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Fuel injectors and Pump

17K views 9 replies 7 participants last post by  RoboTuner 
#1 ·
Hello, sorta new to this page. Just been reading so far. Sorry for the newb post, but I'd like a couple answers. I'm thinking about getting injectors and a pump. I'm not 100% on the difference between pumps and what is good for my car (09wrx), and what size injectors I need and what will fit with a fuel pump. Don't be too harsh. Just like to know the basics about buying and picking what stuff I need. Thank you.
 
#3 ·
@Fidrat, Ive got that bookmarked on 2 computers now. I might distill it for travs a bit here.

The things to look for in fuel pumps are their flow rate, compatibility with factory fuel sending units/tanks, reputation for longevity, and in very extreme cases their amperage draw. Depending on the type of build you are looking into you will want a fuel pump that can dump an appropriate amount of fuel into the system to keep yourself from running lean. To that same end fuel injectors with an increased capacity will take that extra fuel flow from the pump and dump fuel into the engine feeding that need for fuel. As you increase the amount of boost ( extra air in the engine ) you need to increase fuel flow to keep the mixture on the rich side of Stoich so you dont start pre-burning, detonating, or knocking.

The exact fuel pump and injectors you need is dependent on the amount of boost you intend to run. On a stock engine with a stock turbo the most common fuel pump upgrade is a walbro 255lph pump, they are relatively inexpensive and they can handle enough fuel flow to feed 450 Crank HP on the EJ255 ( Not that the rings and bearings handle it particularly well but the fuel pump feeds enough that you dont go lean ). Lots of other brands make fuel pumps as well and most can be run on the factory wiring harness. If you plan on doing any heavy duty tuning or you plan on swapping for a larger turbo you might also consider a fuel pump that is can run E85. E85 fuel pumps tend to be a bit more expensive but they dont corrode when exposed to E85. E85 is less prone to knock and lets tuners push the limits of boost beyone what 91 or 93 octane fuel can deliver.

As for injectors 750CC is about as high as most people want to go with their stock engines. They have more than enough flow to keep your engine from running lean and most of them work with your stock fuel rails. Again if you intend to build the engine out or you intend to replace the stock turbo with a larger one then you will want to discuss injectors with the tuner doing to work for you but as a safe baseline 725 or 750cc injectors should work great with your stock setup ( assuming you get a proper tune for them )

hope that helps
 
#4 ·
I was wondering about this topic as well. I plan on doing a 16g swap for the faster bearing and running slightly larger injector so I know that I have plenty of fuel. Along with the 16g would be full exhaust a few intake mods/, and a turbo wrap.
 
#5 · (Edited)
if you want to run E85, 1000cc and walbro255 at minimum. anything lower and your injectors will be running close to 100% duty, which isnt good. you want some headroom. lower might "work" but wont be as safe. most high-end aftermarket injectors & pumps are all E85 compliant these days, but doesnt hurt to double check the product youre buying. Injector Dynamics, DeatschWerks, & Walbro products all work with E85 and those are usually the go-to brands for fueling.

if you wish to learn more about E85:
 
#7 ·
well, as of my last tune, i am running at 271bhp, with and intake and stage1 tune. i would like to push my car at or over 300bhp, or close to it. injectors seem to be my next option, out of many, that are relatively easy to do. i dont have alot of upgrades, except for short throw, light weight crank pulley, intake, and AP tune.
 
#8 ·
@TravsWRX If your looking to make up the difference between 271 and 300 you might want to look into a stage 2 setup with E85. Swapping out the restrictive stock down pipe with a high flow CATed pipe will free up some extra boost. An E85 sensor/pump/injectors could deliver more fuel and a proper tune could net you a considerable increase in power.
 
#10 ·
I second arcticsythe about getting a turbo back exhaust. Also stay away from DW injectors, many shops won't even tune a car with them because they flow different from each other injectors and sometimes have different spray patterns (BAD). Stick to FIC or ID injectors as they don't have these issues and support e85. Read the Phatbotti thread as well as Unibombers manifesto to get a better understanding about these parts how they work together.
 
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