4x4dave

There are like 4 variations of walbro 255's you can buy. That appears to be the right pump. You definitely want the GSS342, but not sure what the difference is between a GSS342 & GSS342s but it either way it won't plug right in without the 400-1048 installation kit. The lightning has a much larger plug on the fuel hat, the NA trucks have a tiny plug which connects to the fuel pump. This is why you need the adapter / install kit. Don't get the GSS340 either, It did not fit properly in my fuel hat since the intake portion was too wide. Below is a picture for reference, note how large the inlet is on the GSS340. If you get the install kit you get the adapter wire which allows you to plug the pump right in without splicing wires etc...



Btw here is the exact pump i bought, it's supporting 380RWHP with some extra elbow room. This is the only place i know of that sells the install kit to make it a true plug n' play deal. Plus it's free shipping...

http://www.ebay.com/itm/REAL-Walbro-255LPH-High-Pressure-Flow-Intank-Fuel-Pump-/320670462473?pt=Motors_Car_Truck_Parts_Accessories&hash=item4aa972f209&vxp=mtr

MyFX4Project

So I just buy that fuel pump and with the kit that comes with it will allow me to hook it into my fuel hat?

Sounds good to me. Now i need to find injectors.

4x4dave

Yep that's it! Have you considered going larger than 24# hr? It would suck getting tuned for 24s and later have to buy larger injectors plus do another tune again.

jferg92

How will 42s run NA?

MyFX4Project

Is it going to hurt me to go larger? Stock is 19# and im not running boost. Just intake tune exhaust really. Slightly larger cams and higher compression. Thought 24# would suffice..

ibd2328

iTrader: (2)

If you are planning to see 320hp at the flywheel or so, 24# with a 80% duty cycle with a BSFC of .45 -.5 would be good. I haven't read the specifics and % on the pressure above 40-50 psi.

If you are assuming to make around 350 or so, I would go up to 42#'s. They are easy to fine and you can never go wrong with larger injectors. Just make sure you get high impedance ones 11-16 ohms will work with the factory PCM. Low impedance ones will require a driver.

The 80% duty cycle will give you a little safety net if you begin to start running lean. Even at 350hp and 80% duty you would mathematically need around a 27# injector assuming PSI is 45.

The only draw back is a little worse mileage with the 42's. Miliseconds count when your nearly doubling your injector size. With a great tune, you could limit this and have lots of room to grow. Just remember those are over double the factory size, so with the same pulse(opening and closing) over twice the amount of fuel will go into the chambers, killing your good idle and mileage without a great tune. You will be running really rich if you don't get a good tune. Sorry for the redundancy in my response.

ibd2328

iTrader: (2)

Nothing wrong with larger injectors, espiecally if you get a tune. Your pulse widths may be a tad bit off causing harsh idles and harder to crank. However, I don't think you would have issues with 24 or 42's. If you get a tune you can run pretty much anything. Or go all out and get a FAST EMS system. I'm running 79# and 3 255's with my own custom fuel hat and lines. Just used some submersible hose, 3/8" barb fittings to connect to 7/16 SS lines that combine into a 3/4" SS line then into a -8 AN fitting. Return line is 3/4" SS from the bottom of the tank with a -6 an bulkhead at the top.

You can mount and wire them however you want. I have 6 gauge wire running to the pumps on 3 heavy duty 40amp relays. Just need some SS hose clamps to hold the pumps in place.

Fore makes a great fuel hat, but im not paying 1200 bucks for a hat, lines and pumps when I can make my own for 300.

ibd2328

iTrader: (2)

Your CR should be around 9.8 assumin a 3.552 bore, flat tops, and a deck clearance of .120

I went with 38CC heads and -17cc 3.572 bore. I'll be running 18-20 # on over 9.5 CR

MyFX4Project

There you go again talking all these fancy numbers confusing me lol

I honestly have no idea what kind of numbers this thing will make. Ill probably just stick with 24lb and after I slap it on the dyno and see what it does ill readjust accordingly.

Having a hard time finding 24# injectors for our trucks though.

4x4dave

I thought this was useful, it explains everything to properly determine your fuel injector size in laymans terms. I'm no injector expert either, but this helped ALOT!


If your shooting for around ~320RWHP on a N/A engine then the equitation came to 28.57, so call it 29#hr to 32#hr depending on pricing availability and all that junk. Get ones in ev1 style connectors (assuming 2v & 4v use same style fuel injector connectors) or you can use adapters. That would easily support 320RWHP @ around 70% duty cycle. I'm guessing that's close to your HP goals, plus you get some flexibility for adding more power later down the road, along with the safety of the injectors not being at max duty cycle.

Just thinking for down the road this will save you $$ and you wont have to upgrade your injectors and re-tune for larger ones. 42# would probably be overkill, and 24# seem a bit small with very little flexibility on fueling for more mods down the road, although im sure you could still run them.