psi
correct ?
-------------------------------
I must plead ignorance of the automotive fuel injected system. But my
question would be is that Supply Fuel pressure form the fuel tank or INJECTION
PRESSURE? I know diesel systems use about 1000 to 3000 PSI for their fuel injection
system.
==================================================
If so with lets say 40 gallons of fuel in each tank I would think
that gravity would supply at least close to this type pressure out of a 3/8
line. Although I have not done a test to show this. I believe I will though
at a future date just to satisfy my curiosity.
Gravity pressure is VERY nil. Here are some numbers to use:
A column of water 1 FOOT (12") of high will develope 0.432 PSI at sea level.
Take the height of the gas in the wing at the wing height and SUBTRACT the
Height of the Fuel Bowl above ground, and that will give you the potential
height.
Now multiple that by 0.432 and that is how many PSI of fuel pressure you will
develop.
Well, not really .... REMEMBER FUEL weights less than water. Water = 8
Lbs/Gal and Fuel = 6 Lbs / Gal.
If you want to you can work out a ratio.
=======================================================
I have a 94 model Chevy pickup that we recently changed the
throttle body design 350 engine over to a multi port fuel injected LT1
engine. We did change the fuel pump to the proper pump for that engine
during installation. Was told the proper pump needed to put out 50-60 psi
for the LT1. We still have not gotten the bugs out of the system yet to get
the engine to run consistently. We have changed several sensors that we're
suspect and still it was not running consistent. Finally we did a fuel
pressure check to discover the new fuel pump was weak and only producing
around 7-9 psi. Have yet to change pump since it is a bear to replace since
it is in the fuel tank. I am still driving the truck I just cannot use full
throttle or at times (not all the time) will act as though the fuel shut off
and it fall's on it's face. What I am getting at is that the pump is putting
out anywhere from at least 40-50 psi less than the required pressure but the
vehicle is still drivable and has sufficient power for normal driving. To me
this is very interesting and indicates that "perhaps" all FI engines will
operate on lower than published pressures. If this is true and the Lycoming
only needs 4-5 psi to operate nomally (which I still have'nt verified) then
the IO540 "should" run on much less than the 4-5 psi. Which would not be
much.
Randy, there is something else that you MUST consider. VOLUME OF FLOW!
What size fuel lines are in the car? I'd bet dollars to donuts that they are
NOT 3/8". I'd bet that they are 1/3 that diameter ... 1/8" Diameter. So you
would think that a 1/8" fuel line would require MORE pressure ... WRONG!
Why? Because the fuel flow requirements in a car is in direct proportion to HP.
YES, some cars have TWICE the HP of our planes BUT! They do not run at 65 -
75 and 100% of their HP as a plane does. A car cruising at say 75 MPH will use
only about 20 HP in flat road cruse.
I use to race a Buick Skylark Custom, it had a 350 CID engine. I wanted more
HP so I went to Dual 650 Holly's. I LOST POWER and sometimes stumbled. Why?
Because the Dual 650 Holly's required MORE air flow and MORE FUEL ... I had
to install a fuel pump back at the gas tank. That may be the problem you are
having with your pickup.
========================================
I will still install the boost "safety" pump on my Comp 6 just for
peace of mind and for quicker easier starting purposes.
Does anyone out there have the psi spec's on a IO540 or other FI
aviation engines ?
If you are serious about this engine I would get the Maintenance and Parts
Manual from Lycomming. I'm sure this information would be in there.
Barry
"Chop'd Liver"
==========================================
Thanks Randy
Barry
"Chop'd Liver"
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