|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
08-15-2020, 07:22 PM | #1 |
Senior Member
Join Date: Jul 2019
Location: Oklahoma City, OK
Posts: 184
|
Fuel pressure at the carburetor?
For you math nuts. What is the fuel pressure at the carburetor fuel inlet when the tank has 10 gallons of fuel, and fuel shut-off in the cab is wide open?
__________________
Not a Purist. |
08-15-2020, 07:53 PM | #2 |
Member
Join Date: May 2010
Location: Chief lake BC Canada
Posts: 60
|
Re: Fuel pressure at the carburetor?
Nominal
|
Sponsored Links (Register now to hide all advertisements) |
|
08-15-2020, 07:57 PM | #3 |
BANNED
Join Date: Dec 2019
Posts: 1,196
|
Re: Fuel pressure at the carburetor?
30/31 has more than a 28/29,..over 2psi on a full tank,it will run a Stromberg 97 no problem
|
08-15-2020, 08:10 PM | #4 |
Senior Member
Join Date: Mar 2017
Location: southern California
Posts: 725
|
Re: Fuel pressure at the carburetor?
The specific gravity of car fuel at 60F is about 0.73 (Google).
The vertical distance from the carb inlet to the top of a late 1930 full tank is about 22 inches. If the liquid was water, then the pressure would be 22 in/H2O. But this is fuel, so 22 x .73 = 16.06 in/H2O 16.06 = 0.58 PSI. What do you guys think? Sound about right? Revised 8-16-2020. Was 60C, is 60F. Last edited by 1930-Pickup; 08-16-2020 at 06:36 PM. |
08-15-2020, 10:47 PM | #5 | |
Senior Member
Join Date: Jul 2016
Location: Orangeville Illinois
Posts: 461
|
Re: Fuel pressure at the carburetor?
Quote:
|
|
08-16-2020, 02:29 AM | #6 | |
Senior Member
Join Date: Jul 2010
Location: United Kingdom
Posts: 1,441
|
Re: Fuel pressure at the carburetor?
Sponsored Links (Register now to hide all advertisements)
Quote:
|
|
08-16-2020, 04:58 AM | #7 |
Senior Member
Join Date: Jul 2018
Location: Dallas, TX, Angola, IN
Posts: 157
|
Re: Fuel pressure at the carburetor?
Correct. About half a pound of pressure.
|
08-16-2020, 05:25 AM | #8 |
Senior Member
Join Date: Sep 2019
Location: Fort Gratiot, Michigan
Posts: 2,296
|
Re: Fuel pressure at the carburetor?
please tell us why it matters!
|
08-16-2020, 05:54 AM | #9 |
Senior Member
Join Date: Jul 2010
Location: United Kingdom
Posts: 1,441
|
Re: Fuel pressure at the carburetor?
Well, it could matter if one decided to put a fuel tank at the back of the car and utilise a pump. (It is also a neat math exercise.)
Last edited by johnbuckley; 08-16-2020 at 06:59 AM. |
08-16-2020, 06:59 AM | #10 |
Senior Member
Join Date: Jan 2016
Posts: 2,096
|
Re: Fuel pressure at the carburetor?
Oh you guys are killing me. My head hurts. I'm confused. I'm old. What math, arithmetic pleeeeeze save me.
All I know and care about is when I turn the valve the gas flows down hill. That has something to do with gravity, and that is good enough for me thank you. |
08-16-2020, 07:57 AM | #11 |
Senior Member
Join Date: Apr 2015
Location: Saint Cloud Mn
Posts: 745
|
Re: Fuel pressure at the carburetor?
This is called “head pressure”. For those that fly this is important especially between high wing and low wing aircraft.
|
08-16-2020, 09:11 AM | #12 |
Senior Member
Join Date: Jul 2019
Location: Oklahoma City, OK
Posts: 184
|
Re: Fuel pressure at the carburetor?
Thats funny. Two carburators and multiple shut-off valve changes and still if I don't take special steps fuel will drip from the intake. Having had to drain the tank multiple times over the past year, I was surprised how little pressure there was at the fuel line on a full tank. I figure more than 60 lbs of fuel. Thought it would be an interesting question.
__________________
Not a Purist. |
08-16-2020, 09:28 AM | #13 |
Senior Member
Join Date: Sep 2019
Location: Fort Gratiot, Michigan
Posts: 2,296
|
Re: Fuel pressure at the carburetor?
A wise man indeed. Your logic is what the hobby is all about. Our hobby will last forever with people like you. Hooray !
|
08-16-2020, 09:31 AM | #14 |
Senior Member
Join Date: May 2010
Location: Long Island, NY
Posts: 3,463
|
Re: Fuel pressure at the carburetor?
The equation for the static pressure at the bottom of the tank Pressure = density of gasoline x acceleration due to gravity x height of tank. This is high school science and it came before rocket science! As a matter of fact, Daniel Bernoulli (1700 to 1782), a Swiss mathematician and physicist, developed this science in his theories of fluid mechanics.
__________________
Bob Bidonde |
08-16-2020, 10:07 AM | #15 |
Senior Member
Join Date: Jun 2015
Location: Red Deer, Alberta
Posts: 5,043
|
Re: Fuel pressure at the carburetor?
The specific gravity of car fuel at 60C is about 0.73 (Google).
Methinks that you meant 60°F
__________________
If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn! |
08-16-2020, 11:59 AM | #16 | |
Senior Member
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
|
Re: Fuel pressure at the carburetor?
Quote:
??????? I've been a CFII/MEII for 40 years. Your gonna have to explain that one to me. Last edited by Patrick L.; 08-16-2020 at 12:12 PM. |
|
08-16-2020, 12:48 PM | #17 |
Senior Member
Join Date: Aug 2011
Location: Eagle Bend, MN
Posts: 2,025
|
Re: Fuel pressure at the carburetor?
It's not about the weight of the volume of the tank, it's about the weight of the column of fuel. A water tower with water level at 100 feet will have the same pressure if it hold 100 gallons or 1 million gallons.
__________________
"There are some that can destroy an anvil with a teaspoon and shouldn't be allowed to touch anything resembling a tool." |
08-16-2020, 01:12 PM | #18 | |
Senior Member
Join Date: Aug 2018
Posts: 2,332
|
Re: Fuel pressure at the carburetor?
Quote:
My brain hurts, but then I could not get through/pass Physics class in College either. |
|
08-16-2020, 05:41 PM | #19 |
Senior Member
Join Date: Jul 2012
Location: Central Maine
Posts: 644
|
Re: Fuel pressure at the carburetor?
The pressure a liquid exerts depends on the height/depth of the liquid, its weight density and force of gravity.
Two equations: P = mgh or P = Dw(h) where m = liquid mass, g = gravity, h = liquid height/depth and Dw = liquid weight density. Either way you do it the answer here, ( 22" height ) = .58 lbs/sq inch. What no one figured tho' is the # of sq inches of area in the cross section of the tube that feeds the gas to the carburetor. It certainly is not 1 sq inch. The ID of the tube might be 1/8" or .125 ". Some of you are asleep now with these #'s. If not you can continue on. It is an interesting exercise. The only answer needed here is that the system in a Model A works so the Ford engineers had it figured out OK. Bill |
08-16-2020, 05:53 PM | #20 |
Senior Member
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
|
Re: Fuel pressure at the carburetor?
If I wanted to know the pressure [ I don't ] I would just hook up a gauge. Maybe the needle would give a little wiggle.
|
|
|
Sponsored Links (Register now to hide all advertisements) |
|