Fuel injector upgrade question
 

I've been searching and can't find specific enough info for this. I'm doing a motor upgrade and have been trying to see what I need to do for new found power levels.
Basically, I have two 850cc injectors which I was running 360hp on. My power aim with new motor mods is 450hp, everything is setup to take this apart from the secondary injectors which from what I have found I will be wanting to upgrade to 1200cc secondaries at least to run at around 85% duty.

Now when it comes to changing out the injectors, what is involved? From what I have read I may need a new fuel rail? What else does upgrading these involve changing I should know about? Not as easy as "bolt in", I take it.

You can have 850's bored out to 1300, although most of the bored out ones I've seen flow closer to 1500. If you do that, it's plug and play other than needing some kind of EMS that will let you use them. Don't know if it would support that hp level though.

If you go top-feed injector, you'll need a secondary fuel rail and remove the ACV/air pump system. Best option top feed is probably ID 2000 injectors. With those you don't need resistors or an FJO driver. Probably need to fab up some lines or something though. There are a few places out there you should be able to get everything in one kit.

I will look into boring out my injectors, there is somewhere here that may do it, was just reading some horror stories about them though. Have a PFC to run it all.

I already am lacking the air pump system etc so that's fine. So to be a noob, the secondary injectors are the ones on the LIM...right? If I got 1300cc for example, I would need a new fuel rail, Aftermarket FPR and sort out the new lines that would run to them.

What about electrical wise? Do they simply plug in or will that need messing around with also??

Based on your question, it sounds like you have a lot of research to go. There's a lot more involved in delivering fuel than just increasing injector potential output (fuel pump rewire, higher-flowing fuel pump, upgraded fuel lines, upgraded rail, FPR...)

The short answer to your question is that you're going to need at least 850 primaries and 1600 (or even 2000) secondaries and perhaps some alcohol injection.

Here's a good start:

https://www.rx7club.com/showthread.p...ng+case+rotary

The "Search" button is your friend.

Incidentally, I have a pair of 850cc secondaries bored out to 1300cc, which work great. However I doubt you could take 850 secondaries, bore them out to 1500 (nearly twice the OEM spec), and expect reliable fuel delivery.

I realize there is more to fuel delivery than just increasing injectors. I have an uprated fuel pump in.

The main thing I am asking about is what sort of work is required to fit aftermarket injectors with the new fuel rail etc. Thanks for the link, trying to find what I need out of it now, however it is still a very interesting read.

Be good to hear from people running around 450hp and their setups?

^ Bored out 850 injectors will obviously fit back into the stock rail. Think about it, You removed them from the secondary rail.... You should be able to put them back in.

Therefore, You do not need an aftermarket secondary fuel rail, and can use the stock fuel lines.

As far as if the bored out secondarys will be enough fuel for 450 RWHP. What primary injectors do you have? What turbo setup do you have?

Also, I agree you need to do some searching, It seems like you have limited knowledge about the FD fuel system and it would be to your benefit if you understood it better.


John

I know that bored out injectors would go straight back in man, I have just read conflicting stories regarding them.
I have 850cc primarys and a HKS TA45 single turbo.
And yes don't worry I am reading up a shitload on the fuel system. The only knowledge I have of it is from what I saw when I pulled my motor and read over the last week or so.
Perhaps I should look into boring them out more, seems like an incredibly easy option as opposed to changing everything up.

http://rx7.com/cgi-local/3rdgencalc.cgi
^ that's a good fuel calc for FD's

http://www.rceng.com/
rc engineering can bore out your 850's to 1300cc properly and without issues. they also clean, rebuild, and flow test injectors as well.

if you need more then 1300cc for you secondaries, go with a top feed fuel rail (ie kg parts) and go with either the cheaper low-imp. bosch 1680cc injectors and use resistors or an fjo driver. i do suggest id2200 top feed injectors, they are easy to tune and the best injectors you can buy period.

i do not suggest 850's for your primary injectors because of the tuning issues they will create.

You shouldn't need to upgrade your primaries unless you are running some serious hp. Upgrading to 850 primaries requires milling out the stock primary rail and possibly fighting with the idle tune. It can be done, but not really worth it unless you're running stupid power. Why not pop in some ID 2000's and call it a day?

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/installation-image-dynamic-injectors-919715/#post10467907

RC Engineering has a calculator on their website under the "technical notes" section that can help you decide what size you need based on a number of ways of looking at it.

While I don't personally own bored out 1300's, from the few sets I have seen, and from some posts here, the actual flow rates tested were much higher than 1300 (tested by RC and one set by witchhunter).

If you do decide to go with bored out 850's in the secondary position, I'd purchase some new ones and get them converted instead of trusting some modified 15 year old injector.

It all depends on your goals and how much power you want. That will determine where you should start looking.

Just some input on my setup, reiwire fuel pump, 550 primary, brand new (850) bore out to 1300 and Sard FPR on T04 S single setup, and i am seeing 89-92 injector duty cycle in 3rd wot. I just got ID 2000, and Aeromotive pump coming in for winter project.
So in all u may want to consider buying the ID 2000.

I strongly advise against running the bored out 850s. I've have the 5th set fail the other week in 2 years. I am at the point where I'll refuse to work on a car with them. They are absolute junk and I'm sick of fixing them. They all fail. Either they stick shut and blow a motor, or stick open and flood the motor. Any company that continues to offer them knows nothing about injectors. 850s in the primary location cause rich idle and transition issues. Best bet on a budget is to keep the stock primaries and get the FFE fd fuel step up kit which adds a secondary rail, injectors, regulator, and lines.

I wont even tune a car on those bored out 850s. My experience is the same as IRPs. The CJ parts are the best that money can buy : http://www.turbosource.com/mobile/Category.aspx?id=2147

I went with 725pri and 2000cc secondaries.
Any reason you went small on the secondaries when you were already upgrading both sets of rails and injectors? If you ever wanted to make more power or had boost spike or creep you would have more fuel available...

Look here.
RX7.COM Calculators

ID1300s are for E85 or alcohol based fuels( just like ID1700s).

So you should use ID2000s secondaries instead. You can run any combo you want with the Adaptronic.
I have tuned cars on ID2000 primaries even ( both pump and E85) that start/idle/drive just fine with no rich conditions.