surge tanks and pump options

[Herman Pahls]

The Phoenix F-1000 I purchased came with a fuel cell but no pump.
Another Phoenix owner told me that to prevent surging he needs to allow for an extra 2-3 gallons in the fuel cell.
My Sportsracer required a surge tank with a low pressure pump feeding the surge tank.
ATL makes a "black box" with check valves and high pressure pump.
The reviews on that product have not been perfect.
Also, some have questioned the safety and or legality of a seperate external surge tank.
I am considering installing the ATL "black box" without the check valves.
Use a low pressure pump to feed the "black box" thru the slit in the top.
Have the high pressure return line go into the top of "black box",
and then have the high pressure pump feed out of the "black box" with either an internal or external high pressure pump.
I would appreciate your opinions or suggestions.
Thanks Herman Pahls Oregon 541 404 6464

[RussMcB]

Personally, I really like the set up where you have a low pressure pump feeding a small remote reservoir, which feeds the high pressure pump. The small reservoir tank has an overflow hose that goes back to the cell. In my mind, this is the absolute best way to make sure the high pressure pump never sucks air until the cell is almost completely dry.

This set up also makes it less critical where the pickup is in the cell (front, back, sides). It's no problem if the low pressure pump sucks air for a second, during braking, cornering, whatever.

GDRE recommends a good aftermarket high pressure fuel pump and regulator so you can make minor AFR changes, such as, for different altitudes.

If your pressure regulator has an external outlet (mine doesn't), you can have it feed either the small reservoir or the cell. If you want to run the car to the last drop, have it feed the small reservoir, but the down side is your fuel may be a little hotter since some of it is coming directly from the fuel rail.

[dereklola]

ATL makes a "black box" with check valves and high pressure pump. The reviews on that product have not been perfect.

Herman - care to elucidate? I've been using them for 15 years now and narry a problem - one low pressure pump, one high pressure - both located in the 'black box' as you call it.
Thx - Derek

[Rilltech Racing]

deleted...

[JakeL]

Herman -

The separate external tank is a pretty common solution. I had an in-cell "surge tank" in my Radical, with a Fuel Safe cell, and it was insufficient to prevent starvation on low fuel.

I switched to an external "fuel pot" being fed by a low pressure pump. The pot had a stock Suzuki pump inside, and it worked flawlessly.

My Stohr has an in-tank home-brew looking pot which is fed by a low-pressure pump - same basic idea, except the fuel pot is contained within the fuel cell.

Rilltech Racing has a nice fuel pot that I used on the Radical, and a low-pressure pump for a good price ($200ish, I think) that works quite well. I think Stu Waterman has a similar setup on his Speads FB.

Cheers!

-Jake

[10rmotor]

Herman, who has been questioning the legality of an external fuel tank? This very setup has been through national tech many times without problems. External tanks have been in use for decades literally. I've seen them on Lola F5000 cars I've worked on.

You can get facet low pressure pumps for much less than 200 bucks(!). Heck, you can get high pressure bosch pumps from summit for less than that. I like external pumps because if/when they fail, they're easy to replace.

If you dead head the fuel rail, the fuel shouldn't be heated near as much. The only heating comes from the heated and bypassed fuel through the regulator back into the external tank.

[Mike Devins]

If you dead head the fuel rail, the fuel shouldn't be heated near as much. The only heating comes from the heated and bypassed fuel through the regulator back into the external tank.

How do you dead head the fuel rail with out bypass since the regulators are normally bypass regulators. I would suggest that you run the bypass back to the main tank.

[RobLav]

Mike - my 06 R1 had a bypass regulator, whereas the 07/08 R1 engine I am installing now has a deadhead fuel rail.

[10rmotor]

Mike, its real simple. My regulator (an aeromotive) is a bypass regulator, so it has a bypass port that dumps the excess pressure back to the surge tank. The other ports are pressure adjusted. One of these connects to the fuel rail through a fine sintered element filter. Fuel entering one end of the fuel rail can only go through the injectors, no where else.

[Mike Devins]

I do not see what the difference where the regulator is in relation to the fuel rail. The fuel still gets hotter when it is compressed and does not loose that much heat when the pressure is released, eventually you will heat the surge tank although it may be slowly enough that you will not see the change in a way that will effect performance.

I my first install I had the bypass simply go back to a T in the fuel line before the fuel pump. Five minutes of idling and you would have 180 degree fuel.

[10rmotor]

It doesn't matter where the regulator is, I'm just talking about the fuel rail itself. The fuel rail is most likely the component that heats the fuel the most, so not running the fuel through the rail, and instead dead heading it so that the fuel at its hottest point isn't being circulated through the make up tank should keep the temperature down. I have not tested the temperature of the make up tank after a few minutes of idling.

[ny_racer_xxx]

If you run a surge tank with no vent, just supply and discharge, there's no need for a low pressure pump. We ran this type of system on my Superkart.
I'm building a F600 with a CBR600rr fuelie, and I plan on running a stock Honda fuel pump with a external regulator, return back to the main tank.

CR

www.cr2fabrication.webs.com

[glenn cooper]

What exactly is the fuel temerature when heated as opposed to the temp at initial startup?

[10rmotor]

NY_Racer, how do you have a fuel tank/cell, an external surge tank and only one high pressure pump, no low pressure/lift pump with your system? Are you saying your surge tank is in the fuel cell? If the surge tank is (I assume) external, how does it get filled?

[ny_racer_xxx]

The sump is external, the pump is ahead of the sump and between the sump and the fuel rail. It will draw the fuel through as if it was one tank if there is no vent on the sump. What I do is have a filling "port" basically a sealed cap on the sump to fill it to the top. Once that filled, and the sump is sealed, it will draw fuel from the main tank. It's the same as if you had a really long fuel line, it works as long as there isn't any air leaks in the fuel line.

Chris R.

[glenn cooper]

Lost me there!

[ny_racer_xxx]

OK s-l-o-w-l-y......

Fuel tank piped directly to the sump tank, out of the sump to the fuel pump. That's it!

CR

[Mike Devins]

OK s-l-o-w-l-y......

Fuel tank piped directly to the sump tank, out of the sump to the fuel pump. That's it!

CR

The issue is that as soon as you have cavitation at the pick up in the main cell you will suck air into the surge tank - the purpose of the low pressure pump and the return is to keep the surge tank filled.

[RussMcB]

I can't think of any benefit of that arrangement, other than slightly more fuel capacity.

The big benefit of a low pressure pump feeding an external tank is it greatly reduces the chance of the high pressure pump sucking air.

[lancer360]

I guess because of the lower g-forces of a F600, I don't use a surge tank and it works just fine. I use a Walbro GSL393 high pressure external pump and an Aeromotive 13105 compact EFI regulator. My system flows from the pump to the fuel rail and then back to the regulator which has a bypass hose back to the cell. According to Aeromotive the correct way to plumb the system is to have the regulator after the fuel rail. I think this is to ensure that full flow is going to the fuel rail. If the bypass regulator is before the fuel rail, you are loosing part of your flow.

[ny_racer_xxx]

I can't think of any benefit of that arrangement, other than slightly more fuel capacity.

The big benefit of a low pressure pump feeding an external tank is it greatly reduces the chance of the high pressure pump sucking air.

Well in order for it to suck air, the sump tank would have to be dry. Remember, there's no vent on the sump so the fuel pump will pickup fuel from the whole tank, it won't slosh because it's full. The other benefit it that I can use a stock Honda fuel pump that bolts to the bottom or side of the sump tank.

It always worked on a 2g superkart...

CR

[ny_racer_xxx]

The issue is that as soon as you have cavitation at the pick up in the main cell you will suck air into the surge tank - the purpose of the low pressure pump and the return is to keep the surge tank filled.

Listen to how you described it, "surge tank". What does that mean? Yes, if the fuel sloshes away from the pickup, what will happen is the level in the surge tank will go down. As long as the fuel pump pickup in the surge tank doesn't suck air, it's all good.

Here's some hard numbers:

Walboro pump: 255 liters per hour=1.2 gallons per minute at max output. That means if you had a 1 gallon surge tank, the main fuel pickup would have to be uncovered for 1/2 a lap at most tracks for the surge tank to suck air!!!!

CR

[RussMcB]

Would it be accurate to say that what you are describing is like a straw with a fat part in the middle? The high pressure pump sucks from the top of a long (unvented) tube?

[Mike Devins]

The issue is this for me - other peoples experiences may vary.

An RF-95 fuel cell will have cavitation at the pickup with about a gallon of fuel in a 2g corner. FB's are easily capable of 2.8g's. So if you need to carry an extra gallon of fuel to eliminate the cavitation that is 7 lbs. a low pressure pump is a lb or 2.

That's 5 lbs I can put somewhere else or in a DSR lose the weight.

[ny_racer_xxx]

The issue is this for me - other peoples experiences may vary.

An RF-95 fuel cell will have cavitation at the pickup with about a gallon of fuel in a 2g corner. FB's are easily capable of 2.8g's. So if you need to carry an extra gallon of fuel to eliminate the cavitation that is 7 lbs. a low pressure pump is a lb or 2.

That's 5 lbs I can put somewhere else or in a DSR lose the weight.

OK, you lost me???? Where are you pumping to with the low pressure pump? You still need another reservoir that will hold another gallon of fuel???? So in actuality, the way you describe it, your system adds 1 to 2 pounds more, another electrical failure point, and several extra plumbing failure points....

Also, you don't have to "add" another gallon of fuel either. If it's a 4 gallon cell, you can put 3 in the cell and 1 in the reservoir.

I'm not saying what I described as being perfect, just another alternative that's a bit less complex.

CR

[10rmotor]

I think Russ explained it the best!

So how big is this "surge" tank, which I really don't think is the appropriate description? My accumulator/make up tank only holds about a cup of fuel - just about the same amount as four float bowls in the bott0m of 4 flat slide carburetors, which is what I'm simulating with this external tank setup.

Yes I understand the extra plumbing, wiring, complexity thing, but I never have to worry about fuel starvation anywhere. If it stumbles, I'm outta gas, and I'm good with that situation.

[ny_racer_xxx]

I think Russ explained it the best!

So how big is this "surge" tank, which I really don't think is the appropriate description? My accumulator/make up tank only holds about a cup of fuel - just about the same amount as four float bowls in the bott0m of 4 flat slide carburetors, which is what I'm simulating with this external tank setup.

Yes I understand the extra plumbing, wiring, complexity thing, but I never have to worry about fuel starvation anywhere. If it stumbles, I'm outta gas, and I'm good with that situation.

Your outta gas or the low pressure pump quit, or your sucking air through one of your extra fittings...etc....

Are you talking about a fuel injected motor or carb? I just picked 1 gallon as a round number, it could as small as what works, there's just no reason to add another pump. For that matter it could be an over sized fuel filter canister as the res.

CR

[lancer360]

CR

The problem with only have one pump and a surge tank is that when your pick up tube in the fuel cell is uncovered in a high G turn it sucks some air into the surge tank. This air has no place to go and becomes trapped in the surge tank. This works ok as long as you don't uncover the pick up tube in the fuel cell enough times to completely drain the surge tank.

The reason for a secondary low pressure pump is that it constantly circulates fuel into the surge tank and then out of the surge tank back to the fuel cell. This gives any air that may be sucked up when the pick up tube is exposed a path to get flushed back into the fuel cell.

[Mike Devins]

I hate the extra pump and the potential failure as well but the reality is that I was sitting along side of the track on the last lap a few years ago. When we got a flat toe back to the paddock we pumped a little over a gallon of fuel out of the tank yet I had no fuel pressure.

Maybe there is a different type of pump that I could be using for high pressure but the Bosch pump that we use will not prime it self unless you open up the regulator when is mounted higher than the level of the fuel which always will be when you are down to a gallon or so in the cell. We duplicated the failure later and the end result was a low pressure pump to a small holding tank and a return to the cell from that tank. The pick up for the high pressure pump remains submerged in the holding tank and is never uncovered.

In the event that the low pressure pump sucks air for a moment the high pressure pump has a small supply to continue operation. No DNF if you still have fuel in the cell.

If you would like give me a call and good luck with what ever solution you end up using.

[10rmotor]

Actually, there is only one line that if it sucks air creates a problem - the one connecting the make up tank to the pump. I use steel braided hose and AN fittings, so leaks really aren't an issue.

Yes, the low pressure pump could fail. A thousand other things could fail too, not sure why you're harping on a second fuel pump. Cars have had high and low pressure pumps for years without issue. Its also not rocket science to fabricate a robust electrical system. If you use good quality wiring and solder connections, its a non-issue.

I run this setup because IF a pump fails, its external, so I can change it in a few minutes. If its a single in the tank pump, I have to remove the cell and open it up. While that might not be too difficult on my car, there are others where this is an all day job. My fuel cell doesn't have internal access, so installing an in tank pump wasn't an option. Also, my cell is on the smallish side, and I didn't want the cost and didn't have the space for a larger new one.

From what I can see, all your extra tank does is provide a finite amount of unaerated fuel until it is full of air. After that point, the extra tank is just dead weight. I'm familiar with setups like yours. Typically they're used for extra capacity. And having to prime the second tank before every session? Forget it.

[lancer360]

Maybe there is a different type of pump that I could be using for high pressure but the Bosch pump that we use will not prime it self unless you open up the regulator when is mounted higher than the level of the fuel which always will be when you are down to a gallon or so in the cell.

The Walbro GSL393 pump that I use is self priming. It is external and mounted on top of my fuel cell, sucks through a filter and it still primes itself. I drain my fuel cell after every weekend so it has to prime itself everytime I go racing and it hasn't ever been a problem. I'm not sure what flow rate you need so here is a chart for it. It is reasonably priced and pretty easy to find at various online stores like Summit.

[glenn cooper]

Nomenclature is everything in this game.

"Sump" does not equal makeup tank

"Vents" on the make up tank - is that like a screen door on a submarine?

Finally, what induction system is used on the superkart mentioned previously?

Thx, GC

[ny_racer_xxx]

Nomenclature is everything in this game.

"Sump" does not equal makeup tank

"Vents" on the make up tank - is that like a screen door on a submarine?

Finally, what induction system is used on the superkart mentioned previously?

Thx, GC

Whatever, just trying to help, you can a lead a horse to water......

CR

[glenn cooper]

Yeah man, my fuel system is totally sorted, so I too am just trying to help, just like everyone on here.

Just gotta know the situation in order to provide input.

So - What induction system was/is on superkart - Carbureted, or injected?

THX, GC

[Herman Pahls]

Please correct me if I am wrong.
It seems like the perfect fuel cell would be small in diameter and however tall to get the needed volume. This design would not be practical to package in a race car.

My 07 Phoenix F-1000 came with a 8 gallon cell. One Phoenix owner said he needs to keep 2-3 gallons in the cell to prevent surging. That adds 18 pounds.

The 5 gallon rectangular cell with foam in my homebuilt sportsracer (Hayabusa) would allow surging after 10 minutes on the track.

A low pressure facet pump feeding a one quart surge pump with the return going to the surge tank and a vent line back to the main tank has performed flawlessly.

I would prefer a simpler system and hope this forum comes up with a practical design.

I do not understand how the non vented surge tank as mentioned earlier will work unless it is below the main tank and gravity fed. Would it need a air bleed to get the air out when filled initially?

I assume carborated engines would be much less effected by fuel sloosh than injected.

Thanks Herman

[10rmotor]

Carbureted engines don't need all this because they have the function sort of built in - they're called float bowls. If the fuel pump sucks air for a few seconds the float bowls still have fuel in them. If a fuel injected high pressure pump sucks air for even a few seconds, that air will make it to the fuel rail and blow air through the injectors with stumbling as a result.

[ny_racer_xxx]

If you run the regulator after the fuel pump with the return back to the tank, that will eliminate a lot of air troubles.

A float bowl is a can of worms on it's own!!!

CR

[10rmotor]

If you run the regulator after the fuel pump with the return back to the tank, that will eliminate a lot of air troubles.
CR

No it won't. It will just get worse as the fuel level drops.

[ny_racer_xxx]

Again, if you use a surge tank and position the regulator as I said, it will help reduce if not eliminate the air by purging the air back to the main tank.

CR

[Herman Pahls]

OK S-L-O-W-L-Y
By the way CR you maybe up to something with your design.
What I precieve to be arrogance on your part may be acceptable if your building and racing skills have put you near the top of your class on a national level.
How is your none vented sump tank shaped, sized and oriented in relation to the bottom of a wedge shaped fuel cell that is typical to Formula cars?
You mentioned earlier that it has a fitting to remove the air at initial use which would be neccessary.
It seems your design would need to be below the bottom of the fuel cell in order to not need a low pressure transfer pump to make use all available fuel without surging.
Herman