View Full Version : Walbro 255hp in line of stock fuel pump?(4.2 swap content inside)

Castor Troy
07-28-2010, 01:42 PM
I'm in the process of piecing the parts together I need to swap a 4.2 into my Avant. I plan on going with VEMS, with a wiring harness and ECU from EFI Express, as well as EFI Express fuel rails, and a fuelab fuel pressure regulator.

My plan for fuel is to replace the stock fuel filter with a Walbro 255HP and a -8an fuel filter with replaceable element, with -8 up to the fuel rail, and -6 out of the FPR for the return line (will obviously have to convert it back from AN to the stock style line for the return, or put a -6 return in the top of the bucket, which is also possible...)

Going this route is my plan because I have all of these parts already (except for the EFIExpress rails) from a different project that got scrapped. Is the free flow rate of the stock fuel pump going to be enough to feed the Walbro and support an eventually ~500hp?

1.8T is coming out next weekend, getting ready for this:

http://sphotos.ak.fbcdn.net/hphotos-ak-ash1/hs341.ash1/29229_10100229309119620_13917242_62036568_17978_n. jpg
http://sphotos.ak.fbcdn.net/hphotos-ak-snc3/hs352.snc3/29229_10100229306819230_13917242_62036461_3932609_ n.jpg

07-28-2010, 03:36 PM
You don't need to make all those changes to the fuel lines to support the MAYBE 300whp you'll get out of the 4.2. A simple walbro in-tank with stock lines will easily support your needs with that engine. Hell I'm running a HTA30r at 30lbs of boost running e85 and I'm STILL okay with the stock lines.

How exactly do you plan on squeezing 500hp out of that thing?

Castor Troy
07-28-2010, 04:23 PM
rear mounted turbo :)

07-28-2010, 04:32 PM
remote turbos are insane and sound awesome without a muffler.

07-28-2010, 04:40 PM
Make sure that you start a VERY detailed thread in the Projects & Builds section when the time comes :) . I love these V8 swaps.......and if you can squeeze a lot of power out of it, you'll have the best build out there, IMO.

Good luck man.

Also, about the fueling....From what I've read, I believe the Walboro 255hp is good for power levels up to 500whp, which is generally good for most builds. If your goals are to push 500whp, why not go for an 044? Its not that much more money (for an inline option), and you can handle upwards of 700hp

Castor Troy
07-28-2010, 05:06 PM
As i said, my reasoning is this: i already have the inline 255hp, as well as all the plumbing and fittings I would need to put the 255hp in line of the stock pump. if i can make that work as opposed having to try and sell the stuff I have and purchase parts to go a different route, I'd much rather make what I have work.

According to the fuel pump testing that AMS performance did, at 60PSI(iirc the ABZ runs 4bar/58.8PSI stock), a single 255HP external will do 257 liters per hour, and dual inline will do 300lph. I assume the stock A4 pump feeding a 255HP would do somewhere in the middle of those two, which would be more than enough for my needs...