Let’s talk about return style fuel systems

[beefcake]

everything is power dependant, pumps your running, etc...

most kits like fore and such you can run 25% no problem, now, you jump from 800hp to 1500hp, and launching the car, thats when you typically starve for fuel, not normal driving, and not even hits on the street. most of the time, 1/4 tank is where we recommend adding

i don't care if you have a "bucket style", you have a 1/4 tank, and triple 285s and nail it, you are sucking the $hit out of the fuel in the bucket

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[Angrey]

Forgive my ignorance. Do kits such as the Lehtal or Juggernaut alleviate the low fuel concerns? My research comes up with a general consensus that return systems = low fuel concern. But you have made it seem like it’s merely a case of what hat style is incorporated to the kit.

It's a matter of keeping the pumps surrounded by fuel. In the past, that was accomplished through baffles inside the tank or even better, having an inline pickup tube in a sump at the bottom of the tank.

Modern IRS cars have the fuel tank further forward (because of the rear suspension conflicts) and that generally involves a "saddle" style tank which creates a couple of problems. The biggest being fuel imbalance from one side to the other (over the hump) which on the mustang (and many others) is accomplished via a siphon system (which reduces/sacrifices some pump flow to draw fuel slowly from the passenger side). Many high flow aftermarket fuel setups create a starvation issue because in order to fit 3 pumps, they eliminate the bucket (for fitment and/or cost savings). Having a bucket or reservoir that holds fuel around the pump intakes while the car momentarily lurches and fuel sloshes rearward helps. Additionally, the siphon flow from the passenger side dumped into the bucket provides a small amount of continuous reservoir fill.

The simplest solution to solving low fuel starvation is a surge tank. A dedicated reservoir that's filled with a lift pump and then the main fuel pumps draw it down temporarily. But that creates location issues and having fuel components inside the firewall with you. (in fairness, there's fuel systems exposed to the interior of the firewall regardless and separated by a rubber cover and a steel ringed friction top).

Adding a bucket to the system provides some limited measure against dry pumps. A lot of aftermarket systems just say "racecar" and warn you to not flog it when the fuel level is low. The Radium hat has many positive features, one of them being fuel storage with a one way bladder valve at the bottom (so fuel can flow in but not out) and then obviously over the top when fuel level is high. It can reduce, but not totally eliminate inertia starvation. (long/extended rips where the rearward G force is maintained for several seconds on high hp/consumption systems will eventually suck it dry).

 

[LOL WUT]

It's a matter of keeping the pumps surrounded by fuel. In the past, that was accomplished through baffles inside the tank or even better, having an inline pickup tube in a sump at the bottom of the tank.

Modern IRS cars have the fuel tank further forward (because of the rear suspension conflicts) and that generally involves a "saddle" style tank which creates a couple of problems. The biggest being fuel imbalance from one side to the other (over the hump) which on the mustang (and many others) is accomplished via a siphon system (which reduces/sacrifices some pump flow to draw fuel slowly from the passenger side). Many high flow aftermarket fuel setups create a starvation issue because in order to fit 3 pumps, they eliminate the bucket (for fitment and/or cost savings). Having a bucket or reservoir that holds fuel around the pump intakes while the car momentarily lurches and fuel sloshes rearward helps. Additionally, the siphon flow from the passenger side dumped into the bucket provides a small amount of continuous reservoir fill.

The simplest solution to solving low fuel starvation is a surge tank. A dedicated reservoir that's filled with a lift pump and then the main fuel pumps draw it down temporarily. But that creates location issues and having fuel components inside the firewall with you. (in fairness, there's fuel systems exposed to the interior of the firewall regardless and separated by a rubber cover and a steel ringed friction top).

Adding a bucket to the system provides some limited measure against dry pumps. A lot of aftermarket systems just say "racecar" and warn you to not flog it when the fuel level is low. The Radium hat has many positive features, one of them being fuel storage with a one way bladder valve at the bottom (so fuel can flow in but not out) and then obviously over the top when fuel level is high. It can reduce, but not totally eliminate inertia starvation. (long/extended rips where the rearward G force is maintained for several seconds on high hp/consumption systems will eventually suck it dry).

What an excellent explanation! Thank you so much for taking to time to go through that, very beneficial information and makes perfect sense as you explained it. Very much appreciated!

 

[Whitedevil95]

What an excellent explanation! Thank you so much for taking to time to go through that, very beneficial information and makes perfect sense as you explained it. Very much appreciated!

Yes he does a great job of explaining it all. Basically any of the hats that still use a bucket I think the DW and the Radium for example will alleviate most of the low fuel issues. FORE, Lethal and others have an open hat design.

 

[illtal]

Yes he does a great job of explaining it all. Basically any of the hats that still use a bucket I think the DW and the Radium for example will alleviate most of the low fuel issues. FORE, Lethal and others have an open hat design.

There are options for those open designs too. Just costs more money and have more maintenance involved.

 

[bankyf]

I wonder if there is a HP level where the radium hurts more than it helps (i.e. consuming more fuel than can flow back into the bucket even at a half tank). Is there a point at which you are better off without the radium and keeping a closer eye on your fuel level? I currently have all of the parts for a brushless system that should support 1200hp. I have both a radium bucket and an open setup that I can use. I wanted the radium to allow running lower fuel levels but I do have concerns about sucking it dry. My use will be strictly drag racing.

 

[illtal]

I wonder if there is a HP level where the radium hurts more than it helps (i.e. consuming more fuel than can flow back into the bucket even at a half tank). Is there a point at which you are better off without the radium and keeping a closer eye on your fuel level? I currently have all of the parts for a brushless system that should support 1200hp. I have both a radium bucket and an open setup that I can use. I wanted the radium to allow running lower fuel levels but I do have concerns about sucking it dry. My use will be strictly drag racing.

Lol you should not have any concerns. You have the return, the pull from the saddle and the pull from the passenger saddle.
You have to remember At any given point there is a fluctuating level of fuel in each saddle. Also, the radium hat has more volume in it than the stock hat. It should work exactly like stock, but finding the limit fuel usage would probably require a big HP car.

Edit PBD have been using these in big HP cars with the id brushless controller. Haven't really heard of any problems.

 

[beefcake]

Lol you should not have any concerns. You have the return, the pull from the saddle and the pull from the passenger saddle.
You have to remember At any given point there is a fluctuating level of fuel in each saddle. Also, the radium hat has more volume in it than the stock hat. It should work exactly like stock, but finding the limit fuel usage would probably require a big HP car.

Edit PBD have been using these in big HP cars with the id brushless controller. Haven't really heard of any problems.

Most big hp cars, keep fuel in their tank...... fuel is the lifeline of the car.. i don't care what you have in the car, below a 1/4 tank...none of us with power are out there going wot making big pulls.

even hats with buckes.. i'm not doing wot blasts at 1/4 tank....

the volume of fuel being sucked is very high.... and i don't trust the siphons to keep up.

 

[illtal]

Most big hp cars, keep fuel in their tank...... fuel is the lifeline of the car.. i don't care what you have in the car, below a 1/4 tank...none of us with power are out there going wot making big pulls.

even hats with buckes.. i'm not doing wot blasts at 1/4 tank....

the volume of fuel being sucked is very high.... and i don't trust the siphons to keep up.

Lol
I didn't say it was a good idea.
I have build going and you wouldn't see me mashing throttle with less than half tank. Too much money to lose on some dumb shit.

In a perfect world I would go with a high volume surge as previously stated. But as of now that solution doesn't exist.

 

[Angrey]

Most big hp cars, keep fuel in their tank...... fuel is the lifeline of the car.. i don't care what you have in the car, below a 1/4 tank...none of us with power are out there going wot making big pulls.

even hats with buckes.. i'm not doing wot blasts at 1/4 tank....

the volume of fuel being sucked is very high.... and i don't trust the siphons to keep up.

I added two low pressure lift pumps to my passenger side that push (instead of siphon) into the Radium bucket. So I'm getting roughly 400 liter/hour of fuel dumping into and spilling over the bucket (when the pumps are on and running).

This adds complexity and solves a problem most people just chalk up to "don't run it low." I wanted the ability to stomp at whatever fuel level I have, so I was willing to pay the cost and the brain damage to resolve that.

For a drag only car, the old school "racecar" works. For a street car on E-85 and high power, I'm already greatly reduced for the entire tank, if I'm now relegated to only being able to stomp for half a fill up, you're talking about like 50-60 miles worth of range before I either have to fill up or drive conservatively.

Doing the calcs, at 1200 hp consumption, and the additional flow into the bucket from the passenger pumps, I can run WOT for over 20 seconds without starving the bucket. I'll run out of pavement before that happens.

 

[beefcake]

I added two low pressure lift pumps to my passenger side that push (instead of siphon) into the Radium bucket. So I'm getting roughly 400 liter/hour of fuel dumping into and spilling over the bucket (when the pumps are on and running).

This adds complexity and solves a problem most people just chalk up to "don't run it low." I wanted the ability to stomp at whatever fuel level I have, so I was willing to pay the cost and the brain damage to resolve that.

For a drag only car, the old school "racecar" works. For a street car on E-85 and high power, I'm already greatly reduced for the entire tank, if I'm now relegated to only being able to stomp for half a fill up, you're talking about like 50-60 miles worth of range before I either have to fill up or drive conservatively.

Doing the calcs, at 1200 hp consumption, and the additional flow into the bucket from the passenger pumps, I can run WOT for over 20 seconds without starving the bucket. I'll run out of pavement before that happens.

i'd love to see that tested below a 1/4 tank at 1200 hp

 

[Angrey]

Lol
I didn't say it was a good idea.
I have build going and you wouldn't see me mashing throttle with less than half tank. Too much money to lose on some dumb shit.

In a perfect world I would go with a high volume surge as previously stated. But as of now that solution doesn't exist.

Surge doesn't need to be high volume. Several solutions from Radium and others (dedicated surge tank OR an in well tank at the rear).

At one point I considered adding a 12 gallon well tank (with integral surge tank) which would have resolved the range reduction from E85. But the saddle complicates things so I'd end up running 3 sets of pumps and even with brushless for the main pumps, it kinda defeats the whole keep amps down efforts. The lift pumps don't draw that much (like 4 amps each) and can flow about 200 l/h but still, between losing trunk space, I just opted to beef up the Radium hat and like I said above, it acts as it's own mini surge tank for much longer than I'll ever need (even at low fuel).

 

[Angrey]

i'd love to see that tested below a 1/4 tank at 1200 hp

I've already done it several times Though I'm only pushing 1000 to the wheels right now, so probably 1125-1130 from the motor.

Keep in mind that during a WOT rip, the motor isn't drinking full value until it reaches peak, so some complicated math would economize/optimize it further. Crudely calculated, I have over 20 seconds of full flow required for 1200 hp, when in reality it's probably more than that.

The system functions essentially just like a dedicated surge tank would.

 

[illtal]

Surge doesn't need to be high volume. Several solutions from Radium and others (dedicated surge tank OR an in well tank at the rear).

At one point I considered adding a 12 gallon well tank (with integral surge tank) which would have resolved the range reduction from E85. But the saddle complicates things so I'd end up running 3 sets of pumps and even with brushless for the main pumps, it kinda defeats the whole keep amps down efforts. The lift pumps don't draw that much (like 4 amps each) and can flow about 200 l/h but still, between losing trunk space, I just opted to beef up the Radium hat and like I said above, it acts as it's own mini surge tank for much longer than I'll ever need (even at low fuel).

I'd prefer it to be for the range reason as you have stated. However, I think a high volume will work to keep the fuel cool(er). Also the saddle lift pump/pumps would be open flow. So you could use just the stock bucket which would work like stock and use up the fuel evenly all the way to the bottom. I deguise no one would run 5-7 gallons of fuel on the street or track before the lift would refill the surge.

 

[Cory S]

If Fore didn't give so many kickbacks to vendors, other systems would be used way more often. I'm going to go probably go 8.90-9.10's on a twin Ti274 Radium setup on E70+. Too many overkill products are being pushed. Period.

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