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Radium Auto Fuel Surge Tank write up

Joined
10 August 2010
Messages
633
Wanted to do a write up on my surge tank install and just go over what is needed in case anyone else wanted to install this vs drop the tank and rewire the fuel pump.

Some advantaged of running a surge tank:
1. No need to drop the tank
2. No need to rewire the fuel pump
3. Fuel tank sloshing and lean conditions under cornering are all but eliminated
4. Quick installation and changes in the future
5. Easy to remove and return back to stock
6. Somewhat modular can be setup from 500whp to 800+whp without the need to redo the entire system.

Disadvantages:
1. Price would be high for low horsepower setups, although can save money for high horsepower setups
2. Easiest place for installation requires removal of engine cover(can be mounted in other places that could keep this
3. Adds an additional pump rather than a single point for failure

Parts needed for install:
1 Radium auto surge tank with frame bracket and fully populated harness makes for very easy installation
1 12mm x 1.25 to -6 adapter(fuel filter)
1 -6 straight pushloc hose ends
2 45 degree -6 pushloc hose ends
1 180 or 120 degree -6 pushloc hose end
2 90 degree -6 pushloc hose ends
1 12mm banjo to -6 adapter(forward fuel rail)
2 5/16 to 3/8 barb adapters
1 6 foot section of russel twist lock -6 hose(~4 feet needed for install, I used 3/8 fuel line from advanced auto for my install)
1 section of wire to relay trigger
1 walbro 255 fuel pump

Approximate Cost from Radium auto and Jegs $850 including shipping for the surge tank, pump and all lines/hardware needed. It would be an additional ~$100 for an Aero 340 or Bosch 044.

I mounted the surge tank on the angle bracket(See #1) by the fuel filter as it fit rather well there, and was close to the fuel lines I was modifying. I still need to cut the bracket for a more permanent install this is holding well for now though.

Show below(See #1) is the general routing of the lines. We basically hijack the line going from the fuel filter and route it to the surge tank. I did this by removing banjo bolt going into the fuel filter and replaced with a 12mm x 1.25 to an -6 adapter(See #8). I removed the banjo nut on the fuel rail and replaced it with a 12mm to an -6 banjo(see #5). The walbro 255 inside the surge tank now supplies pressurized fuel to the rail. We also hijacked the return line from the fuel pressure regulator to the surge tank as well. I simply cut the factory return line in half(See #1 bottom left) and used 5/16 to 3/8 adapters as the factory line is 5/16 and my -6 line is 3/8. From the regulator I have the short piece of factory line then a 5/16 to 3/8 adapter and then my -6 hose going back to the surge tank. At the top most fitting on the surge tank I have the line coming out and going to the other end of the factor return hose which returns to the tank. This ensure that as long as the surge tank is full the overflow will go back to the stock tank.

So we have our factory tank keeping the surge tank full, and the surge tank supplying the fuel pressure needed for the motor. 2 Systems working together.

Wiring:

Radium Auto has a fully populated harness which is a great option, It comes with high quality wiring, loom, relay and fuse(See #6). Only 3 Wires need to be hooked up. Power, Ground, and the Relay trigger. Power is had from the engine bay fuse box. Ground can be hooked up to almost any bolt on the engine. I wired up my trigger from the fuel pump resistor box(See #9) This ensures that both pumps only work together or not at all rather than wiring it to accessory. I can't for the life of me find oem 2 pin Honda connectors or would not have cut into the factory part. Fortunately this resistor box is only $45 from the dealer so if i want 100% factory wiring it wouldn't be too bad.

This setup with a walbro 255 is capable of 500+whp, and with a bosch/340 600+whp on gasoline. Using 2 in tank walbro 255 and running seperate lines to each rail would support 800+whp. This would cost a bit more but would be very easy to install.

#1
outline.jpg

#2
IMG_0272.jpg

#3
IMG_0277.jpg

#4
IMG_0279.jpg

#5
IMG_0280.jpg

#6
IMG_0268.jpg

#7
IMG_0270.jpg

#8
IMG_0278.jpg

#9
IMG_0276.jpg
 
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Nice write up. I'd be more interested in a nice trunk mount setup, or rear-bumper area

I'm not a fan of cutting into the trunk, but one could build a nice clean setup with bulkhead fittings. Water tight and less clutter in the engine bay.

I'm building another fuel system still using the surge tank for an 800whp capable setup. Will run the rails in parallel, and aftermarket fuel pressure regulator. I will follow up and post some more pictures and build specs once complete.
 
Whats the surge tank capacity (with the pump in it) and how long will it last at full throttle before starving at 500whp?
The surge tank has a 1.5l capacity. I'm not sure of the exact displacement of the fuel pump off hand.

I don't know the exact flow of the stock fuel pump at 0psi, but the book states the pump should flow a minimum of 119 lph at ~50psi and at only 12v. Conservatively I think 150lph would be realistic at 0psi. Typically I run fuel pump comparisons at 13.2volts which bumps the flow to approximately 165 lph under normal driving conditions. At 500whp the engine would need approximately 185lph. This results in a net loss of 20 liters per hour which equals .33 per minute. This would mean you have approximately 5-6 minutes at 500whp. Under that condition your motor would most likely pop before you ran out of fuel.
 
I was exaggerating but no one sits a full throttle without letting off for 5-6 minutes.

The 185lph is derived from the following calculation:

500whp ~ 575bhp with a 12% reduction from drivetrain losses. 12% is commonly used for a fwd drivetrain like ours, 15 for normal rwd and 20% for awd.

575bph required approximately 57lbs of air per minute which is 3420lbs per hour. This also a commonly use 10lb of air for each 1hp.

With an air fuel ratio of 11.8:1 results in 289 lb / hr of fuel.

I always use 1.58 lb per liter for my fuel calculations. 289lb / 1.58 = 183L/hour.
 
I was exaggerating but no one sits a full throttle without letting off for 5-6 minutes.

The 185lph is derived from the following calculation:

500whp ~ 575bhp with a 12% reduction from drivetrain losses. 12% is commonly used for a fwd drivetrain like ours, 15 for normal rwd and 20% for awd.

575bph required approximately 57lbs of air per minute which is 3420lbs per hour. This also a commonly use 10lb of air for each 1hp.

With an air fuel ratio of 11.8:1 results in 289 lb / hr of fuel.

I always use 1.58 lb per liter for my fuel calculations. 289lb / 1.58 = 183L/hour.

Hi,

I asked a question in another post regarding upgrading the fuel system.

You mentioned you was going to post a thread about running the rails in parallel, how would you do this?

I'm assuming you would come from the filter with a Y fitting and run to each of the banjo fittings that originally linked the two rails?

Would you then purchase like a blank to screw in where the original feed was to the rails?

Or is there a better way? would you flip the rails around or leave them as they are?

It's good to see a parts list for your other mod. Really helps.

thanks :smile:
 
Hi,

I asked a question in another post regarding upgrading the fuel system.

You mentioned you was going to post a thread about running the rails in parallel, how would you do this?

I'm assuming you would come from the filter with a Y fitting and run to each of the banjo fittings that originally linked the two rails?

Would you then purchase like a blank to screw in where the original feed was to the rails?

Or is there a better way? would you flip the rails around or leave them as they are?

It's good to see a parts list for your other mod. Really helps.

thanks :smile:

There were 2 ways I've explored doing this. One with the regulator before the rails in a "return-less" system, and one with the regulator after the rails. The return-less system is the most simple, less fittings and lines, utilized factory rail line. Ultimately I decided not to run the return-less system because I will be at the limits with a single 485 fuel pump and want to make sure the fuel system ensures the best flow. I'm sure the return-less would also work fine as well but safer than sorry. Return-less systems are utilized by the OEM, usually without a 1:1 regulator.

Returnless:
Run the pressure line from the surge tank pump to the regulator
Run 1 return line from the regulator back to the surge tank and 1 line split into a Y into each fuel rail
Front rail utilize the stock banjo
Rear would not enter where the stock regulator was by removing the stock regulator and replace with Fitting from SOS
Keep line by throttle body in tact connecting the 2 rails.

Optimal Method:
Pressure line from pump to a Y feeding each rail
Front rail feed in the stock banjo, rear rail feed would now be where the stock regulator was
Remove factory line connecting both rails and replace with 2 lines going to the fuel pressure regulator
1 more line from the regulator return to the surge tank
 
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There were 2 ways I've explored doing this. One with the regulator before the rails in a "return-less" system, and one with the regulator after the rails. The return-less system is the most simple, less fittings and lines, utilized factory rail line. Ultimately I decided not to run the return-less system because I will be at the limits with a single 485 fuel pump and want to make sure the fuel system ensures the best flow. I'm sure the return-less would also work fine as well but safer than sorry. Return-less systems are utilized by the OEM, usually without a 1:1 regulator.

Returnless:
Run the pressure line from the surge tank pump to the regulator
Run 1 return line from the regulator back to the surge tank and 1 line split into a Y into each fuel rail
Front rail utilize the stock banjo
Rear would not enter where the stock regulator was by removing the stock regulator and replace with Fitting from SOS
Keep line by throttle body in tact connecting the 2 rails.

Optimal Method:
Pressure line from pump to a Y feeding each rail
Front rail feed in the stock banjo, rear rail feed would now be where the stock regulator was
Remove factory line connecting both rails and replace with 2 lines going to the fuel pressure regulator
1 more line from the regulator return to the surge tank

I'm not sure what a surge tank is or does, what are the benefits? I was looking at doing something similar to option 2 without the surge tank.

Would my idea work? leave the FPR where it is. The orig supply on the front rail install a blanking plug and then from the Y splitter from the fuel filter run the lines to both of the banjos on the far left ends on the rails that currently work as the link between the two?

I don't know much about how FPR's work, i know it adjusts the pressure but no idea how it does this. Would this be a issue setting it up like this? because the FPR would only be on the rear bank however they are still joined by the Y piece and part of the same system so you would assume it would work on both?
 
That would "work" but not achieve the benefit you want. The FPR regulates by dumpling to the return line. (If the pressure is too low, it doesn't dump anything.) so you want to minimize the pressure drop upstream of the FPR. You do that by minimizing the distance and flow rate between the injector and FPR. So y into one end of each rail coming in from filter and y out of the other end of each into the FPR.
 
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