mhbirdfd

Inverted Fuel Tank
I have an inverted super tigre 3000 engine on my Hanger 9 - P-51 1.50 (80" wingspan) and when I installed the fuel tank I put it in upside down by accident because all the work you do on the airplane is from the bottom after you take off the wing, I start the engine with the plane inverted so the engine is right side up, it runs good, starts easy, I flip it over while its running and tested the engine and it runs fine, a little sluggish on low idle, does anyone know if its ok to leave the fuel tank essentially upside down, the pressure line would be at the bottom under fuel ????

BuschBarber

My Feedback: (2)

The purpose of the Overflow, in a fuel tank, is to allow air to replace the space that the fuel used to occupy when it was in the tank. If you connect this line to the muffler, it helps pressurize the tank and improve the idle.

It should work either way.

jerdavis

My Feedback: (3)

One problem you will have is after running at power and pressurizing the tank, when you throttle back the tank will vent raw fuel into the muffler. This can flood and kill the engine. It will also give you poor fuel economy since fuel will be going out the tail pipe every time you throttle back.

JD

DMcQuinn

My Feedback: (13)

Also, you will have to fill the tank with the plane inverted. If you try to pump fuel in when upright, it will be immediately forced back out the vent line. But it should work.

mhbirdfd

JD, thanks...you are right when I throttle back from full to idle (too fast) it stalls the engine 70% of the time, I think I will be flipping the tank. Thanks Dennis

mhbirdfd

The odd thing is that I will have to fuel it with the plane right side up and then flip it over to start it. Then flip it back to fly. I heard you cant start a glow engine when its upside down, is this true ?

freeair

a glow engine will start and run in any position. thers no need to flip over a large 80 inch span model for starting, normally when you have to do this its more your fuel tank is not inline with the engines venturi and the engine wants to flood.

BuschBarber

My Feedback: (2)

I have not had a problem with Inverted gasoline engines, but some Glow engines have been more difficult to start when Inverted, I think the tank is part of the problem, but fuel pools in the Glow Plug recess and floods the engine. You need a Hot igniter and sometimes it is necessary to flip the plane over.

Some 4 stroke guys mount the engine 10 deg off verticle, to help prevent this problem.