Dysfnctnl85

iTrader: (11)

I can't seem to find a definitive answer anywhere -- what is the proper fuel pump setup for plumbing a surge tank? I've seen some dissension online with respect to using a low pressure pump to feed the surge tank and then a high-performance, high-pressure pump to feed the rails.

I currently have a Walbro 255 external (this is for an FB) and I'm trying to figure out the best approach --

• Purchase a Bosch 044 (for higher HP than the Walbro) and use it to feed the rails, use the Walbro to feed the surge tank
• Purchase an oft-mentioned "Carter" lift pump (I guess typically used in low-pressure carb setups?)
• ??

In addition, what are the technical differences between in-tank and external fuel pumps? Could I just by an internal pump and use it externally, or would this cause a problem with cooling the pump?

I searched the forums but I couldn't really find any definitive answer and I thought this was the best place to post such a question regarding surge tanks. Mods -- please move if this is the wrong place.

Thanks in advance for any advice.

Zero R

iTrader: (1)

Your stock or upgraded in-tank pump(walbro, nippon denso etc) will feed the top of your surge tank, you'll need a good inline pump( something like bosch 044) feeding from the bottom of your surge tank, that will feed the rails. Rails feed the regulator, then the return from the regulator to the top of the surge tank. You could just put the return back to the tank also if the surge tank is large enough.

Dysfnctnl85

iTrader: (11)

In other words, it is safe to use a high-pressure pump to feed the surge tank? Unless I'm mistaken, my Walbro is high-pressure.

Zero R

iTrader: (1)

It will be fine unless you can't make or purchase a quality tank and that shouldn't be too hard.

~S~

Dysfnctnl85

iTrader: (11)

I think (and hope) my tank is good -- I purchased this TweakIt tank awhile ago: http://www.tweakit.net/shop/product_...roducts_id=124.

Thanks for the advice!

arghx

iTrader: (3)

What are you using this car for?

Dysfnctnl85

iTrader: (11)

I don't really have one particular purpose except for surprising people . I would love to take it to the track when it's running.

elwood

iTrader: (1)

1. Decide how much power you will be making and use that to calculate how much fuel flow you will need. Know what your approximate boost level will be.

2. Your pressure pump must be able to provide your calculated fuel flow at your baseline fuel pressure + the boost level you estimated in step 1.

3. Your lift pump must be able to provide your calculated fuel flow at free flow (0 psi).

The good fuel pumps will provide a graph of fuel flow vs. pressure so you can select the correct pump. There's enough experience on the forum to steer you in the right direction, but the free flow rate is easy enough to test -- see how long it takes your lift pump to fill up a bucket of known volume and do the math.

Dysfnctnl85

iTrader: (11)

Wow, lots of info there! Unfortunately I have absolutely no idea what kind of power I'll be making, per se, so I'm just trying to plan to have adequate fuel for my setup listed below in my sig.

I don't think the Walbro will have any problem filling the tank in any amount of time, I was just concerned about high vs low pressure pumps and their application with respect to surge tanks.

Thanks for the advice!

elwood

iTrader: (1)

You really should try to ballpark your power level -- it affects everything in the car: fuel system, ignition system, driveline (especially clutch), etc., etc. The choices you make in these areas will be drastically different between a 200HP car and a 600HP car. With the stuff you have listed, you could be anywhere in that zone.

Once you make a decision, it becomes a bit of a self-fulfilling prophecy. If you design for 400 HP, for example, you'll have to change a whole lot of components if you suddenly decide you want 600.