Surge Tank Placement

[Marty Rogan]

Hi Guys,

I just picked up a '71 240Z Track car, that is set up for road racing. I have never had a pupose built race car before, so this car has a lot of firsts for me. It is turbo charged for one, with a Megasquirt system, so I need to learn about fuel injection.

I have it at a race shop right now getting a fiber glass front end fitted on it. One of the things the shop owner brought to my attention is that it has a surge tank mounted very close to the rear valance and next to the fuel cell. That could be very dangerous if I get hit from behind or go into a wall backwards. His suggestion was to move the surge tank up under the hood where it would be more protected. Unfortunately his shop deals mostly with vintage racers and he does not have a lot of experience with fuel injection either. My questions is: would moving the surge tank up under the hood be a good place for it? Or is there a reason that it has to be next to the fuel cell?

TIA,

Marty

[preith]

Hi Guys,

I just picked up a '71 240Z Track car, that is set up for road racing. I have never had a pupose built race car before, so this car has a lot of firsts for me. It is turbo charged for one, with a Megasquirt system, so I need to learn about fuel injection.

I have it at a race shop right now getting a fiber glass front end fitted on it. One of the things the shop owner brought to my attention is that it has a surge tank mounted very close to the rear valance and next to the fuel cell. That could be very dangerous if I get hit from behind or go into a wall backwards. His suggestion was to move the surge tank up under the hood where it would be more protected. Unfortunately his shop deals mostly with vintage racers and he does not have a lot of experience with fuel injection either. My questions is: would moving the surge tank up under the hood be a good place for it? Or is there a reason that it has to be next to the fuel cell?

TIA,

Marty

Hi Marty,

IMO the best and safest place for the surge tank is inside the cell, though they aren't cheap. They also sell an internal pump setup too

http://www.hrpworld.com/googlebase.cfm?key=Fuel%20Safe%20Center%20Mount%20Surge%20Tank%20Collectors%20-%20Plastic&form_prod_id=,179,179,179,_4548&action=product

If you have a cell with two fittings (not including the vent) use one of them for the return and plumb it directly to the tank.

[jmortensen]

A surge tank would have return lines back to the cell if external, so putting it up front would require plumbing a couple more lines to the front and back again. I would put it in front of the cell, off to one side or the other so that a hit to the cell wouldn't necessarily mean a hit to the surge tank. The surge tank also doesn't need to be really huge, so if you make it smaller then you're taking less risk. Putting it in the cell is a nice idea, but I think risks can be minimized without the expense just by moving what you have a couple feet forward.

[Marty Rogan]

Thanks for the responses guys. I'll have to see how much usuable space I have further forward. That would keep the cost down by re-using what I already have. Although I will most likely have to re-do the lines. If there is not enough room, or the cost of the braided lines is about the same, I will put it inside the cell.

Thanks again.

Marty

[Marty Rogan]

Another odd thing about the current set up is that it does not seem to have a vent for the tank at all.

[Marty Rogan]

Hi Marty,

IMO the best and safest place for the surge tank is inside the cell, though they aren't cheap. They also sell an internal pump setup too

http://www.hrpworld.com/googlebase.cfm?key=Fuel%20Safe%20Center%20Mount%20Surge%20Tank%20Collectors%20-%20Plastic&form_prod_id=,179,179,179,_4548&action=product

If you have a cell with two fittings (not including the vent) use one of them for the return and plumb it directly to the tank.

I believe the cell does have 2 fittings coming out the top.

So with this set up, would you need 1 pump for the surge, and 1 pump to go forward to the fuel injection?

[preith]

I believe the cell does have 2 fittings coming out the top.

So with this set up, would you need 1 pump for the surge, and 1 pump to go forward to the fuel injection?

No, only 1 pump required total, you need a return bypass regulator and a return line to the cell, which seems to be the norm, I'd venture to guess your car already has this.

A surge tank would have return lines back to the cell if external, so putting it up front would require plumbing a couple more lines to the front and back again

Another reason I prefer the in-tank, simplifies things a bit.

Edited March 26, 2010 by preith

[jmortensen]

With a separate tank you do need a carburetor fuel pump to fill the tank (overflow goes back to the cell). Then you have your FI pump coming out of the tank to the FPR/fuel rail.

If I understand it right the internal surge tank is more like the baffles around an oil pickup than a separate surge tank.

[timurf]

Righto - the internal surge tank is basically the same concept as the trap door affair in the typical competition oil pan. It is a separate plastic container (open at the top) with either one way valves or flaps letting fuel in but not out, the pickup is in the middle at the very bottom.

Therefore the internal surge tank replaces your fuel pickup in the fuel cell, only one line runs between the pickup and the fill plate (which then runs to your fuel pump.)

I have surge tanks in my hillclimber (roadster) and my vintage CP Z. I had problems in certain corners with fuel starvation before using them.

I don't have experience with the external kind - maybe they function like a vent tank?

Edited March 27, 2010 by timurf

[jmortensen]

I don't have experience with the external kind - maybe they function like a vent tank?

The external kind is a can of fuel. Has a carb fuel pump to fill and an overflow at the top which goes back to the fuel cell, and a bung at the bottom for the FI fuel pump.

Here is an article on building one for a 510.

http://www.ratdat.com/?p=168

[Marty Rogan]

I went out to the shop on Saturday to check this out again. With the fuel cell that is in the car, the in-tank surge would not fit. So it looks like I will re-use the surge tank that is there. We found a spot that would move it forward about 12 -18", which should d the trick.

Thanks for the input!

Marty