May need more fuel, change primaries or secondaries?
 

So here's the deal. I'm going to bnr stage 3s and I may need more fuel.

My current fuel setup is 550/1300 on stock rails stock pressure and a supra tt pump. I guess I have a few options. And as a note, I'd like to stay high impedance.

Id725/1300
I heard the Id725 still makes idlig pretty smooth and I'll still be able to pass smog with the right settings?

550/id2000
I heard the transition may be hard to tune because the difference is so huge? But I'll have no idling issues, which is important.

850/1300
Idle is gonna be difficult and I'll never pass smog??

Obviously correct me if my research is wrong. What do you guys think?

I would think your current setup should be good to well over 400 rwhp. How high will you be going?

Why don't you get your turbos, then log some data around your duty cycles and A/F to see whether you need to upgrade?

you need to decided how high you want to go, then see where you are at with the new turbos to see what you need to do. I guess you could spend the money and get bigger to provide for margin of error but you may have all you need already.

I would suggest id2000 secondaries. If you are running a pfc I have a good base map I can send along with the purchase. www.turblown.net/store

Why wouldn't you pass smog with 850's and 1300's? Wouldn't the setup look stock and thus pass a visual inspection?

I've been running this same setup for a year now and have been running 850 primaries for 3 years. I have never had any idle problems what so ever.

Hmm, then what's all this talk about 850 primaries being hard to idle or tune or whatever? I swear people have said this more than once.

850 primaries would be better for a visual inspection but they are a pain in the ass compared to the other options.

i have the same setup and thought about going id1000 primaries.... i also have a brand new top mount rail sitting around. it would be cheaper because id2000's are alot more expensive and you dont have to buy an aftermarket FPR

i'll worry about it when i come to that road

Oh right I forgot. So if I do change out the primaries for a top feed rail then I'll have to get an aftermarket FPR? And if I change out the primary to top feed I won't have to upgrade my FPR right?

Also what is it exactly that makes the 850s a "pain in the ass." Because that seems to be the easiest option.

Ding! Ding! Ding! Winner!


The easiest option is to do what Mahjik said... I'm curious what makes you think that you need to upgrade anyway? What boost level are you looking to hit?


If it makes you feel any better I have 550's with 1300's combo that supplies enough fuel for a GT35R at 15 psi. So if it ain't broke don't fix it :)

exactly, Im reluctant to go 4x 850 injectors purely because many people have said they can never lean out the idle, can any one confirm this ?

Hmmm cool, that sounds pretty reasonable I guess. I was just trying to make sure that when I get tuned, nothing is limiting me. I was looking to run around 16 or 17. Beyond that I need a GM 3 bar sensor?

Pm Rx7_RAGE he sports BNR's and I believe he's got 550's and 1300's


Honestly I think you should purchase a 3 bar sensor. The stock unit reads up until 17 psi so anything past that gets all jacked up. IMO anyone that is boosting above 14 psi should get one, as boost spikes or overboosting on cold weather can easily reach 17 psi when the boost level is to 15+.

Just get the turbo's first. Your probably not going to need more fuel. I had BNR's before and they were fine with the 1300's and I ran up to 17 PSi. And if you just need a little bit of fuel, you can get an FPR and up the fuel pressure.

thewird

Hmm okay. How much power did you squeeze out of them?

I guess I'll get a 3bar map sensor just to be safe, and then re-check my fuel pump voltages.

+1

I run 850/1680 with an FJO injector driver on my PFC and she's smooth as silk.

Depends on the dyno and can range from 330-400 rwhp. Your tuner should decide on where to stop and has nothing to do with any power number.

thewird

For what it's worth, I'm running this setup with the stock twins. I haven't had any problems tuning yet. Injector Dynamics also provides the lag values for you.

If you're going to stick with BNR's, then you should just install them first and then see if you need more fuel, as multiple people have already said. I'm running the 2000's on the stock turbos because I needed more fuel, and I did not want to worry about my fuel system again when I upgrade to a single turbo.

^ I also had zero problems with transition with my ID2000's when I had 650cc primaries before.

thewird

When I installed my 850 primaries 3 years ago all I did was change the PFC settings to what the users recommended on this forum. Even without dyno tuning the car idled perfectly. I don't understand where this whole idea of bad idling comes from.

If it matters I had them cleaned by Witchhunter before I swapped them in and made sure that the O-rings seated perfectly.

I say you just go this route, as it's the cheapest and will give you enough fuel for what you're trying to accomplish with the BNR's. I'm actually in the same group buy as you for BNR's and I will be running this setup, as it's been proven for me running 15psi on stock twins.

Also, why would you waste all the time and money to get a car dyno tuned when there is a risk of running out of fuel. Instead of potentially making two trips to your dyno tuner why don't you just install the bigger injectors now and not have to worry about it come dyno day.

While on subject i see people that use 550 primaries and 1680 secondaries in a single turbo setup, that doesnt have any transition problems?

I also run 850's for primaries and my idle is PERFECT. I should add that I use a Xcessive LIM which has no injector atomizing port for the primaries, I run -.04 lag, 40psi base fuel pressure, I still use the ISC, I adjusted the throttle linkage and throttle body air bleed screw only once to fine tune it. Rock solid in all weather...

If you decide to go with 550/1300 and an aftermarket FPR to bump up pressure, look into the adapter with barb Sard makes for the secondary stock rail. More info-----> https://www.rx7club.com/showthread.p...d+adapter+fuel

Also, not a bad idea to do the fuel pump voltage mod to make sure you have good flow at higher rpm's...

You'll be fine with 550s and 1300s. I'm on the stage 3s as well with bnrs and my injector duty cycle at 15 psi is 80%.

You'll be fine with 550/1300 combo. That is what I run with my 99 seq twins on a street ported motor. Plenty of fuel for 350 rwhp which is what I dyno'ed. Rynberg also hit 350 rwhp on a street ported motor and BNR sequential twins running the 550/1300 combo.