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Advise for fuel injector upgrade

8K views 17 replies 6 participants last post by  AKGC 
#1 ·
I'm looking at swapping to e85 and I'm gonna need to work on my fuel system some. From what I've heard 13' fuel injectors are rated at 680cc @ 43.5 psi. But due to the fuel system being non boost reference at max boost the effective fuel pressure is 33 psi. That'd drop the output from 680 to ~592. If I was to swap to a boost reference return style fuel system would the stock injector be ok? If they're 680cc @ 43.5 then at max boost they'd be seeing ~75 psi turning them into ~890cc injectors. So going from the effective stock 592cc to the boost referenced 890cc that's a 50% increase of injector size. And e85 only needs roughly 30% more fuel volume. Is my thinking correct? And sorry for such a long post. Thank you.
 
#4 ·
Which local tuner? Unless that local tuner is TurboXS, BTR, SFR, or Predator you aren't going to get a tune as the ECU is locked and there are only a handful of tuners in the country who can unlock it and tune it. Option B is if you have an aftermarket ECU or a piggy back... but as far as I know, you can't tune E85 on a piggy back... so... yeah.
 
#6 ·
Ah.. okay... as I remember he used to do work for Predator. Anyway... yeah... you need to ask him what injectors you need. The tune will determine how big of an injector you need. If you try to do your own math, you may be purchasing injectors that you can't use.
 
#10 ·
Couple things that hopefully help you understand and rethink.

1) I think the 13+ base fuel pressure is higher than what you are saying. I want to say base pressure is in the 60-80psi range. A quick search should reveal the correct number.

2) Your idea of the boost referenced fuel pressure increasing the effective flow rate of the injectors is not quite right. The idea is to keep the fuel pressure at a constant psi above the manifold pressure. So they won't turn into 890cc injectors. They will stay 680cc injectors over the entire range of MAP.

Hope that helps some. :D
 
#11 ·
You're totally right. I was thinking of it wrong. The effective pressure will stay at whatever I set base pressure to. So instead of the ffectuve dropping to 33 psi it'd stay at the 55 psi. I say 55 psi because that's just what I've heard. Not saying I don't believe you and I will dig deeper into it. So instead if the stock effective 592 cc it'd be 762 cc with it set to a base pressure of 55 psi. I don't think that'd be enough. Thank you for correcting me on that.
 
#12 ·
Right. If you set the 1:1 boost referenced FPR to say 45psi with the vacuum/boost line pulled it will always be 45psi above what's in the manifold. So at 30psi of boost the absolute fuel pressure is 75psi (but still 45psi above MAP so it sprays the same amount of fuel per duty cycle).

I tried to find some info about our base fuel pressure in the 13+ but couldn't immediately find it. I really want to say it's around 80psi returnless. Hopefully someone else can remember for sure.

I'm also going to switch over to E85, but plan to go another very trusted route of ID1000cc injectors with a Haltech ECU. Keeping the returnless setup stock fuel pressure.
 
#15 · (Edited)
Hoping to help and also get some info myself. ALLDATA specifications states fuel pressure is 84psi(at idle)for 2013 2.0. I would usually do a measurement myself to confirm, but I cannot at the moment. Now, the information I am looking for is what the stock fuel injector flow rate is at this pressure? I am also hoping to avoid measuring that myself, but I might just do it. At this point I have only found threads on EVO and 1st gen injectors.
 
#16 ·
Most likely 550cc. I don't see why hyundai would throw in 680cc (in the first post)

Keep in mind that the evo has 550cc and a bigger turbo.


And those that was to switch to e85, I've been told that the injectors need to be rates for e85.


Those that want to switch to a return setup, you will see lower fuel pressures, so you will need to tune accordingly.
The benefit of a return setup is that you can get a fuel pressure regulator with a boost reference, so it maintains or increase pressure higher in the rpms
 
#17 ·
So I did a quick flow test tonight with the stock 2013 injectors. I collected 8oz of fuel for an equivalent of 21 seconds(420 50mS pulses). Check my math but 8oz ~ 237cc, and 237cc * ( (60sec/min) / (21sec) ) = 677cc/min so I'm gonna round up to 680cc. Using the conversion tool on RC Fuel Injector's website, a 680cc/min at 84psi is approximately a 490cc/min at 43.5 psi.

I did not measure the fuel pressure, so this is assuming the stock fuel pressure is in fact 84psi. I also jumped the fuel pump relay manually for the test. I am also assuming the stock pump is not PWM'd or anything like that.
 
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