It's from Kinsler. Not sure the part number, Earl spec'd it for me when we were designing the system.
Yes, I will still have to watch the fuel level in each tank. But why is that harder than watching the level in one tank?
8 stacks with two tanks
- Thread starter LloydGT40
- Start date
It's from Kinsler. Not sure the part number, Earl spec'd it for me when we were designing the system.
Yes, I will still have to watch the fuel level in each tank. But why is that harder than watching the level in one tank?
Seymour Snerd
Lifetime Supporter
You mean, when did I stop beating my wife? :laugh:
First, It is Lloyd's situation I'm trying to deal with, not yours, Dimi's or mine. So, as a reminder:
- The only existing ports are halfway up the side of his fuel cells.
- He cannot make any additional ports in his fuel cells.
- Therefore, he cannot have "a bottom cross over line that keeps the fuel tanks even"
Thirdly, my later solutions don't use any electronics.
Finally, my earlier posts show that you, Dimi and I are all in violent agreement about how to do this when you can have "a bottom cross over line that keeps the fuel tanks even".
Lloyd (the OP) does not have that option.
Seymour Snerd
Lifetime Supporter
I think it's self-evident that watching two things is "harder" than watching one. But that's being a little pedantic.
And besides that's not really the point. The issue is that if you don't a) watch, and b) switch tanks at the right time you run out of fuel. Possibly in mid-turn. Lovely.
By way of analogy the surface of the earth has been littered with the wreckage of airplanes that fell because the pilot, while having plenty of fuel, mismanaged his tank switching.
Simplicity, when you can get it, is a good thing especially for system reliability.
And remember, the original poster (Lloyd) appeared to me to be looking for something simple. He said: "...i need to come up with off the shelf simple solution." I don't recall being able to switch tanks manually being a requirement, and if it's not it certainly contributes nothing but complexity.
J found the Kinsler shut off valve nice unit its now on my parts list
Alan
what is the issue with running the tank dry. I understand the the engine cuts out. how hard is to restart when you switch to the other tank. I've never run out of fuel in one of the tanks yet. Not saying its impossible. i currently have two tanks with two pumps. I usually run the carb dry when i pull into the garage is seems to start pretty easy from a dry carb. How long does it take to push the air through the injectors?? Just curious it can't be as bad as running a diesel dry.
thanks
Lloyd
Alan
what is the issue with running the tank dry. I understand the the engine cuts out. how hard is to restart when you switch to the other tank. I've never run out of fuel in one of the tanks yet. Not saying its impossible. i currently have two tanks with two pumps. I usually run the carb dry when i pull into the garage is seems to start pretty easy from a dry carb. How long does it take to push the air through the injectors?? Just curious it can't be as bad as running a diesel dry.
thanks
Lloyd
This thread has definitely "jumped the shark"...
Running dry isn't an issue unless it happens at 100mph under braking in turn 13...500hp bucking and spitting in that situation could make you change your underwear.
Couple of things...
1st you have to decide whether you want the two tanks to function as one, or have separate tanks.
If you want them to function as one, then any balance tube other than one at the bottom and one at the top is a bad idea and at no point should the tube on the bottom rise above the top of the tank.
If separate then the simplest solution is separate pumps and a switchable return. If you're hell bent on one pump then Parker makes a 6port marine valve that would work. The 6port switch NAPA sells (Pollak) will work if HP is sub 400.
Finally, if you're going to run an EFI pump straight from the tanks you should baffle the tanks so that the pump doesn't "gulp some air". If it does the engine dies or sputters until the air is expelled. Carbs don't suffer this because there is fuel in the float bowls. The tanks are long and shallow with no sump, so you couldn't design a worse tank for EFI if you tried. This may not be an issue in casual driving, but is certainly going to happen once the tanks are low on a race track or any spirited driving.
Seymour Snerd
Lifetime Supporter
Not an issue as long as you're expecting it although see Ron's comments re: EFI above.
Seymour Snerd
Lifetime Supporter
Meaning? (Sorry, I'm not a Happy Days fan).
thanks for all the comments gentlemen. You guys are a wealth of information. I might add the car is strictly street use. Most miles are to and from Shows. I should have put that up front it might have changed the direction some people took.
Right now i'm leaning to two pumps with two check valves and switched valves on the return lines. I can utilize the existing 12 volt supply to two pump. I was trying to stay with the two power supplies controlled by two dash switches. I also have an oil pressure switch controlling power to the pumps (safety). if that doesn't work for street use i'll go with a swirl tank. Little more complicated but solves all of the issues.
LLoyd
Right now i'm leaning to two pumps with two check valves and switched valves on the return lines. I can utilize the existing 12 volt supply to two pump. I was trying to stay with the two power supplies controlled by two dash switches. I also have an oil pressure switch controlling power to the pumps (safety). if that doesn't work for street use i'll go with a swirl tank. Little more complicated but solves all of the issues.
LLoyd
Ian Anderson
Lifetime Supporter
Bob
That's a great system
Have you got some device in mind for your "Air Bleed" I could not find anything suitable so ended up running a pollack valve
Ian
That's a great system
Have you got some device in mind for your "Air Bleed" I could not find anything suitable so ended up running a pollack valve
Ian
Bob,
Is the air bleed a manual thing, or something electronic? If manual then how does the air taken in by the LP pumps work out of the swirl pot?
I assume that the LP pumps have an integrated regulator?
Is the air bleed a manual thing, or something electronic? If manual then how does the air taken in by the LP pumps work out of the swirl pot?
I assume that the LP pumps have an integrated regulator?
Although it takes a little more engineering, I was thinking of a simple float-actuated system from a carburetor to do it. It just makes fabricating the swirl pot that much more complicated.
If the system has return lines to the tanks (which require shut-off valves), I would bleed the air through a restrictor to the return line (before the valves). That way, no float would be necessary.
If the system has return lines to the tanks (which require shut-off valves), I would bleed the air through a restrictor to the return line (before the valves). That way, no float would be necessary.
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Terry Oxandale
Skinny Man
Bob's system (modified diagram below) is basically the same approach I used in my system with the exception of bleeding the swirl pot back to the "primary" tank only (no T-fitting or valving). I plan on running off the "primary" tank (passenger side) most if not all of the time, and when the "secondary" (other side tank) is used on those rare occasions for long trips, the fuel continues to bleed out of the swirl pot back to the primary tank (it bascially acts as a transfer circuit from the secondary tank, to the swirl pot, and then to the primary tank).
Can any of you computer gurus explain the previously unseen watermark that shows up on this when I modified Bob's document it and sent it back? Is this a watermark inserted by this site?
Can any of you computer gurus explain the previously unseen watermark that shows up on this when I modified Bob's document it and sent it back? Is this a watermark inserted by this site?
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Given a narrow-enough path back to the tank, fuel flow would be very small to the overflow tank. Drain that tank down first, keep an eye on the fuel gauge, and it would be a simple solution.
Re: the watermark: What are you using for screen capture? Are you saving the image to your computer first? Instead of the screen capture, right click on the image and save it before you add your changes.
Re: the watermark: What are you using for screen capture? Are you saving the image to your computer first? Instead of the screen capture, right click on the image and save it before you add your changes.
Flow back to tank is only relevant to the amount of fuel passed to the extent is increases back pressure. The flow to the the tank will be:
GPH (LP Pump @ back pressure PSI - 2psi on the diagram
less fuel consumed by the engine (less or none at full throttle high rpm, a lot at idle).
Ron,
I'm not sure that I understand your post.
Pressure in the swirl pot is solely a result of the pressure from the low-pressure pumps, and it should remain constant (assuming the low-pressure pump has enough volume to feed the high-pressure pump flow). You could probably get away with 3-4 psi since there's basically no resistance to flow into the swirl pot.
Fuel bleed-off through a small orifice or small return line could be as low as a couple gallons/hour and still pass whatever air gets trapped in the pot.
I'm not sure that I understand your post.
Pressure in the swirl pot is solely a result of the pressure from the low-pressure pumps, and it should remain constant (assuming the low-pressure pump has enough volume to feed the high-pressure pump flow). You could probably get away with 3-4 psi since there's basically no resistance to flow into the swirl pot.
Fuel bleed-off through a small orifice or small return line could be as low as a couple gallons/hour and still pass whatever air gets trapped in the pot.
Terry Oxandale
Skinny Man
Correct. My rationale was that if the pressure dropped in the swirl pot, then obviously the LP pump(s) are not keeping up with fuel demand. How much of a deficit would be hard to observe, but my calculation are that if the LP pump fails completely, I could run at least 30 seconds at WOT and load before draining the swirl pot empty.
Seymour Snerd
Lifetime Supporter
Bob -- just a side question for my own education: in what scenarios are the check valves active? I assume that when both LP pumps are running the check valves don't do anything particularly useful (?). Or are they needed under normal conditions due to slight difference pressure between the two LP pumps? Are they there for when one pump fails, or one tank runs dry, or ....?
I'm sure I'm confused (one of those days). This is also a test to see if I'm thinking about this right.
I assumed the "overflow" tank you referenced was the "right tank" in the diagram.
If so, then the LP pumps are going to flow as much fuel as they can at 2psi regardless of engine demands as they are oblivious to anything but the 2psi regulator. Because the line behind the 2psi regulator is "free flow" the regulator is going to flow continuously. There is no way to dead-head it like you would with carburetors when the float bowls are full.
The EFI is going to scavenge from the swirl pot what the engine consumes.
The excess (if any) is going to flow to the "overflow" tank.
CRUDE MATH ALERT!
Assuming you're cruising down the road at 70mph getting 20mpg the engine is consuming 3.5GPH give or take. Those sweet billet Holley fuel pumps realistically flow about 70GPH at 2psi, so you're returning 66.5GPH to the "overflow tank". That means if the "left tank" is 10 gallons and full you'd empty the "left tank" into the "right tank" in 8:34.
Further, I think the regulator is going to act like a check valve which means that if the demands are greater than than the LP pumps can supply it is going to vacuum it past the pumps or you'll lose pressure across the rails. I made sure my LP pumps would always flow more than the engine demanded and that there was no check valves or regulators behind my surge tank.
Best,
Ron
I assumed the "overflow" tank you referenced was the "right tank" in the diagram.
If so, then the LP pumps are going to flow as much fuel as they can at 2psi regardless of engine demands as they are oblivious to anything but the 2psi regulator. Because the line behind the 2psi regulator is "free flow" the regulator is going to flow continuously. There is no way to dead-head it like you would with carburetors when the float bowls are full.
The EFI is going to scavenge from the swirl pot what the engine consumes.
The excess (if any) is going to flow to the "overflow" tank.
CRUDE MATH ALERT!
Assuming you're cruising down the road at 70mph getting 20mpg the engine is consuming 3.5GPH give or take. Those sweet billet Holley fuel pumps realistically flow about 70GPH at 2psi, so you're returning 66.5GPH to the "overflow tank". That means if the "left tank" is 10 gallons and full you'd empty the "left tank" into the "right tank" in 8:34.
Further, I think the regulator is going to act like a check valve which means that if the demands are greater than than the LP pumps can supply it is going to vacuum it past the pumps or you'll lose pressure across the rails. I made sure my LP pumps would always flow more than the engine demanded and that there was no check valves or regulators behind my surge tank.
Best,
Ron
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The ERA is set up to use 1 pump at a time or both pumps simultaneously. If you're only running one (low-pressure) pump, it may be possible for fuel to back-flow through the other pump without the check valve in the circuit. Some pumps have built-in check valves though.
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