speedtigger

iTrader: (16)

Since my LS swap, a constant problem has been the poor fuel control of the factory tank. It is several feet wide. a couple feet long and only 4" to 6" tall with no baffling whatsoever. With an electric fuel pump and return style fuel system, this means fuelus interuptus whenever I accelerate, or turn hard with anything less than a full tank of fuel.

When I go drag racing, if my tank is not full the fuel pressure fluctuates drastically and many times just disappears to 0.

So, after considering fuel cells and aftermarket tanks, I decided the best option for my needs was a custom sump/baffle modification. This thread will detail this upgrade.

Here are many pictures showing the template, mockup and design:

The template was designed to be 12" wide, 13" long and 4 1/2" tall. The reason for the dimension was a compromise between maintaining ground clearance while still having a sump/baffle that would maintain over 1 gallon of fuel under the harshest accelleration. 1 gallon is more than enough for a full quarter mile pass - even on a high 9 second nitrous pass. In fact, my 150 gallon per hour pump could not empty this baffle/sump if it was wide open and unrestricted for 13 seconds. Here is the template in cardboard:


The initial mock up of the sump/baffle in stainless:


You can see the additional dividers inside. They will help maintain fuel when cornering and control "slosh". They go all the way to the front, but stop 1/2" short of the back of the sump/baffle. This will allow access to the fuel for the pickup, but slow the fuel from exiting the sump via the feed holes on the front which have not been drilled yet, but can be seen drawn on the cardboard template in the first photo.


In this picture, you can see where the pickup tube feeds the bung/AN fitting. The rear is pointed to keep the fuel concentrated at the pickup opening when the fuel level is low. I speculate it also improves fuel control. Note the second bung for fuel return. It is located in a side section to discourage fuel turbulence near the pickup tube.


This picture shows the sump/baffle top cover sitting in place. This cover will not enclose the top of the sump/baffle completely. It is not necessary and will stop air pockets from becoming trapped inside. I may make the cover even longer, but I doubt it is necessary. It's primary function for me is the keep the fuel from flowing over the back under hard acceleration.


Here is the patient. A new stainless steel factory replacement tank. Stainless was chosen so that tank would not rust where welded. And, for only $220, it is a great buy.


This is where the sump/baffle will be inserted into the bottom of the tank. The most difficult part of this process will be cutting a precise hole in the bottom of the tank for a nice tight fit. This is important for easy welding of the thin stainless.


The pointed side of the sump/baffle goes toward the rear of the tank, while the flat side with the fittings goes toward the front of the tank flush with the front. Inside the tank, there is a piece of 1/2 stainless tubing that draws fuel from the rear of the sump/baffle assembly. This tubing is welded to a bung that is threaded 1/2 pipe which has an 8 or 10 AN fitting threaded into it.

A large hole the size of the sump/baffle will be cut in the bottom of the tank. The sump/baffle will be inserted from the bottom and welded in with the assembly protruding from the bottom of the tank 1 to 1 1/2 inches. There will be 1 inch holes cut in the baffle side walls about 1 1/2 inches from the bottom at the front of the baffle/sump. If you look at the cardboard template, you will see the location of these holes drawn on the sides. These holes will let the fuel into the sump/baffle

bczee

iTrader: (12)

I have been considering and think of doing something like this for my Nova project.. It is also much like the Aeromotive Stealth system setup.. pretty much like putting a pot into the area as a sump with fill holes.. I'll be following your setup, will start working on my Nova tank in Jan/Feb time.

BC

1989GTA

That should work. What system were you using? I have the Tanks Inc setup and I hope that is enough.

gofastwclass

iTrader: (2)

Cool idea, thanks for sharing.

Jimbo1367

Why not just put a baffled tray inside instead? I bought a Ricks 340 tank and took it apart to see how they baffled it, I expected elaborate baffling. VERY simple design. I hope it works as advertised.

Jim

LS1 pwrd NOVA

iTrader: (2)

Pics of this....

Doug G

Maybe just pop a few (5) 1.5"-2" holes in tank and trim the sump to fit flush to the bottom and weld....much easier.

krwyellowZ28

iTrader: (10)

I was thinking the same thing... especially since your design has the return feeding the sump directly. Great workmanship, too!

speedtigger

iTrader: (16)

This is not how my sump/baffle is designed. This sump/baffle will contain over 1 gallon of fuel. If it was all hanging under the tank, ground clearance would be an issue. Once I cut and place the sump/baffle it will make more sense visually.

ls1nova71

iTrader: (4)

I did something similar to my Nova gas tank, bent up a square box and welded it half in, half out of the tank. It probably holds a gallon too. However I didn't put a big enough top ob it since I'm using an in tank pump, and it will slosh out most of the gas away from the pump on hard acceleration with a very low tank. Using an external gravity fed pump like yours should work better. Nice job on it so far, I'll be watching this.

speedtigger

iTrader: (16)

So after coming up a scant .07 short of hitting ten seconds without using nitrous, I decided to get back to work on my gas tank mod.

Check out the progress. Just have to tig it up now:

bczee

iTrader: (12)

Speed,

I was able to finish my fuel tank mod.. see my thread, page #11 or Post #201

https://ls1tech.com/forums/conversio...ls1-a4-11.html

Mine is for EFI and I used the TanksINC PA4 kit.. we both used the same Idea of putting a sump/bucket in from the bottom..

I sealed it up and I used compressed air to check for leaks. but don't use too much or you will expand the tank too much and it might not return to it original form.

Hope yours works out ok.. My Nova is running, but not on the street or drivable ... as it is waiting for funds for weeks and tire (this month, Yeah !)..

BC

lizeec

iTrader: (57)

Is the sump going to interfere with the fuel sending unit, as the float will be right where you have the sump set in? Most sumps I have seen are towards the filler neck as that is where the fuel will slosh to on a hard launch.

speedtigger

iTrader: (16)

The sending unit is at the very front of the tank. I had to turn it 45 degrees and move it forward 1" to make it work.

bczee

iTrader: (12)

I was able to also make it work and it did clear the bucket, foam and PA4 pump/tray. I just had to cut the bucket a bit where it needed clearance and shaved the foam I put in the bucket to help keep the fuel in the bucket and tray.

BC

59belair

That looks really good Speedtigger.
This is quite a bit different than yours, in that it was a tank I built for my T bucket, but the idea is the same. this is obviously the bottom of the tank, but what you can't see is that the bottom of the tank, under the circular extension, only has one hole about 1/2" diameter in it to join the main tank with the sump. I use an external pump on this car, yet can run the tank down to the last quart of fuel and still never starve the pump.
Good for you for thinking outside of the box.

bitterman

Very nice tigger! Should work out perfect till you popping huge wheelies with the 65 and dragging the tank :O
Bruce

speedtigger

iTrader: (16)

Silly man. You know I checked it. The bumper hits first. Although as hard as it is to find a good bumper for a 65 Skylark, perhaps it would be better if the tank hit first.

speedtigger

iTrader: (16)

Here is the final test fit in the car:

bczee

iTrader: (12)

Looks good, tucks up well. It doesn't hang any lower than mine. Mine is just smaller in size

BC