E2510

I'm building an airplane that has the engine mounted on a pylon above the wing. The original design calls for a small tank mounted behind the engine in the pylon. I want a larger tank which means putting it down lower in the fuselage. Will the pressure port on the engine muffler be sufficient to keep fuel flowing up to the engine? This might be as much as 5 inches vertical. I wouldn't expect that the venturi would pull fuel that high.

DMcQuinn

My Feedback: (13)

you will not get very good engine running when the tank is 5 inches below the carb, even with muffler pressure. There is a device called a Cline regulator that is about $50 that works well. it uses crankcase pressure to pressurize the tank to about 5 or 10 psf. then there is a regulator right at the carburetor that drops the pressure back down to zero.
http://www.billsroom.com/pcfs/

Jetset

My Feedback: (2)

What about using a Perry Pump? Would that do it?
Myles

DMcQuinn

My Feedback: (13)

I haven't used a perry pump in many years, but I believe they are functionally equivalent to the Cline system mentioned previously. Years ago Perry sold a oscillating pump that worked off the natural vibration of the engine. It was bolted directly to the engine or firewall so that as the engine shakes, a cylinder inside the pump forces fuel thru it providing the pumping action. Other perry pumps use crankcase pressure differential.

Ted Farmin

I highly recommend the Cline reguator over a pump, voice of
expierience

Viper Pilot

Why not just place a one-way valve between the muffler and the fuel tank. I use one of these, and it triples the pressure. This probably would work in your situation.

VP

Ted Farmin

the muffler pressure isn't enough. The crankcase pulse pressure
when the piston gets to the bottom of its stroke will build up to
7lbs pressure of which the Cline system uses and puts it on top
of the fuel in your tank and then regulates it with a reguator
as close as you can mount it to the carburetor. It works get, I've
seen it work well on a Moki 1.8 and I've used it on my 1.08 and
.60 size engines. It is a system similar as the outboard motor
industry used to supply fuel to their engnes during the 1950s.

Ted Farmin

another problem if you put a check valve in the line from the
muffler is that the pressure (the small amount that it is) will
remain and cause to much pressure at idle and you won't be
able to adjust the idle mixture, believe me I've tried all these
things in the last 20 plus years.

E2510

Thanks to all of you for the input. It sounds lik the Cline regulator system is going to be the most reliable. It'll be a good exercize anyway, because if this airplane works out, I'm going to go with a .60 size next. This one calls for a size up to .29, but I'm going to use a .40 because of the altitude here.