"V" shaped mono tank?

[Terry Keeley]

My bud Olly asked this a while ago and at the time I thought it wouldn't work, looking at it again...

I want to make a tank to fit as low as possible in the bottom of my little 20 mono, the problem is where to put the pickup? Thinking of using 2 tied together, one in the bottom of the "V" for the straight, one in the back left as usual for the corners. I plan to use a hopper inside the main and am hoping it'll give a steady flow even if one of the main pickups is uncovered.

Anyone try this before? Any ideas if it'll work?

 

[Ron Olson]

Terry, I'm far from an expert but it seems like one pick-up line at the bottom of the tank should be fine.

 

[Sean Bowf]

I had asked this questions awhile back in the chat room. I have a larger mono, and have the plastic V-bottom 16 oz tank that is available. I was told to bring the pickup to the outside corner of the tank.

I was wondering because...if the boat lies on its side in the turns, it seemed like the bottom of the V would be best...but with the plastic tank, it actually wraps around the opening about an inch on both sides...

I have zero personal experience...so can only regurgitate what I heard...

Sean

 

[AndyBrown]

Terry,

It's easier to pull air through a tube than it is to pull fuel through a tube. With that in mind, Whacha think's gonna happen?!?!

Just build a fully sealed tank inside the tank. A two tank system! It won't matter where you place the small interenal tank, it will always be full until the main tank empties.

It's best to make the internal tank as tall as possible and not too wide. This will keep a tall colume of fuel that can't move away from the pick tube.

 

[Terry Keeley]

Thanks for the replys guys, and I'm sure you're right Andy, it'll suck air if one of the pick-ups is uncovered.

I'm going to use a sealed internal hopper tank, so if I put the main pickup in the bottom of the V, when it gets uncovered and air gets sucked into the hopper, does the air get displaced when there's fuel draw from the main pickup again?

Or...does the air pocket stay in the hopper until the main gets uncovered at the next corner, more air get sucked into the hopper etc. until its dry? Hmmmm....

ps: Sean you do want your p/u in the back left corner.

 

[Boris Mazor]

I did internal hope tank ~ 25 years ago. Internal tank should be placed on center of side main tank closest to carb. The size was 3/4x3/4" and 1.5-2' toll. It was not sealed! three- four 1/16 notches on the very bottom allows fuel run in to hope tank and 1/16 notch on the top will run out the air! When yours boat run straight, hope tank is full (up to level of fuel in main tank). When cornering the fuel slow drain out, but you still have enough to run before straight line. I can draw you picture. Boris

 

[Walt Barney]

Thanks for the replys guys, and I'm sure you're right Andy, it'll suck air if one of the pick-ups is uncovered.
I'm going to use a sealed internal hopper tank, so if I put the main pickup in the bottom of the V, when it gets uncovered and air gets sucked into the hopper, does the air get displaced when there's fuel draw from the main pickup again?

Or...does the air pocket stay in the hopper until the main gets uncovered at the next corner, more air get sucked into the hopper etc. until its dry? Hmmmm....

ps: Sean you do want your p/u in the back left corner.

Terry

The air in your hopper tank cannot excape and will get more air in every time the pick up tube has no fuel to pick up, causing bubbles to come to the carb via the fuel line, and then no more go fast. Maybe a large hopper tank could stop the air from the carb but with the way a mono runs in rough water, it may still get air to the carb.

Walr Barney

Tanks 2 U

 

[Terry Keeley]

Thanks guys, know what you mean Boris, made tanks like that for years, got the idea from Steve Ball who was the first to put the hopper inside the tank IIRC. Here's a pix of what I'm talking about: https://www.intlwaters.com/gallery/displayimage...707&pos=124

Except the bottom of the tank will be in a "V" shape and the pick-up in the bottom.

Thinking about it some more I'm sure you're right Walt, if it gets air in each corner the hopper will eventually empty and there will be bubbles to the carb.

Here's another angle. What if I had a small hole in the top of the hopper to release any trapped air, then if the main pickup was uncovered and air was sucked into the hopper it could be displaced the next time the main pulled in fuel.

Would that work to keep the hopper mostly full most of the time?

 

[tnrcboatracer]

Terry, If you vent the top of the hopper tank, there no longer is a pressure differential to push the fuel into the hopper tank from the main tank. The only way to give the hopper the ability to purge air is to add a vent line in the top with a check valve in it; and even then I'm not sure the air will ourge due to the low pressure differential. The check direction is set so that fuel can go out of the hopper, but air is prevented from going in. Does this make sense to you? The easiest way to minimize air to the carb from the hopper tank is to make it tall and narrow.

 

[AndyBrown]

Every time air is picked up by the main pick-up tube the air goes in the small tank. The internal tank will gradually get more and more air.

The reality is that by the time the small tank starts getting very much air the main tank is nearly empty and you should be finished with the race.

I've tried every kind of hopper configuration, but nothing beats the internal tank system.

Build the internal tank as tall as the main tank. It should be 15-20% of the main tank capacity.

You will drain both tanks dry and never know you were low on fuel until the engine flat runs out of fuel.

 

[Boris Mazor]

Thanks for the replys guys, and I'm sure you're right Andy, it'll suck air if one of the pick-ups is uncovered.
I'm going to use a sealed internal hopper tank, so if I put the main pickup in the bottom of the V, when it gets uncovered and air gets sucked into the hopper, does the air get displaced when there's fuel draw from the main pickup again?

Or...does the air pocket stay in the hopper until the main gets uncovered at the next corner, more air get sucked into the hopper etc. until its dry? Hmmmm....

ps: Sean you do want your p/u in the back left corner.

Terry

The air in your hopper tank cannot excape and will get more air in every time the pick up tube has no fuel to pick up, causing bubbles to come to the carb via the fuel line, and then no more go fast. Maybe a large hopper tank could stop the air from the carb but with the way a mono runs in rough water, it may still get air to the carb.

Walr Barney

Tanks 2 U

Hi, Walt! I talking about internal hope tank! Pressure in internal tank will not relate of number of holes, top hole or bottom hole das not meter - pressure in both tanks always the same!!!. Be careful! Boris

 

[Terry Keeley]

Terry, If you vent the top of the hopper tank, there no longer is a pressure differential to push the fuel into the hopper tank from the main tank. The only way to give the hopper the ability to purge air is to add a vent line in the top with a check valve in it; and even then I'm not sure the air will ourge due to the low pressure differential. The check direction is set so that fuel can go out of the hopper, but air is prevented from going in. Does this make sense to you? The easiest way to minimize air to the carb from the hopper tank is to make it tall and narrow.

Thanks for the reply Jon, yup, no way it's gonna draw fuel with a hole in the hopper! I think I know what you mean with the check valves but it sounds just a little too complicated...

 

[Terry Keeley]

Every time air is picked up by the main pick-up tube the air goes in the small tank. The internal tank will gradually get more and more air. The reality is that by the time the small tank starts getting very much air the main tank is nearly empty and you should be finished with the race.

I've tried every kind of hopper configuration, but nothing beats the internal tank system.

Build the internal tank as tall as the main tank. It should be 15-20% of the main tank capacity.

You will drain both tanks dry and never know you were low on fuel until the engine flat runs out of fuel.

Thanks for taking the time to put your mind to this Andy, I was leaning this way at one point. Million dollar question though is where to put the main pick-up, in the bottom of the "V" or in the back left corner... :blink:

 

[AndyBrown]

Every time air is picked up by the main pick-up tube the air goes in the small tank. The internal tank will gradually get more and more air. The reality is that by the time the small tank starts getting very much air the main tank is nearly empty and you should be finished with the race.

I've tried every kind of hopper configuration, but nothing beats the internal tank system.

Build the internal tank as tall as the main tank. It should be 15-20% of the main tank capacity.

You will drain both tanks dry and never know you were low on fuel until the engine flat runs out of fuel.

Thanks for taking the time to put your mind to this Andy, I was leaning this way at one point. Million dollar question though is where to put the main pick-up, in the bottom of the "V" or in the back left corner... :blink:

Put the main pick-up, in the bottom of the "V" .

 

[Terry Keeley]

Every time air is picked up by the main pick-up tube the air goes in the small tank. The internal tank will gradually get more and more air. The reality is that by the time the small tank starts getting very much air the main tank is nearly empty and you should be finished with the race.

I've tried every kind of hopper configuration, but nothing beats the internal tank system.

Build the internal tank as tall as the main tank. It should be 15-20% of the main tank capacity.

You will drain both tanks dry and never know you were low on fuel until the engine flat runs out of fuel.

Thanks for taking the time to put your mind to this Andy, I was leaning this way at one point. Million dollar question though is where to put the main pick-up, in the bottom of the "V" or in the back left corner... :blink:

Put the main pick-up, in the bottom of the "V" .

Ya, makes sense, thanks guys, great "think tank" here!!!

 

[moparbarn]

never tried one, so i can't say how well it might work, but what about a bladder style tank? a bladder inside a hard tank? pressurize the tank as usual, except it squeezes on the outside of the bladder. pickup inside the bladder - no air or pickup issues. a lot of airplane guys use hard tanks with bladders inside for aerobatics. they claim they're the shizit for fuel feed issues. just a thought.........

 

[RCUK John]

I want to make a tank to fit as low as possible in the bottom of my little 20 mono, the problem is where to put the pickup? Thinking of using 2 tied together, one in the bottom of the "V" for the straight, one in the back left as usual for the corners. I plan to use a hopper inside the main and am hoping it'll give a steady flow even if one of the main pickups is uncovered.
Anyone try this before? Any ideas if it'll work?

Any interest to you? FSRV race standard Tanks and Headers

http://www.iansboats.co.uk/

http://www.prestwich.ndirect.co.uk/fueltanks.htm

(If the links don't work then copy and paste them)

 

[Terry Keeley]

never tried one, so i can't say how well it might work, but what about a bladder style tank? a bladder inside a hard tank? pressurize the tank as usual, except it squeezes on the outside of the bladder. pickup inside the bladder - no air or pickup issues. a lot of airplane guys use hard tanks with bladders inside for aerobatics. they claim they're the shizit for fuel feed issues. just a thought.........

That'd prolly work too but again is more complex than I want, thanks!

 

[Terry Keeley]

I want to make a tank to fit as low as possible in the bottom of my little 20 mono, the problem is where to put the pickup? Thinking of using 2 tied together, one in the bottom of the "V" for the straight, one in the back left as usual for the corners. I plan to use a hopper inside the main and am hoping it'll give a steady flow even if one of the main pickups is uncovered.
Anyone try this before? Any ideas if it'll work?

Any interest to you? FSRV race standard Tanks and Headers

<a href="http://www.iansboats.co.uk/" target="_blank">http://www.iansboats.co.uk/</a>

<a href="http://www.prestwich.ndirect.co.uk/fueltanks.htm" target="_blank">http://www.prestwich.ndirect.co.uk/fueltanks.htm</a>

(If the links don't work then copy and paste them)

Thanks for that, guess the FSR guys don't worry about getting fuel from V tanks so either should I! :lol:

Wow, some of those tanks hold almost a US gallon! :blink:

Guess the "float chamber" does the same as our hopper tanks...

 

[AndyBrown]

I want to make a tank to fit as low as possible in the bottom of my little 20 mono, the problem is where to put the pickup? Thinking of using 2 tied together, one in the bottom of the "V" for the straight, one in the back left as usual for the corners. I plan to use a hopper inside the main and am hoping it'll give a steady flow even if one of the main pickups is uncovered.
Anyone try this before? Any ideas if it'll work?

Any interest to you? FSRV race standard Tanks and Headers

<a href="http://www.iansboats.co.uk/" target="_blank">http://www.iansboats.co.uk/</a>

<a href="http://www.prestwich.ndirect.co.uk/fueltanks.htm" target="_blank">http://www.prestwich.ndirect.co.uk/fueltanks.htm</a>

(If the links don't work then copy and paste them)

Thanks for that, guess the FSR guys don't worry about getting fuel from V tanks so either should I! :lol:

Wow, some of those tanks hold almost a US gallon! :blink:

Guess the "float chamber" does the same as our hopper tanks...

"Guess the "float chamber" does the same as our hopper tanks..."

Terry,

The "float chamber" they use in FSV-Vee maintains a constant head pressure. However this fuel supply is not pressurized. They use pipe pressure to force fuel to the float chamber but the fuel in the chamber is not pressurized.

This system works exactly the same as the float bowl is a standard automotive carburator. The fuel is under the force of gravity only.

Hopper tanks and "tank in a tank" systems are under the full influcence of gravitational head pressure, meaning as they empty they supply less pressure, meaning the engine runs leaner as the tank empties.

A "Uniflow system" will provide constant head pressure and they work great. I have used them in boats in the past, but they require special care in using them.