one way valve

[avelciario]

I'll try to put an one way valve on the pipe from exhaust to fuel tank but its not a good idea, the engine becomes flooded. I'll try to look another one way valve that can be used in fuel lines and try to put in the pipe from tank to carb.

 

[ChasCS]

Question Mark

I'll try to put an one way valve on the pipe from exhaust to fuel tank but its not a good idea, the engine becomes flooded. I'll try to look another one way valve that can be used in fuel lines and try to put in the pipe from tank to carb.

Hi avelciario,
To what purpose?
Do you feel you will keep your fuel clean, or that this will give you some unknown advantage.
If this was something that was considered a positive move, others would have picked up on this, long before you thought of it.
It has no benefit, and as you have seen, it can't breathe correctly. I figure there must be a little give AND take. Equilibrium... Remember the Einstien theory of relativity, and "For every action, there is an equal and opposite reaction"?
You're essentially removing 1/2 of the variables... me thinks!!

If I'm mistaken/wrong, please take me out and shoot me.
Ah, but use that $1/2 Billion winning Power Ball as the projectile.
Take me out in a ball of glory!!

Chas

 

[lesclaypool]

I'm not sure what advantage this would have?

 

[avelciario]

I'll just to try if the pressure coming from the exhaust will not return to keep the fuel thank pressure steady, but its not a good idea it keeps on building more pressure, next step is to try to put in a fuel line this is not a filter its a oneway valve so its no relation on filtering the fuel to be clean. My next try is same way to keep the fuel line pressure even I shut down the engine for a short time.

---------- Post added at 12:16 AM ---------- Previous post was at 12:12 AM ----------

And I think it doesn't hurt me or my engine on trying something, maybe it works or not. And thanks for some inputs.

---------- Post added at 12:21 AM ---------- Previous post was at 12:16 AM ----------

And why wait for somebody to discover some advantage, when each one of us have a chance, explore what you love to do and enjoy, anyway its only a hobby and addiction... hehehehe... go guys.

 

[Greywolf74]

I'm all for personal exploration but i dont see what possible use this would be. Why do you want to try and keep you fuel tank and lines pressurized when the engine is off? Even if you could find a way for the pressure not to go backwards its just going to dump fuel into the carb after the engine is off and flood it. Or at least that is what I'm thinking anyway.

 

[2revo1maxx]

There is no advantage to this and it will flood your engine if it stalls.

 

[moe7404]

your fix is to get a tee fitting, put near the tank. put JB-weld on the out let hole, then drill a .030-.040, inch, in it. this causes the pressure in the tank to be smooth.

 

[2revo1maxx]

Why would you want to vent some of the pressure?

 

[hamz9561]

I guess to keep the exhaust pulses smooth. I thought about using a fuel filter inline to do the same thing.

 

[lesclaypool]

Why do we want to get the exhaust pulses smoother??

 

[Extreme RC Mods]

I wouldn't run anything "in-line" with the pressure line, there is minimal pressure and it's not hard to restrict the little bit that there is. A fuel filter will get soaked in oil and will restrict the pressure quite a bit.

 

[ChasCS]

Roll up your pant cuffs

Hi,
Each time the piston rises snd drops, that back pressure hose spurts just enough air into the gas tank for enough fuel to complete one piston rotation. The engine can only burn so much fuel per injection, & with that back pressure hose blocking its air flow in both directions, the pressure is too much, and therefore the engine gets just a little too much fuel and floods. As it was explained to me.

I know some folfks use as many as three gas line filters though, on the gasser/nitro helicopter kits. Better to be safe than sorry.

Chas

 

[lesclaypool]

Right, but those are on the fuel line, not the pressure line, correct? I know some folks run the coolers on the pressure line, but those are just a pretty much wide open heat exhchanger, nothing to do with pressure. Just cooling the exhaust gas pressure entering the tank.

 

[Extreme RC Mods]

The pressure line isn't really susceptible to the exhaust pulse, it works off of the exhaust pressure which is more of a constant pressure then a pulsing pressure. The way it works is at idle there will be a low amount of pressure in the tank, as the engine accelerates the pressure will build briefly but then it also tapers off as the rpm goes up. The idea behind the one way check valve is to maintain the highest pressure in the tank so the fuel supply to the needles is more constant making tuning more accurate. The downside to this is when the engine shuts off, the pressure continues to force fuel into the carb until the tank pressure is equal to the ambient air pressure and floods the engine. This will also happen when moving the RC from a cool environment to a warm one, the expanding air inside the tank will force fuel into the carb until things are equal but again, the engine will be flooded with fuel.

I have played around with many check valves and pumps in many different combinations. What I found was the small gains that were made, were heavily outweighed by the issues they created. jmo.

 

[ChasCS]

The pressure line isn't really susceptible to the exhaust pulse, it works off of the exhaust pressure which is more of a constant pressure then a pulsing pressure. The way it works is at idle there will be a low amount of pressure in the tank, as the engine accelerates the pressure will build briefly but then it also tapers off as the rpm goes up. The idea behind the one way check valve is to maintain the highest pressure in the tank so the fuel supply to the needles is more constant making tuning more accurate. The downside to this is when the engine shuts off, the pressure continues to force fuel into the carb until the tank pressure is equal to the ambient air pressure and floods the engine. This will also happen when moving the RC from a cool environment to a warm one, the expanding air inside the tank will force fuel into the carb until things are equal but again, the engine will be flooded with fuel.

I have played around with many check valves and pumps in many different combinations. What I found was the small gains that were made, were heavily outweighed by the issues they created. jmo.

Hi Extreme RC Mods,
And experience is the better part of valor!!
Thanks for sharing your wisdom.

Looking forward to some spring/summer bashing...

Chas

 

[hamz9561]

Thanks, Robin for clearing up the murk on the pressure pulses.

 

[Extreme RC Mods]

My pleasure buddy.

 

[2revo1maxx]

Drill a small hole in an air compressor tank. Fire up the compressor. by the time it reaches just a 2 or 3 psi you will hear nothing but constant air hissing out of the small hole......no pulsing. I know this from working with pumps and large boiler systems daily......and it also applies to RC nitro exhaust.