ORIGINAL: 790
Has anyone tested the Webra fuel pressure regulator? It uses a slightly different approach by pressurizing the fuel tank via the case then regulates that supply by muffler pressure to match engine speed. Sounds good and doesn't mention a need for a special carb.
[link=http://www.webra-austria.at/motor.php?folder=ACCESSORIES&lang=EN]http://www.webra-austria.at/motor.php?folder=ACCESSORIES&lang=EN[/link]
790,
The Webra fuel pressure regulator.
I did not try the Webra regulator but read the description and for me they are nearly all the same so I give you my two cents!
Webra let you connect the reference input for the controller with the connection of the muffler.
Background of the principle is:
During flight the regulator will control the fuel pressure to the spray bar of the carburetor equal to the pressure of the reference input of the controller, so in this case the exhaust pressure.
This way of connection the result is, the carburetor is feed with the same pressure as normal when the exhaust connection is connected with the air input of the tank.
Your profit is, the position of the plane doesn’t any matter, the ratio of fuel and air is like horizontal flight with “no regulator” and the standard carburetor.
Some points to think about:
First, mount the controller as close as possible near the carburetor, see the picture for example.
Second point is, the exhaust pressure is pulsating, when you cannot adjust the fuel air ratio adequate you maybe can put a restrictor (and capacitor) in the line between the muffler and the reference connection of the regulator. Normally the tank pressure is an evenly average pressure of the exhaust pulsating pressure.
Third point is, be aware of the tank pressure when used a crankcase tap, it can rise to 5 -7 PSI, enough to pres the fuel 20 – 30 feet above the plane!. Think about where we can find the hydrocarbon liquid when something goes wrong in the plane!!!! ( google for “Koseq”)
No engine pressure tap?
Because we normally do not need such a high tank pressure when the tank is mounted behind the firewall, I use the exhaust connection and a check valve to pressurize the tank , see the picture.
The reference connection of my controllers/regulators I connect with the brass tube in same position as the air intake of the carburetor, this way I realize compensation of any (airspeed!) pressure near the air intake also when the engine is mounted inside a hatch.
Keep in mind, the Webra regulator you probably also can use the way I do, see the blue and orange arrows.
If there are more questions I maybe can answer, please ask.
Success.
Cees