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Pressurized fuel system

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Ghost0

Guest
I was wondering if anyone has tried to pressurize their fuel system? This is something we typically do on 2 stroke R/C engines. It it set up by putting a fitting on your tank and exhaust and running some fuel line between them. The effect is using some exhaust pressure to lightly pressurizing the tank making more fuel flow possible.
 


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jpilot

Guest
These little engines can get way more fuel than they can use with just gravity feed. Why complicate things? I don't think I want exhaust gunk (and maybe sparks) spewing into my fuel tank.

It is a simple and light solution in R/C planes because they need some type of fuel pump. A pressurized tank with a flop tube assures a supply of fuel regardless of the attitude of the airplane.

If you need a fuel pump on a small two stroke, an impulse driven diaphram pump like the ones that are commonly used on ultralights is a good solution.
 
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Ghost0

Guest
I was just wondering. I was reading about boost bottles and it seems this would accomplish almost the same thing.
 
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andyinchville1

Guest
Boost bottles don't actually pressurize the fuel system they act as an accumulator and prevent the reversion pulse from interfering with the new intake charge.....I did think about the RC engine idea of pressurizing the fuel system BUT i think the big difference is that
RC engines don't (at least the small glo ones) don't have carbs with floats in them to hold a reserve of fuel so I think they use pressure to help ensure a steady flow of fuel to the carb...any RC people out there?

Andrew
 
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djase10

Guest
Hi All.

Its an old thread , but I'm re-hashing..

I think it would be of benefit for the fuel tank to be pressurized.
Like over sized injectors & MASSIVE fuel pressures in turbo cars.

The fuel would be better ATOMIZED via pressure
than the tiny trickle that a STOCK system provides Via gravity..

I'm not thinking exhaust though,,
I think a tyre valve fitted to the fuel tank, and air pumped in by a bike pump.

As long as the tank is under pressure , and NO VACUUM occurs , all would be sweet .

Any one tried it on a HT????
Cheers
Jase
 
Joined
Jun 3, 2008
Messages
59
Fuel pressure on a EFI car is a differant story, as mentioned above carbs have a float bowl, the only thing you will gain presurising the tank is blowing the needle out of the seat and flooding the float bowl.
 

Mountainman

Active Member
Joined
Jun 15, 2008
Messages
3,579
just a simple thought to remember

these engines have been engineered to THE FINEST point possible

they are not in any way -- lacking in the gas dept

ride that MB thing
 
Last edited:

kawasaki999

Member
Joined
Jan 18, 2008
Messages
335
On a Tanaka site I read that they want the tank to be slightly pressurized, its around 2 lbs. This is done by the gas cap, it has a check valve built in the cap, lets air in, but wont let it out. Tanaka says to check pressure in tank, shake tank a little, let it set a minute, pull off the fuel line to carb while pinching the line and hold line above the tank, fuel should flow out, or loosen the cap and listen for a hiss. Tanaka says the engine will still run ok with out pressure but top end will suffer. So when I made my 1 gal tanks for my gp 460,s I went to the local lawn mower shop and picked up check valves and 2 hole fuel gromets,3 hole gromet if you use a primer bulb from any echo weed wacker and installed them In my cheap 2.66 gas tank. My top speed dont suffer!
 

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djase10

Guest
Thats interesting K999..

My engine IS starving for fuel at the moment, thats why im thinking "pressurized" thoughts.

My bike has developed a vibration that is stopping the fuel getting to the carb.

I hold the fuel line and presto, let go and it bogs down =@38kmh exactly..

Strangely, this vibration is since i replaced the rubber in the frame mounts , so i'll have to get rid of the rubber .

Just over tightened the mount, and broke it , so taking the motor off again to fabricate some new ones -without the rubber..

Pressurized tank still in my minds eye though.

Also, 2 mid eighties turbo cars ( Nissan EXA & Turbo Daihatsu charade) used forced induction "thru the carby" , so i reckon it wouldnt hurt to try it.

Jase
 
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