Fuel Tank Baffles

[Washout]

I'm now making mods to my GT fuel tank to accept fuel injection and was wondering if anyone had added baffling to their tank. Reading over the many posts about the hazards of fuel being sloshed away from the pickup shows a real need to avoid this problem. The swirl tank or dash pot looks like a cumbersome addition of tanks, pumps and plumbing. To avoid the extra expense and plumbing I'm thinking about adding baffles 6 inches either side of the fuel pickup from the bottom to within 2 inches of the top of the tank. That should assure fuel is available even with violent cornering and still allow the tank to fill normally. I'm concerned that if I bring the baffle all the way to the top it will take forever to fill the tank as you would have to wait for the fuel to transfer through the holes in the baffle.

Any ideas on this, what size holes should be drilled through the baffle?

[namba209]

I would think you only need to go as high as the top floor in the tank based on its shape. From what I've read here, the problem only surfaces at about 1/4 tank of fuel left. Depending on the driving "G" loading, I think a series of half circles 1/2" diameter at the bottom should suffice, maybe aboout 4-6 inches away from the pickup. That should trap about a gallon of fuel around the pickup, more than enuff for a straight stretch to refill the baffled area. Or just maybe a large coffee can, with both ends removed, over the pickup area with the half circles about an inch apart.

[Washout]

namba209

Sounds like the feed tanks we have in the DC-8, but they use a pump to keep the feed tank (50 gals) full. One other idea a racer gave me today was simply to make a cylinder maybe 6 inches long and 2" in diameter and place it between the tank outlet and the fuel pump inlet as a surge tank. You would not normally be able to empty that cylinder in the amount of time it would take to make a hard corner. If you run a vent line from it back to the tank it should remain completely full with no air gaps.

[namba209]

Yeah, that's where I got the idea from. I just went one further on mine by using an idea for the inverted flight tank off fighter type aircraft. Your racing buddy has a good idea. Two things I would suggest, mount it vertical, fuel in and the vent at the top, fuel out in, the bottom. Then maybe mount it inside the rear frame at the back wall. That where my first fuel filter is mounted.

[Mike Preble]

While you are working on the tank, how about installing a larger fitting for the fuel outlet like JEGS Fuel Cell High-Flow Bulkhead Fittings - JEGS

If there are any negative thoughts on this I would like to hear them as I am thinking of going to this to upgrade my fuel tank.

Mike

[Washout]

Since I already have the tank out of the car I'm going to go ahead and build the baffles but the reservoir tank idea would be good if you didn't want to pull the tank. I think I'll route the return line so that it dumps into the baffled area with the tank outlet. That way there should be some fuel replenishing the fuel burned even during cornering.

Mike, thanks for the link. I'll use that for the outlet.

[namba209]

Originally Posted by Mike Preble While you are working on the tank, how about installing a larger fitting for the fuel outlet like JEGS Fuel Cell High-Flow Bulkhead Fittings - JEGS If there are any negative thoughts on this I would like to hear them as I am thinking of going to this to upgrade my fuel tank. Mike

So far on Willit? I haven't had any fuel starvation problems using the orignal (OGTS) replacement fuel line, and I'm getting a good return flow back to the tank. Of course I haven't had any sustained high speed runs in the higher RPM ranges yet, but I'm running an engine almost twice the size of a 1.9. Time will tell, I guess.

[Washout]

I'm sure your right Ron, You're drawing twice or more the fuel that we will need. It just rubs me wrong to have a restriction if I can eliminate it.

You know pilots, we like to be "for sure for sure". The only time you have too much fuel is if you are on fire.

[markandson]

Take a look at this thread and the pictures that I posted.
http://www.opelgt.com/forums/fuel-ta...fuel-tank.html
I will try to find the pickup info. They are designed to act like check valves if they become uncovered by fuel so that you don't suck any air. I put two of them inside my tank, as you can see by the pictures. The tank is not in service yet, but I don't expect to have any starvation issues.
Did a search and found the fuel pickup info. they are by Walbro and available here Auto Performance Engineering - Walbro fuel pumps and more

[markandson]

Check out this thread starting at post 184, alot of good info on fuel tank modification, although this was not for a GT, but a lot still applies. It is the thread where I found the fuel pickup info.
http://www.opelgt.com/forums/opel-en...allybob-8.html

[namba209]

Originally Posted by Washout I'm sure your right Ron, You're drawing twice or more the fuel that we will need. It just rubs me wrong to have a restriction if I can eliminate it. You know pilots, we like to be "for sure for sure". The only time you have too much fuel is if you are on fire.

Yeah for sure, I hear that, or rather heard that when I was a crew chief. My job then was to be sure the bird was 99.999999% sure of coming back.
I double checked my system, static, by running both pumps, with the engine dead, to make sure I had ample flow back to the tank. And another check to make sure the surge tank would not run dry, by having the "boost" pump on and the high pressure pump on also, with nothing restricting high pressure pump output. Both checks came out good. I guess I could run another check for the output line from the tank, through both pumps and dumping in a portable gas can, but I think, I've covered the flow requirements with the two previous checks. One of these days, I just might make a high speed run, just to see if it will take less than 3.5 miles to peg out the speedo, which was the reason for the swap in the first place.