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estrada42

280z fuel tank vs Surge tank for EFI/RB swap

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After searching through the archives it seems like most people go with an external surge tank when they do their fuel systems on their 240/260z. Is there a specific reason not to swap in a 280z tank? 

 

I'm in the planning phase for my RB20 swap in my 260z and I was going to put in a surge tank, but I'm going to have to drop my fuel tank any way so I was thinking of just swapping in the 280z tank and not suing a surge tank.

 

Short version is, "Was there a reason you went with a external surge tank over an EFI fuel tank?"

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Was there a reason you went with a external surge tank over an EFI fuel tank?

The answer is simple. The efi tank (and early tanks too for that matter) has zero baffling, making the pickup prone to sucking up air during heavy acceleration, braking or cornering. A surge tank helps alleviate any fuel starvation issues caused by this, and is a great way to protect any high performance motor.

 

Why swap tanks when you've already got to modify the fueling system regardless of what tank you've got? For most it is easier, cheaper and better for performance to just add a surge tank to whatever existing system is in place.

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This is how I solved this problem. Please check out the pictures. I welded a box with baffles. This box is then welded into the stock tank. I can tell you it works perfectly. Even at just 1/2 inch of fuel left in the tank I had no problems. No external surge tank needed.

 

I run a l28et.

 

 

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I'm relocating my battery under my passengers seat and just putting my surge tank, fuel pump, fuel filter and all my lines where the old battery was located.  Then all you have to do is run a feed and return and boom you're done. I was going to put it in the spare wheel compartment but the surge tank I had purchased was too big and I thought it might be cool to have it tucked under the hood.  

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Theres a write up somewhere on the internet, of a fellow taking an FC Rx-7 fuel tank and modifying the rear to fit it. more work for some but fairly straight forwards. Though from what i remember you lose your spare tire well, you gain the benefits of having a fully baffled and EFI ready tank without losing any more room that a surge tank would take up. Just throwing that out there.

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I am running a 280Z efi tank with no problems.

If I may inquire, do you race/track your car? Or primarily city driving?

 

As to Estrada, for most people- I'd strongly suggest a fuel surge tank as well.  it is extremely effective at keeping fuel going to your engine.  Mind you so is fuel-tank baffling, as shown by Xanders rather interesting set up.  BUT adding a surge tank is many, many times easier than either swapping a fuel tank (ie 280z), or taking one and modifying it and welding in your own baffling, or custom fitting another fuel tank from another car that has baffling in it all ready. 

 

Mount the tank, add a fuel pump, run the lines.  Your done.  Should literally take you 1, maaaybe 2 hours if you doddle.   Kits are also relatively cheap off fleabay.  Generic tanks as long as they dont leak are "ok", its just a sealed piece of welded metal thatll never see more than a few psi of fuel-  But you should make sure to run good lines and a "decent" fuel pump that wont konk out.

Edited by Sideways

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I moved my battery to the trunk area. Then installed a surge tank in the battery location. I am running a low pressure pump from the tank that fills the surge tank. Then after the tank a filter and a MSD255 high pressure pump that feeds the fuel rail. After the fuel rail is the FPR that feeds back to the surge tank.

 

Works well so far. Here are some pics

 

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Got a 75Z with rb26 with some mods,about 450hp, Wilwood dynalites, coilovers. 80-90% spirited street some track. Was originally going to add a surge tank, I decided to try it without first. Haven't needed it yet. I am planning to raise it up some to play rally style, maybe rough roads will create issues, don't know yet.

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The answer is simple. The efi tank (and early tanks too for that matter) has zero baffling, making the pickup prone to sucking up air during heavy acceleration, braking or cornering. A surge tank helps alleviate any fuel starvation issues caused by this, and is a great way to protect any high performance motor.

 

Why swap tanks when you've already got to modify the fueling system regardless of what tank you've got? For most it is easier, cheaper and better for performance to just add a surge tank to whatever existing system is in place.

This is the correct answer.

 

The stock tank will work ok as long as tank level is above 1/2. if you get below 1/2 you will start to have issues like described above. Its not the size of the line or the pickup. The stock stuff will support a good amount of HP. The issue is fuel sloshing around below 1/2 tanks and the pickup sucking air. Even if its just for a fraction of a second you will feel it and will more then likely fall on its nose ( I  know from experience)

 

I did a fuel cell in my original setup and it solved the problem. A surge tank will also do the trick. Just because 1 or 2 have not changed and had success doesn't mean you will.

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Just want to point out to anyone that might not know, if this DOES happen to you and you suck up some air, you dont really shouldnt worry about damaging your engine.  Many factory rev limiters work exactly the same way-  "Fuel cut".  Youre not going to run lean- youre not going to run anything, theres no fuel, theres no boom.  However it can be extremely abrupt and very unsettling- Not just for you, but the car.  If this happens mid corner it can be like side stepping off the throttle and then slamming back on it.

Again, fuel surge tank!

A very cheap, very easy to install reserve fuel tank that should be pretty much immune to emptying out due to the amount/duration of G forces youd see durign hard acceleration/braking, and especially cornering. 

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The efi tank (and early tanks too for that matter) has zero baffling,

 

This isn't exactly true. There is a divider in the middle of the tank, starting as early as 1973, and the '75/'76 EFI tanks have a coke can sized shroud around the pickup. But if you're running a high flow pump, it'll suck that dry pretty quick in a sustained hard left turn with less than half a tank of fuel.

 

I have a custom sump welded to the bottom of my tank. If I were doing it again though, I'd go with an in-tank solution. Then you don't have to worry about packaging extra pumps, fuel lines and an added tank. There's also potential fuel heat soak issues. I'm curious if the new Aeromotive Phantom universal in-tank setup would work in a Z...

 

http://aeromotiveinc.com/products-page/stealth-fuel-systems/18689-phantom-200-stealth-fuel-system/

 

Nigel

Edited by Nigel

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I agree with Sideways.  I ran a modified stock tank with internal pump for a while, but it lacked baffling.  Under corning the FPR would cut the power.  Never heard any detonation, but its very unsettling and potentially dangerous to lose power instantly.  I installed the BC Broncos surge tank using the smaller vent line for the return.  The low pressure feed pump makes a low rumble that I don't mind. I am using an external Walbro to feed the rail, that things whines as all Walbro externals do.  Have had some venting issues, but that's my fault because I am using a universal hose for the large vent line instead of ponying up for the pre-formed factory vent line from MSA.  

 

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