TimZ Posted November 23, 2011 Share Posted November 23, 2011 (edited) Hi All... I've been struggling with fuel starvation issues for the majority of the summer this year and after inspecting/upgrading/replacing everything else, I bit the bullet and revisited my stock modified fuel tank. When I converted to E85 I eventually changed over to a very high capacity pump and the stock fuel pickup would no longer suffice. My original plan was to tap into the existing swirl pot inside the tank and use a larger ID pipe (0.75"id as I recall) to connect it to a weld-on rear sump pickup (sorry, I don't have any pics of the old setup). To deal with the E85, I had a local internally coat the tank with an alcohol resistant coating. This worked fine for a year or so, but started to have issues this year. The new plan has been to remove the stock swirl pot and plumbing and replace it with a much larger one that could keep my pump fed. I settled on a 7'x7"x10" stainless steel box that I would slide into the bottom of the tank: ...this should give me a ~2 gallon head of fuel to keep the pump fed - MUCH larger than the stock piece. I added two 1/2" NPT female fittings to the bottom of the box to feed the two -10 hoses to the pump. In order to keep the box filled with fuel I took a two-pronged approach. First, the stock swirlpot uses a jet pump fed by the return line to transfer fuel from the tank and keep the pot full (here's the Wiki on Jet pumps). I wanted to also use this approach, so I fabbed a much larger injector pump from a series of fittings: ...the black fittings on the left are tapered inlet -10 male to -12 ORB tapered fuel fittings, the tee is a -12 ORB tee, and the stainless bits are to adapt a 3/8"id Swagelok fitting for the new 3/8" stainless internal return line. I drilled out the Swagelok fitting to allow the 3/8" stainless line to protrude into the tee: As a backup I fabbed a trap door inlet from a modified stainless piano hinge: Here's how it all fits together inside the tank: After removing the old soldered-on rear sump, I had to cut a square hole in the bottom of the tank to accomodate the box, in the location of the stock swirlpot. I removed the swirlpot and associated plumbing, and cut and drilled out the stock outlet and return lines. I replaced the outlet line with a stainless 3/8"NPT female coupling to accomodate the new return line: I cut two 4" access holes in the top of the tank to allow me to get to everything inside and see what was going on. I found a pair of bolt rings for fuel cell inlets that I could use to cap these holes off when I was done. I then spent HOURS AND HOURS removing the old internal coating everywhere and cleaning up the inside of the tank. I used Permatex liquid rust converter (tested it first by submerging a test piece in E85 for 24 hours with no ill effects) to do a first coating of the inside of the tank. After this cured, I used Caswell two-part epoxy to completely coat the inside of the tank with an alcohol-proof coating, leaving an inch or two from the edge of the big square hole for the stainless "box", in order to allow welding it in later. this allowed much better access to all the nooks and crannies inside the tank while coating it. After welding the box in, I finished the epoxy coating around its edges through the two access holes, and plumbed in the jet pump and return line fittings: I'm happy to report that I've got this all back into my car and it appears to be working flawlessly! Here's a couple of final pics of it installed: Edited November 23, 2011 by TimZ Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted November 23, 2011 Share Posted November 23, 2011 As always Tim... nice job. Tell me, is there a way to calculate how much fluid fuel you use at any given boost / RPM / HP? Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 23, 2011 Share Posted November 23, 2011 That's some nice work. Thanks for taking time to post up the details. I'm pondering something similiar and you've given me some great ideas. jt Quote Link to comment Share on other sites More sharing options...
ZT-R Posted November 23, 2011 Share Posted November 23, 2011 As always Tim... nice job. Tell me, is there a way to calculate how much fluid fuel you use at any given boost / RPM / HP? What if you put a fuel flow meter on your feed and another one on your return, then do the math? I guess you could calculate it on the duty cycle of your injectors and pressure and figure out how much cfm it is? If not there is always the interstate 5 miles at WOT then fill the tank back to full, lol. Quote Link to comment Share on other sites More sharing options...
TimZ Posted November 23, 2011 Author Share Posted November 23, 2011 As always Tim... nice job. Tell me, is there a way to calculate how much fluid fuel you use at any given boost / RPM / HP? Sure - the quick and dirty way to get the fuel consumption rate at any given point in a datalog would be to divide the injector duty cycle by 100%, then multiply by your injector's flow rate and then by the number of injectors. If you want to know how much fuel that equates to over a period of time you would multiply that number by the time interval in question (the more accurate method would be to go sample by sample and add up the results). This functionality is built into the latest release of the toolkit, btw... Quote Link to comment Share on other sites More sharing options...
BlueStag Posted November 26, 2011 Share Posted November 26, 2011 Tim, Excuse me if I am a bit dense here, but: Why was all this necessary? Have you transplanted a ZX turbo into an early Z, meaning that the gas tank is just not designed to provide a rapid enough delivery of fuel to the injectors? I ask because my long-term ambition for my Triumph Stag which currently runs a carburated Z engine with a 2.8 Turbo. I'll need to look into the question of how the fuel system will need to be adapted. It might be the largest issue to tackle when I get there. Quote Link to comment Share on other sites More sharing options...
TimZ Posted November 27, 2011 Author Share Posted November 27, 2011 Tim, Excuse me if I am a bit dense here, but: Why was all this necessary? Have you transplanted a ZX turbo into an early Z, meaning that the gas tank is just not designed to provide a rapid enough delivery of fuel to the injectors? I ask because my long-term ambition for my Triumph Stag which currently runs a carburated Z engine with a 2.8 Turbo. I'll need to look into the question of how the fuel system will need to be adapted. It might be the largest issue to tackle when I get there. For a zx turbo engine making 300-400hp, the stock 280Z tank should be fine. My application requires significantly more than that - my fuel pump flows 230 gallons/hr, so it needs to be able to draw that amount from the tank without causing a vacuum in the feed line and cavitating. Quote Link to comment Share on other sites More sharing options...
BlueStag Posted November 27, 2011 Share Posted November 27, 2011 For a zx turbo engine making 300-400hp, the stock 280Z tank should be fine. My application requires significantly more than that - my fuel pump flows 230 gallons/hr, so it needs to be able to draw that amount from the tank without causing a vacuum in the feed line and cavitating. Holy hat. I'll be happy enough with about 200 hp. Quote Link to comment Share on other sites More sharing options...
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