Sumped Tanks-External Pump.....Best fuel line routing?

[jdpolzin]

I got into a debate with a friend of mine on this subject and would like to hear opinions and or facts from the guys that have used sumped tanks. Not interested in the opinions of those who have never used a sumped tank.

Here's the deal, we sumped a tank on Austins car and coated it with Eastwoods sealer to protect the welds from rusting. Well last year on the Power Tour, we found out that was a bad idea because the coating plugged up his filters. So I've been waiting on a stock style hanger to come out with -10 capabilites to be used on an external pump.
http://www.turbobuick.com/forums/e85-technical-forum/294822-trick-billet-fuel-tank-pick-up.html

Well after looking at the hanger once it's come out, I'm not sure if I
m fond of the set up so I'm going to go ahead and sump a tank. It would be nice if someone came out with a nice fabbed sumped tank that was affordable and not aluminum but it's not happening.

Now here's where my question comes in, some people are buying sumps with 1/2" or -10 outlets and using one for the feed and one for the return. Others are buying sumps with smaller 3/8" or -8 outlets and using a "T" to feed into a -10 line, using both outlets to the feed the pump then coming back with a return dumping into the higher sides of the tank. Others are dumping directly into the top with their returns.

Now with the fuel returning at the bottom into the sump, it's technically going to create more drag on the pump because it has to push it into the tank?

With the return on the higher side of the tank, could still cause drag on the pump if the tank is full of gas? And whos knows if the fuel is spraying onto the hanger causing problems. How about air bubbles in the tank?

Coming into the top creates a couple problems in my eyes. First there isnt enough room to 90deg on the top of the tank with a -8 return becuase the tank sits too high and the fitting will hit the body tub. And if you return to the ttop of the hanger, your going to be spraying directly onto the hanger. Air bubbles in the fuel?


So, with those statements made, please correct my thoughts if I'm wrong. Also what is the best route in your guys' minds?

 

[GNVYUS 1]

I have a baffled sump on my GTO, I run the -12 out as level as possible to the pump to help with gravity feeding it and not dry pumping on start up. What people are going to see with a sending unit that feeds an external pump higher than the tank is that the pump life will suffer due to dry pumping on start ups. Not only does the pump in the tank not deal with this, but the fuel acts as a cooler to the pumps motor heat. This is why running the internal with an external is great for fuel injected FI cars.

The return should be on the top to alleviate any return issues back at the fuel regulator. It's possible if the return was large enough and pump not that huge you could get away with the return at the sump, but it lacks common sense IMO. The stock GN tank has the return at the top, engineers have had this answered for decades.

Ricks Hot Rod Shop has an expensive SS sumped tank, maybe they'll do one in aluminum or steel for you.

 

[regal81455]

I spoke with comp engineering about this exact same issue and they indicated there was no problem with using the 2nd nipple for a return. Just my 2 cents...

 

[turbofabricator]

In my opinion, I would suggest returning fuel away from the pump pick-up to reduce cavitaion. Just bend the return line away from the inlet at the bottom. If there is not enough room between the trunk floor and the top of the tank for larger fittings, cut a notch in the trunk and weld or rivet a relief pan over the area. At this point of modification, you have already welded the roll bar to the chassis, narrowed the rear frame rails, ect. so why worry about notching the trunk floor pan? silly. Get the "zippy whee"l out and make it happen. You can always weld a patch panel in and return the car to stock. (like you ever really plan to do THAT.)

 

[jdpolzin]

I did think about notching the trunk pan and I wouldnt personally be worried about it ever going back to stock becuase it will never happen unless I die and my son turns into a purist! But, I'm more concerned with others and their cars. It wouldnt hurt Austins car either.

Now, how about internally in the tank? If you weld a bung on the top to except a -10 AN fitting, wouldnt the returning fuel act like a fish tank and airate the fuel?

I did see the SS tanks that are around $2000 but theres no way in heck I'll ever spend that kind of money on a gas tank. Welding on a stock tank creates a huge risk of internal rust issues. So what the best option?