Ocelot

Whats the general consensus on the subject? I've heard of some running with all 4 fine, then others that are saying its bad. Anyone have actual EXPERIENCE with them running bad, or is it all myth spread around with no actual source? Can anything go wrong with installing all 4? BTW I've got a BNR Stage II that I plan on running up to 14psi in the future, a RB turboback and an a'pexi intake if it matters.

TurboIIRyan

installing 4 makes it easier to tune by. And then you don't have to detune the hell out of them when they come on as secondaries.

powrdby13B

only problem with all 4 720's is decreased gas mileage.

DerangedHermit

What kind of fuel management do you have? If you have a standalone then the 4x720's would probably be your safest bet. Don't want to run outta gas. Then again, I don't know how much you'll be needing (not a turbo guy).

TurboIIRyan

If you don't rune somesort of fuel controller. Grab yourself an SAFC2 and utilize the 2 maps you can run. Run a low throttle gas saving map for anything under full throttle, then a high throttle map for anything WOT.

Ocelot

I've got an S-AFC, my concern with not running all 4 would be like high gears at WOT where boost builds up at low rpms and stays on for longer.

powrdby13B

your concerned with the integrity of the motor then?
have you rebuilt? how many miles?

Aaron Cake

iTrader: (1)

If you are running them directly on the stock ECU, then this will be a problem. But if you have an S-AFC or a full standalone, the size of the injector won't have an effect on mileage (unless you get really large, or are constantly driving in boost) if they are properly tuned.

gsracer

Get all 4, I ran them on the safc before and now I run them on the e-manage just fine. You'll need the fuel.

Matt

RETed

If you run large fuel injectors in the primaries, the stock ECU has a tendency to flood at cranking.
I hope you have a fuel pump cut-out switch.
No, this doesn't matter if you have an S-AFC.
In my experience, this is a 50% chance the engine will flood when the engine is already hot; it very rarely floods when cold starting.
I run a Field SFC-HyperR + 4x720's on a G-Force reprogrammed ECU.


-Ted

gsracer

I've never had the engine flood when hot, however this could be an issue on much older/tired engines. I've never run a compression test on the current issue, as of now it's at 78k miles.

RETed

My engine all brand new seals and o-rings with about 30,000 miles on it so far.
There is no way that you can adjust for the initial cranking primer short of reprogramming the ECU to do so.
This is why the car tends to flood with the larger primaries.



-Ted

ShadowX

So the RTek is likely not going to fix this either? (Except for having the "Flood Clearing" option"

Parastie

Meh, the rx7 engines are prone to flooding anyways.

With your list of mods i'd go with the 4 720s and install a fuel cut switch.

The Griffin

Since you have an S5 , you don't need to worry about a fuel cut switch.On the S5 just mash the go-pedal to the floor, this will envoke the fuel-cut function built into the S5 if you have a flooding issue.

usmcjsy

iTrader: (1)

Ya go with all 4 720s I have the stage 3 BNR and that what I run.

WallyHojo

This is for usmcjsy or if anyone else can answer this. With 4x720cc injectors do you have to add resistors to them? I herd the ECU can fry after a while using bigger injectors?

kd86rx7

iTrader: (1)

i have only 720cc secondaries, with rtek, and safc2 soon. soon putting on a t04b v trim turbo with a mild port motor.

eric.

NZConvertible

No, it won't.

It's not the size of the injectors that matters, it's their impedance. Low-impedance injectors must have resistors when used with the stock ECU. However most injectors bigger than stock are low-impedance, so you will usually need them.

SureShot

Check the "super AFC" forum.
There's a thread on using the pressure sensor signal into the throttle position feed of the S-AFC.

I wired it that way so full throttle at low boost dosen't waste gas, and part throttle in cold air & mid revs dosen't lean out.

If your 550's are in good shape thay are fine as primarys.
Any doubts can be checked with a wideband..