Surge Tank Location, Installation and Design
 

where a good spot to put a surge tank in a s4 rx7 im also going to run a 500hp external pump with it. anyone got any idea's or pics

thanx
madaz

Are you going to do sanctioned racing with it?
If you do, there are strict rules about running your fuel system inside the vehicle.


-Ted

its just going to be for the street and some 1/4 mile work just looking for the best place to put it and a way to get around that fuel smell ya get with it??

If you run on an NHRA track, their rules are sealed baffle with minimum 0.040" aluminum (or equivalent) for ANY fuel components running inside the "cockpit".

If done correctly, you're not supposed to smell ANY gasoline inside the vehicle.  Gas smell inside the vehicle means fuel leak!


-Ted

do you know any spots to mount it???

Okay, retarded question of the week:

How do you plumb a surge tank in the fuel system?

you have a big tank and a surge tank.... a smaller fuel pump feeds the surge tank from the big tank. The surge tank has an overflow tube that replaces the return line and goes back to the big tank... the bottom of the surge tank has a line going out to a much bigger fuel pump, which is capable of feeding high amounts of fuel to the rails. The return line goes back into the surge tank.

I believe that I've seen people mount them under the car as well. You don't have to mount the surge tank in the car if you don't want to. Someone correct me if I'm wrong here.

Zach

Convert to a single exhaust and install the surge tank in place of the 2nd muffler.

and if someone hits you in the rear???? BOOOOOM

Here's a pic of the surge tank on my car. It's roughly 3" round and 18" deep.

-Destin

Because the stock fuel tank isn't located in the rear, right?

Think about it a little... :) The stock tank is protected a little by the spare tire well, so if you feel uncomfortable with the surge tank (a relatively small tank compared to the large main tank) located right at the rear bumper, you can install a few inches of foam between it and the bumper. Just like the stock tank is set up. Clearly, if you are using this setup, you're not going to want to pick a surge tank that would fill all the available space. You need a few inches on each side (and probably 5-6" at the back) of buffer space. The stock main fuel tank is set up in the same way.

Also, it is amazingly difficult to ignite fuel during a collision. Not saying that it's impossible, but I would be quite a bit more worried about the 60 litres of fuel in the main tank then the few liters of fuel in the surge tank if the collision was severe enough to rupture a tank.

I am thinking I am going to put my surge tank where the stock fuel filter goes (under the brake booster) and mount my external pump and filter on the frame rail in front of it (and below it).

I won't have to find a place under or in the car and fuel line routing is EASY as you can use the stock lines for fuel in and out of the surge tank and short funs of the big AN stuff to the pump and from the regulator. Wiring the pump is easy here too as it is right near the + term and I might just use those unused stock EFI relays.

What problems do you guys see with this?

I think it is further from the hot exhaust than anywhere under the car I could fit it and less chance of fuel in the cabin than if it were in there.

Convert to a single exhaust and install the surge tank in place of the 2nd muffler.

:) That is where I had my alum battery box when I had a single exhaust system. Now it is in the dr. side storage bin- it is dry cell type anyways...

I don't think it will fit. There's hardly any space near the fuel filter. Well, it might fit, but it will be tight. Running hose and fittings could be a pain.

So if I wanted to build up a surge tank for my car then I could stay with my Walbro 255lph pump in the main tank and then run a stronger fuel pump in between the surge tank and my fuel rail. Am I on the right track here? It sounds like that would be cheaper in the long run than buying a custom dual Walbro 255lph in tank setup. Especially since I can do all of the metal work myself.

Zach

Generally you want a high volume low pressure pump to feed the surge tank. Since part of the purpose of the surge tank is to keep air bubbles out of the high pressure side, you don't want a high pressure pump churning it up.

Then what size pump are you talking about for the main tank? I just mentioned the Walbro since I already have it installed. Thanks for the advice/info Aaron, it is greatly appreciated.

Zach

The Walbro is a 255LPH pump as I recall, so you need one that will flow slightly more then that. It should be a low pressure type pump.

Any suggestions? I was thinking along the lines of using the Walbro 255 pump in the main tank and then something along the lines of an Aeromotive A1000 after the surge tank. I only know flow rates, I don't know anything about a low pressure pump so any info would help me out quite a bit.

Zach

I don't think it will fit. There's hardly any space near the fuel filter. Well, it might fit, but it will be tight. Running hose and fittings could be a pain.

From what I measured I can fit a 4" dia 10" long surge tank there with no problems.

Any suggestions? I was thinking along the lines of using the Walbro 255 pump in the main tank and then something along the lines of an Aeromotive A1000 after the surge tank. I only know flow rates, I don't know anything about a low pressure pump so any info would help me out quite a bit.

This is exactly the same parts I am working with. Walbro in tank, A1000 pump and its filter.

Once the fuel pressure is off the intank pump it can flow obscene amounts of fuel to supply the 2ndary pump that has to deal with the flow at fuel rail pressures.

According to my calculations... that surge tank would only be a little over a half gallon.... arent they supposed to be a little bigger?

I don't know why it would need to be bigger.

As far as I understand it the surge tank funtions as a reserve of fuel for the 2ndary pump when the primary in tank pump is starved for fuel at its pick up- such as during high G corner.

If you are getting 5 MPG at wide open throttle that would last for 2.5 miles of NO fuel being picked up at the tank wouldn't it? That is a long strange shaped corner to be able to keep the Gs up and still apex it.

Hmm, lapping a skidpad too many times consecutively has caused cars to lose oil at the pan pick up and fuel at the tank pick up so this might do it. There is no way you would be anywhere near wide open on a skidpad so maybe 16mpg or 8 miles of skidpad before there are problems?

I dunno, but I would be more worried about my oil pump pick up or passing out from dizziness and wrecking :P

The intank pump before the surge tank doesn't have to be as big as the inline pump after the surge tank. You plumb the return from the engine back into the surge tank and then an out from there back to the main tank. Also most surge tanks aern't more than 2 liters or so.

-Destin

So from what everyone is saying the my combo of a Walbro 255lph in tank pump with an Aeromotive A1000 after the surge tank would work just fine? I do think that this will be a better solution for me instead of running a custom dual pump in tank setup.

Zach