Internal Fuel Pump - Slosh Pan

[James]

So, I'm in the middle of converting the tank to an internal design. Already cut a section of the top of, and since I have easy access to the tank floor. I was thinking about beefing up the baffling a little bit. Nothing extreme , just welding a slightly perforated aluminum box at the bottom of the tank about 3-4" high and 4"x4" square where the fuel sock and pump will sit in.

The pump itself will be attached to a beam that is attached to the tank cover and will sit inside. (Something close to the picture). I'm trying to see if there are any flaws in the design or if you guys have any other advice. The access hole will be about 3.5" (I'm welding in a 1/4 thick plate of T6061 on top where the whole cutout will be) so strength definitely is not an issue.

 

[Frank Clark]

For those that can do the fabrication, I personally think in-tank is the best setup for a true street car. But you will want the equivalent of a surge tank in any SLC. You can use an ATL unit off the shelf - look at their 3-door drop in unit which should fit well against the back-middle of the tank. Or you can buy their trap doors and build in any design surge tank you would like. I would be worried that simple baffling (without the trap doors) would cause starvation issues.

I assume other vendors have similar offerings.

You may also consider dropping the surge tank portion of your tank a bit as there is room to do that between the chassis supports. That would probably be best for anyone that runs their fuel down to the last few gallons.

 

[James]

For those that can do the fabrication, I personally think in-tank is the best setup for a true street car. But you will want the equivalent of a surge tank in any SLC. You can use an ATL unit off the shelf - look at their 3-door drop in unit which should fit well against the back-middle of the tank. Or you can buy their trap doors and build in any design surge tank you would like. I would be worried that simple baffling (without the trap doors) would cause starvation issues.

I assume other vendors have similar offerings.

You may also consider dropping the surge tank portion of your tank a bit as there is room to do that between the chassis supports. That would probably be best for anyone that runs their fuel down to the last few gallons.

LOL,, I was actually thinking about making a couple of one way trap doors, but wondered how practical that would be (guess it actually does work). If I don't have to fabricate it, might be nice,, even if it is a few dollars more.

Thanks for the info Frank.

 

[Will Campbell]

I guess opinions vary on this, but personally I'd rather have a LP and HP pump that are external to the tank. Why?

1. Because maintenance is so much easier (taking the tank out to replace a bad pump, replace a filter, or even to troubleshoot it when you have a full interior is some work),
2. Because running out of fuel ruins most HP pumps pretty quickly, and unless you use something like the ATL fabric surge tank (around $400) inside your factory tank, you will almost certainly run out of fuel when cornering with low fuel loads,
3. Because you don't have to do welding on the factory tank, which is potentially relatively expensive and requires another round of leak testing, if you've already done that,
4. Because it just seems to add complexity where it isn't required(at least to my eyes.)

I suppose on the benefits side, you don't have to buy a LP pump, and there are fewer lines and fittings, so there is that.

So what is driving the interest in in-tank pumps? Inquiring minds want to know...

 

[James]

Actually found a surge tank box from Fuel Safe for $126 with the trap doors.

Reason to go internal.

1. No need for external swirl pot and 2nd fuel pump (less complexity)
2. Quieter (fuel pump is housed in the tank and fuel which dampens the noise/whine)
3. Internal pumps last longer (they are cooled by the fuel)


Granted, it will make replacing the fuel pump a bit more cumbersome, but not by that much. I am going to be leaving the hole where the external pump would have been hooked up, as it would make it easier to drain it down most of the way.

 

[Howard Jones]

I did this. Simple and experience with the one track weekend I ran the car showed I was picking up all but a bit less than the last 1/2 gal. For anything less than a full on wheel to wheel race car that's just fine.

The blue pick up hose drops right down to the bottom of the small square sump in the center of the tank. Works very well.

 

[Mesa]

Mine is internal.

Benefit is much less plumbing, less space taken up in the engine bay (of which I have very little to spare). There is a built in one gallon sump with trap doors to make sure it does not run dry.

 

[Ian Anderson]

Has anyone tried the hydramat?
https://www.holley.com/news/articles/holley_debuts_new_hydramat_fuel_reservoir/

Ian

 

[Frank Clark]

All the benefits above are correct.

For the guys going for a "Super Car" rather than a "Race Car", I think the biggest benefit is Quiet. Who wants to hear and feel the drone of the pumps on a highway cruise?

That said, I'm not in the "Super Car" group, so I went for a LP pump feeding a pot with 2 internal HP pumps.

 

[Frank Clark]

Hydramat looks very interesting. But if someone wants to try it, talk with them out how they expect it to hold up in a street car. The general expectation for a race car is that things get serviced AT LEAST once a year. So it may be something that could deteriorate in a few years. Or it may not hold up to fuel with Ethanol in it. I am sure their tech guys would steer you the right direction.

I'd love that for our Sprint Cars - we typically don't weigh after heats, so could run the heat with just enough fuel and save 30 lbs....

 

[Ian Anderson]

Hydramat looks very interesting. But if someone wants to try it, talk with them out how they expect it to hold up in a street car. The general expectation for a race car is that things get serviced AT LEAST once a year. So it may be something that could deteriorate in a few years. Or it may not hold up to fuel with Ethanol in it. I am sure their tech guys would steer you the right direction.

I'd love that for our Sprint Cars - we typically don't weigh after heats, so could run the heat with just enough fuel and save 30 lbs....

I read somewhere that service life was 6years 60000 miles

Ian

 

[Ian Anderson]

Could an in tank pump be attached to one of those hydramat jobs?

I have never taken one apart so do not know what the pick up looks like

Ian

 

[James]

After looking at a few designs, it might be cheaper,, and better quality to:

1. Build a 3 sided aluminum box 5"x5" I think would work
2. Cut out square holes on the bottom for the trap doors (all sides)
3. Cut a piano hinge into 1.5" sections to act like one way doors (only open inward)
------found some .09" thick 2" aluminum hinges for about $25 for 2 feet.
4. Attach flaps to inside of box
5. Attach box to back side of tank.

Done.

 

[Howard Jones]

Keep in mind the reason for a trap door box pickup system. Their main purpose is to insure that at the end of a fuel run ALL the fuel is picked up and NONE is left. This allows the race team to very carefully plan the fuel load required for a given length of a race or stint. Hauling around at extra gallon or two of fuel to insure continuous and reliable pick up of the last drop of fuel would in most cases cost a pro team a good finish or even a win.

Street cars or open track cars do not have this requirement. Just dump a can of gas into it after each session or pull into a gas station when the tank get near the bottom. I keep my on track cars at least 25% full and fill to half full. When I run my GT40 on the highway I just fill the empty tank when I switch over to the other full one.

I would be much more interested in reliability. Having the pickup system stick a door or have a valve stick shut when you believe you have plenty of fuel left is a real bummer if you get stranded out on the track and cause the session to be screwed up to tow you back "out of fuel". Stuck on the side of the freeway is just as bad if not worse.

Home made trap doors are just the ticket to something getting loose, stuck, falling apart, etc. Make it so there's nothing to fail and keep it simple would be my advice.

 

[Luke S]

I played with the Hydramat at PRI. Just flat AMAZING I must say. I was planning a $1k external surge tank for Dragweek car. I really think I'm going with the Hydramat now as it comes in 1-3 pickup points and even -10AN fittings. It can and does move a tremendous amount of fuel. Holley rep didn't flinch at 1600hp use.

 

[Denny Hughes]

At WOT running around 170 I don't think you will hear any pump noise
Seriously KISS principle keep it simple. My car has the FIA bladder so external as Will said
is easy maintenance and you can isolate the noise with an additional shield between the pumps and interior with sound deadner

 

[Troy Truglio]

I know a person using Hydramat, in a road race car and says has not had a low fuel issue yet.

I am using the Radium FST-R with a surge tank, internal fuel pump, fuel pressure regulator built in and returnless. This did make it super simple to do.
- 6an out of fuel tank to walbro inline fuel pump to FST-R, out of FST-R overflow back to the tank. Super simple.

 

[Frank Clark]

LS engines typically run return less fuel system. With that, if you suck air, is there anyway for the air to get out of the system short of going through the injectors? That would imply you are running lean anytime you are running hard and uncover the fuel pickup.

 

[Aaron H.]

I'm also running the exact fuel pump setup the you show in your first post as well as Fuel-Safe check balls for fuel control instead of a trap door. I welded in a second compartment inside my fuel tank where the fuel pump resides.

 

[James]

I was trying to wait till I had everything done to post pictures.

For the cover I used rivet plates on the back side of the aluminum.

I created one way aluminum doors (had to grind the back side a little to ensure smooth open and close)

I still have to.

1. drill and set the power plug on the cap
2. connect pigtail to the power plug

and the big one

Get it all welded up!!!