dpuma8 Posted October 23, 2011 Share Posted October 23, 2011 I am trying to figure out where to mount my surge tank and I am wondering if the surge tank height matters in regards to the return line. I am planning on putting the surge tank next to the gas tank so does the return line from the surge tank need to be downward sloping to the gas tank? Or does it not matter? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted October 24, 2011 Share Posted October 24, 2011 I mounted it just in front of the fuel tank up against the bottom of the hatch floor and have had no issues. As long as you plumb it properly, I don't think the height matters - the low pressure pump is moving the fuel, not gravity. Quote Link to comment Share on other sites More sharing options...
dpuma8 Posted October 24, 2011 Author Share Posted October 24, 2011 What about the return line? gravity doesn't matter when returning from the surge tank to the gas tank? Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted October 24, 2011 Share Posted October 24, 2011 What about the return line? gravity doesn't matter when returning from the surge tank to the gas tank? No, It doesn't matter, the low pressure pump feeding the surge tank will push the fuel out of the return line and into the gas tank when the surge tank gets full. The surge tank may become slightly pressurized, but that's really a good thing, having a slight pressure against the inlet of the high pressure pump. Quote Link to comment Share on other sites More sharing options...
mark Posted October 24, 2011 Share Posted October 24, 2011 If plumbed correctly, the overflow goes back to the tank. It does not drain. Quote Link to comment Share on other sites More sharing options...
johnc Posted October 24, 2011 Share Posted October 24, 2011 FYI... You don't want to recirculate the return fuel to the surge tank. Could cause pressure problems with the FPR if the surge tank pressurizes and it will heat up the fuel over time. Send it back to the fuel tank. The surge tank overflow should go back to the tank and it should be downhill if possible. Quote Link to comment Share on other sites More sharing options...
JSM Posted October 24, 2011 Share Posted October 24, 2011 John, just for clarity then do you run a 3 line Surge tank then and have the return from the Surge tank going to the fuel tank and then a sperate line from the fuel rail going to the fuel tank? Quote Link to comment Share on other sites More sharing options...
johnc Posted October 24, 2011 Share Posted October 24, 2011 I never ran a surge tank - I spend my money on the fuel cell so I don't have to add another point of failure in the fuel system. Quote Link to comment Share on other sites More sharing options...
Cannonball89 Posted October 24, 2011 Share Posted October 24, 2011 I have been running a surge tank with the return from the FPR going into the top of the surge tank with no problems. Johns point about fuel heating may be somewhat true, but with a large low pressure pump feeding the surge tank, I believe that fuel is moving so quickly through the surge tank that it doesn't make a huge difference (after a long drive on the highway or even after a 1/4 mile run the surge tank is still cool to the touch, and it is mounted under the hood too). A surge tank is not like a gas tank, where fuel is sitting and waiting to be sucked in by the fuel pump, it has a very high volume of fuel being pumped through it at a high velocity, making heat soak not much of a factor. In my case I have a 140GPH low pressure pump feeding the surge tank, which feeds a 70GPH high pressure pump that feeds the injectors. That 140GPH pump is moving a lot of fuel through that surge tank every minute. I have never had any issue with pressure on the return side of the FPR creating any spike in fuel pressure, which would show up as a rich spike in the datalogs. It's really just a matter of preference, but I think it is just simpler plumbing to run the return from the injectors into the surge tank (especially if it is mounted under the hood) than to have two separate return lines (one from the FPR and one from the surge tank) running into the gas tank. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 28, 2011 Share Posted October 28, 2011 Most OEM's run the return line through factory surge tanks. If you uncover the main tank pickup under high load, the surge tank will stop getting fuel. Any return fuel coming in could be the difference in running, or running lean. (Boom) The Ford Bronco II has this type of setup. Heating of the fuel is a function of flow through the tank and proper line sizing. There ARE fueling setups that run no return line to the surge tank, but run an FPR on the surge tank on it's return line to hold 3psi in the boost system with an ignition cut on a Hobbs Switch to kill the engine if the pressure drops to less than 1psi. Failsafe. The #75 Cunningham Racing Z32 had 4" diameter surge tanks (TWO of them!!!) fed by two pumps each, and main pump feeding left and right bank (two main pumps, four boost pumps...) The surge tanks were from the roofline, to the skid plate under the car. Almost 42" Tall! They did NOT want to run lean under boost! Quote Link to comment Share on other sites More sharing options...
dpuma8 Posted October 31, 2011 Author Share Posted October 31, 2011 I have 3/8 hard fuel line I will be attempting to put in this weekend. I was planning on putting both feed and return line under my car but if having the surge tank in the engine bay with the return line from the injectors directly to the surge tank is acceptable, then I would rather do that because then I could run one hardline under the car rather than two of them. Or should I still have another line still returning from the surge tank to the gas tank. The car will be stock for now and this is the surge tank I am using except the 1 QT version. http://www.bcbroncos.com/store/advanced_search_result.php?keywords=Accumulator+Fuel+filter&x=0&y=0 Quote Link to comment Share on other sites More sharing options...
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