Big pump setup...return line -6 or -8?

[Firechaser]

My last and final decesion on this system...Changed my plan a bit, now went with a Weldon 2035A Pump w/ controller...one of robbmc's billet hat's w/ -10 lines to run the external. Will be dual-fed into the Champ rails w/ -10 and.....that's where I want some feedback.

Option 1 : -6 return w/ Aeromotive's 13101 dual fed reg

Option 2 : -8 return w/ Weldon's A2040 dual fed reg

My "mentor" :biggrin: (pacecarta) who I trust bigtime is very confident in -6, I am just being overly-concerned as this pump has the capability to move alot of volume....so, taking the chance of questioning my buddy...I gotta ask My concern stems from the fact this car will see a good amount of "cruise" nights/street time in the summer too and I want no fuel heating or cavitation prob's w/ the big pump.

 

[GNVYUS 1]

Well with the Weldon you definitely have the volume and the pump noise to keep the Ricers away.

The Aero 13101 has a -10 outlet, the chart mentions that and a -6 outlet fitting which can be confusing. When in doubt just go -8 return and get a -10 to -8 anodized or SS reducer fitting and be worry free. :biggrin:

I'd keep an eye on the Aluminum rails, I had the white pixie dust in mine and would anodize them while they're off the car.

 

[TurboTnZ06]

Just go -8 for the return., the controller is why you could get away with -6 I think if it slows the pump down for low volume needs. The RobbMc hat is anodized. I have the -10 in/out one too I also added 45* adapters as they suggested in the instructions to clear the tank.

If you run Aeroquip TFE line, it is thinner overall (easier to install) compared to a rubber lined hose.

Here's my setup:

 

[Mathias]

I have -8 hard lines and -8 hoses on the ends for my supply and return. I pump from fuel tank to engine bay regulator to fuel tank mounted in OEM position.
I collected fuel from the pumps thru a 3 ft -8 hose and a MagnaFuel 9433 regulator set at 10 psi at 3.1 gallon per minute . I collected fuel from the return line after it passed from the pumps thru an engine bay mounted MagnaFuel 9433 regulator set at 10 psi and had 3.1 gallon per minute.
My conlusion was that there was very little pressure loss due line size/configuration with my -8 lines. My -8 line should handle 3 gallon per minute of gasoline or alky for a carburated engine. For a higher pressure system, FI, the -8 lines would not affect the regulated pressure by restricting the return flow.

 

[49-blues]

Where are you guys mounting your pumps with the Robb mc performance large sender-I'm also considering running 10an supply and 8 an return lines. Thinking of mounting my pump in the spare wheel well opening in the trunk for easy access.

 

[TurboTnZ06]

Where are you guys mounting your pumps with the Robb mc performance large sender-I'm also considering running 10an supply and 8 an return lines. Thinking of mounting my pump in the spare wheel well opening in the trunk for easy access.

I'm going to mount my pump in an S shape with two filters where the factory crossflow muffler would have been.

 

[49-blues]

No concern of losing pump prime at that height?

 

[Firechaser]

Mounting mine very similar to turbotnZO6...on the inside bumper support, I got a Weldon so not to worried about prime.

 

[TurboTnZ06]

No concern of losing pump prime at that height?

From weldon's site on the 1100:

"Self Priming
- Pump may be mounted above fuel cell
vertical or horizontal mount"

 

[Hot Air]

-10 supply, -8 return. Do it once and do it right!
Hot Air

 

[tom j]

Everybody says a -6 wont work. It worked just fine on mine. I ran a weldon 2035 with no controller and could run my f/p down to 25psi, this was on a single fed fuel rail.

 

[Mathias]

The pump pressure/flow capacity, the engine power, and induction method are the factors to consider in selecting a fuel system.
A 1/2" supply and return will handle 3 gpm with adequate pump(s) and no sharp bends or other obvious restrictions. If the pump(s) will supply 3 gpm at 25 psi, you can expect about 3 gpm back to the tank. That is more hp than you will be making. Size your pump(s) accordingly.
Also, an importantly overlooked item is the hose construction. The old standard inner liners are going to start degrading almost immediately with some fuels. Is your hose becoming resistent in bending movements? The material degrades and gets in the fuel flow. The current recommendation for long term use is teflon inner liners, which will last for years.

 

[Firechaser]

I'm running all teflon lined hose already as a feed and going to run the same as the new return....One interesting point I heard regarding return size is the -6 sizing could actually help on a hard launch w/ keeping fuel pressure
in-check versus the -8. Good to hear from Tom as he has actually used this pump.

 

[Mathias]

About 1994, I was asked about the inertia of the fuel in the supply/return lines starving the injectors. After calculating the effects and then simulating in a lab setting, forget about that. As a practical matter, the launch has to be over 1.2 G's and the lines have to be on the launch axis, on and on to have a measurable change.
The practical side is more affected by the reaction time of the regulator, the location of the regulator and the pressure/flow characteristics of the pump.
A -8 line will have about 2 times the fuel per inch as a -6 line. If there is a starvation condition, low pressure at the injectors, review the above.
We use pressure transducers to measure fuel pressure at the injector log. Typically, we see no more difference at launch than during the run. See Cal about getting one and use the FAST or another system to measure the pressure accurately. Then you will know if the fuel system is a problem.

 

[Firechaser]

About 1994, I was asked about the inertia of the fuel in the supply/return lines starving the injectors. After calculating the effects and then simulating in a lab setting, forget about that. As a practical matter, the launch has to be over 1.2 G's and the lines have to be on the launch axis, on and on to have a measurable change.

Wow...OK then :biggrin: I ain't smart enough to rebutt that one so I am just gonna agree and roll with it :smile: