Fuel Injector concerns, selection questions
 

So long story short, I picked up a single turbo FD project a year ago and I'm having second thoughts about its current fuel injectors. Here's the basics on the setup, as I got the car, and as it stands now:

- New Mazda 13B-REW short block crate motor, no porting or internal mods done to it other than the E-shaft oil thermal pellet mod. Added a Banzai oil pan stiffener kit to prevent leaks & Banzai oil pedestal for the oil pressure & temp taps I wanted.
- 13B-RE Cosmo LIM & UIM, with GM DBW throttle body & TB adapter.
- Turbo is a Borg Warner s364.5 SX-E with 1.0 AR turbine housing, Turblown welded exhaust manifold, dual Turbosmart Comp 40 waste gates with open dump tubes.
- Exhaust is a custom fabricated 3" all the way back setup that the PO built; basically straight back to a large oval muffler with dual tips. Too damned loud & obnoxious for me, so it will eventually be replaced with something like the RB or Tanabe catback, a resonated mid-pipe section (vs. straight thru pipe), and then mod the existing 3" DP as required to mate it all together.
- Cooling: Koyo N-flow radiator in OEM mount configuration; dual OEM R1/R2 oil coolers with OEM ducts; Intercooler is a XSPower larger than stock size core in a SMIC configuration, with a custom made IC ducting to supply it with fresh air.
- Ignition: 4x AEM IGN-1A smart coils, direct fire mode, Magnacore wires.
- Engine management is via a Link G4+ Fury
- Fuel pump is currently a OEM FD pump, but rewired for full voltage. Plan to replace it with a Denso Supra TT or Walbro pump in the near future.

As for the current fuel injectors, I shipped them out recently for cleaning/flow testing, and to confirm what I inherited from the PO. Attached is the report I got back from the shop that serviced them for reference. The primaries are Bosch part # 0280158040, which are EV14 1000cc FIs with the extended tips. In the secondaries, I've got a pair of Bosch #0280158821, which are 2000cc NG12 injectors which are really designed for CNG (compressed natural gas). Hence my biggest concern - I've read that these CNG injectors tend to gum up internally and flow significantly less than spec when used with pump gas, which is really E10 in most parts of the USA. The before/after static flow test results seem to confirm this as these injectors are only about a year or so old, and covered less than 800 miles between myself and the PO.

I'm also not too happy with the before/after results on the primaries, given the % change in such a short time, so I will probably go with all new injectors - goal is a consistent tune, so I'm thinking of getting a set of ID's to do the job. Question is, what would be the best injector sizing & primary/secondary ratio to shoot for in this case? ID currently offers injectors sized at 1050, 1300, 1700 and 2600cc.

If I went with ID 1300XDS as primaries, and ID 1700XDS secondaries, I should have sufficient fuel for my needs as I'll run pump gas (E10) have no interest in running E85. What I don't know is will the ID 1300XDS primaries be able to support a smooth idle? The current Bosch primaries idle smoothly at a 3~4% duty cycle - the 1300's would require a shorter DC/shorter pulse width to do the same; would I still be in the linear operating range of the 1300's to make that possible? So at maybe 2~3% DC?

Another option is to use ID 1050 primaries, and ID2600 secondaries - this solves the potential smooth idle problem, and has way more fuel headroom than I'll need, but the ID 2600's are spendy and not always readily available. If I went with ID1050 primaries, and 1700 secondaries, would that still be enough fuel for a pump gas only setup? I should also mention that I'm not shooting for big dyno numbers here; this will be a sub-400RWHP motor with boost limited to no more than 15psi.

Wayyyyyyyyy overthinking this. For your situation, this is a game of connect 4 and not chess. For your power goal, you could use stock 550 and id2000 if you wanted. You dont need much fuel to get what you're looking to get and still have plenty of room up top. 1000/1700 will be more than enough for what you need. Definitely change that fuel pump immediately. I'll never understand why people do all those engine upgrades and dont touch the pump.

Also, you'll be able to get a very smooth and stable idle with the 1000 primary.

Yeah the fuel pump is on my "do ASAP" list. My FC is running an AEM Infinity ECU with a square ID 1000 setup in all 4 holes (primary/secondary); it idles great with the ID 1000 primaries and based on DC data in the logs, there's plenty of fuel headroom for that setup. It dyno's at about 370RWHP at a 15psi boost limit with a BNR stage 3 turbo. Though my power goals for the FD are similar to the FC, the FD's BW 364SX-E turbo can push significantly more air at any given boost pressure as compared to the BNR in my FC, and more air typically means more fuel is required. I'll have to double check the number crunching, but I suspect a 1000pri/1700sec setup will be enough.

ID1300cc in the primaries will idle smooth with no over rich conditions etc on pump gas.

https://turbosource.com/blogs/news/r...r-pump-gas-e85

Good on you for keeping up on injector maintenance! My stock injectors running with .5oz of premix needed cleaning every two years on the dot. Top feed ev14s are much nicer to mess with as far as maintenance goes. IDs use a stainless body, but that still doesn't guarantee gumming up won't happen as the problem is the fuel/oil. The ID1050s are great, but they don't even try to get any atomization out of them. The tip is just a massive hole and it shoots out like a fire hose unlike unmodified ev14s that are made to atomize fuel properly. Even with running 15afrs at cruise, at a base pressure of 43psi, you won't get a complete burn and you'll occasionally pop flames on decel.

With all that said, the 1050 does idle and operate nice and linearly and I would highly recommend them paired with the 1700s for your power goal. 2200s will work as secondaries as well.

No matter what you go with, you should always keep up on injector maintenance with these cars. A little bit for a cleaning saves a lot for a rebuild.

^Thanks, that link was very informative! Confirms an ID 1050/1700 pri/sec setup will be perfect for my needs.

Didn't know that the ID 1050s spray like a fire hose; I suppose they did that because lots of motorsports tuners that use them tend to run higher fuel rail pressures, where atomization is less of an issue. I'm running a typical 43.5psi base fuel pressure, so I might just retain my newly serviced EV14 1000's for the primaries, and put some new ID 1700s in the secondaries. That will save me some coin that I can put to replacing the fuel pump instead - these cars are money pits.

Yeah, I learned the hard way about injector maintenance shortly after I picked up my S5T2 some 20+ years ago and was a lot dumber. Hadn't gotten around to servicing them yet, they were probably never touched by the PO's and the car had about 89K miles on it - that motor puked an apex seal a month after I got it. Happened on a hot day, climbing an uphill freeway ramp, A/C on and in 3rd gear - right around 4000RPMs where the secondaries should have been opening up more and contributing to fueling, which they obviously weren't. Discovered that after I shipped out the OEM injectors to get them cleaned/flow tested before using them in my new motor, and the before/after static flow results confirmed the secondaries were severely clogged up before.