Extra Injector?

[black_gtst]

is it possable to run an extra injector set-up on the manifold of rb25 instead of upgrading to bigger injectors? if not what are the reasons?

cheers! brett

[BAMR33]

Can be done but it's dodge.

Reasons against:

Uneven fuel distribution to each cylinder

Hard to tune for

Unroadworthy modification

Injector seating issues as there's rail to bolt them into, dangerous if not done properly.

Fuel reversion issues during gear changes when changing gears, extremely dangerous if using atmo BOV.

Looks like puss

[black_gtst]

fair enuff! thought there might be a few reasons againt it. how do they get away with running them on rb30s so sucessfully then? or is it just because they are VL drivers that they harp on about how well they work>?

cheers!

brett

[SECURITY]

there are a few engine management systems that have a setting for an extra injector. im pretty sure the emanage does. how safe this is, i would have no idea on.

[R31Nismoid]

fair enuff! thought there might be a few reasons againt it. how do they get away with running them on rb30s so sucessfully then? or is it just because they are VL drivers that they harp on about how well they work>?

cheers!

brett

It stems from VL racers in the 90's using hobs switches etc, hence they still talk about it as it was common among them back in those times and some still today.

And then it got a little more upmarket with microfuellers to control them.

Usually boost or throttle body position activiated, and then RPM with micro's

Basically to get around the fact no-one wanted to pay for management & injectors but still want some performance increase.

It does work, but in 2007 when management and injectors are so cheap and legals have more issues than ever... why would you bother?

[SECURITY]

another thing thats popped to mind was how they used to compress the tops of their standard fuel pressure regulators to bump up the fuel pressure up by around 15-20psi.

there was a way of doing this by T'ing the FPR to a compressor, run it so it shows the psi then compressing the head of the FPR and you'd actually be able to see what pressure you'd be bumping it up to.

again, im not sure how reliable it would be.

[MANWHORE]

Not only with the vl boganadores. The japs used to use extra injector controllers. I've seen numerous cars with an injector or two in the intake piping.

It's not such a big thing nowadays. With the price of injectors, the hassle isn't worth it for me - looks dodgy. Back in the days, there wasn't such a large range of a/m injectors

[Tangles]

im thinking of dropping in an extra injector (2 actually) thru the stock intake piping

found a used kit in japan includes 2x 700cc sard injectors on the stock rb25det intake pipe

would it be better to flog these 2 injectors off and use 2 stock 5b25det injectors (2 + 6 stock) ?

reason I bring this up, doing some head work last thing to get is the tomei poncams - pretty much a full hiflow rebuilt head with gaskets etc, but stock stnd bottom end.

with the poncams and the headwork Id dare say the stock 6 injectors would be at the 228kw full load mark - hence an extra bit of fuel.

hopeully 2 extra injectors (stock size or the 700cc sards) would allow enough fuel to use the poncams properly

using a remapped ecu chip from Toshi (long distance tune) + safc/sitc + adj.fpr/adj.camgear&poncams + z32afm/full intake-exhaust-cooling mods etc etc,

with the kit Id expect my engine would therefore be tuneable to a point past the 100% load useage mark for 6x stock injectors, instead of being set for a max of say 220rwkw and thats that (without muckn around with new ecu remap chips + bigger injectors), perhaps 240rwkw is possible?

thoughts?

head work includes tomei lifter kit, tomei poncams and oil restrictor gallery, infinity 90mm throttle body with greddy adapter plate, rb25 cometic head / exhaust / intake / collector & manifold gaskets, clear timing belt cover, epp valve seals, valve guides & seats for exhaust/intake, head stud kit, plus the rebuild work by a local shop - including touching up the porting etc

[R31Nismoid]

You'd be better off bumping the rail pressure with a FPR for that kinda of requirement.

Just up the pressure a tad and headroom is found

[Tangles]

got the adjustable Nismo fpr, had that for a few years now, and it gets adjusted with the tunes

mainly looking at this as a way to reach max efficiency for the hiflow turbo (ie 245rwkw), with the head work etc the Stagea should be pretty awesome

can make up a metal box to cover the intake injectors to make it look stock

[SLY-25T]

ive seen a pic of an extra injector or two (i think) on this forum. someone posted the pics up of his mates one. looked dodge but he said its well worth it. ill see if i can find it

[R31Nismoid]

Your maxing injectors with 225rwkw and a increase in rail pressure?

Something doesn't sound quite right there as most people seem to get to around 220rwkw, max em out, add FPR and get 250rwkw give/take

[Tangles]

nps Nismoid. cheers for the info on 250~ for fpr adjustments

havent done it as yet, just gathering info and parts etc at the moment

[Tangles]

showing how NUB I really am - how will the tuners set up control for external injectors?

whats needed to run them, thru a remapped ecu + safc + sitc + adj.FPR ?

Is there a brand name extra injector electronic module available from japan (old-skool, ie ebay/yahoo) that can be bought, installed and setup?

this is the stuff Ive got ready to go:

Cometic intake manifold gasket

Cometic intake collector gasket

Cometic exhaust gasket

Cometic Head gasket 1.2mm x 87mm

ARP head stud kit

EPP 6mm Intake valve seals

EPP 6mm Exhaust valve seals

EPP Intake valve seats

EPP Exhaust valve seats

EPP Intake valve guides

EPP Exhaust valve guides

Q45 90mm throttle body

Greddy Q45-RB25 adapter kit

EPP clear cam gear timing belt cover

Tomei oil gallery restrictor orifice

Tomei hi-lift valve springs ~8.8mm

Tomei 256/256 pon cam shaft set

2x 700cc Sard injector external intake manifold setup

[Adriano]

The problem is that you need to switch the additional injectors on and have the ecu tune change at exactly the same time every time, otherwise you end up with a lean hole or rich spot, neither which is good for the driving pleasure or engine longevity.

[VB-]

you can either use a micro fueler - a separete lil computer to control it, or a hobbs switch - a switch the sees pressure and closes two contacts, think of it as a boost activated relay. some people feed 12V straight to it but another way, which has more risks, but will give a better result, is to take the + off another injector and use that as the feed to the hobbs switch

these are the two common ways, there may be more though

Edited October 16, 2008 by VB-

[Tangles]

cheers, Ive been looking into indepedant fuel injector controllers

will keep on looking into it, get all my info and gear sorted, then hit up the tuners for the head (then see the flow specialist) then back for the head reinstall and tune of everything

[grandmasterb]

I just finished removing the extra injector set up (originally had 2 extra) from my car yesterday. Personally having run it in the past i wouldn't recommend doing it even when set up correctly (mine was part of the GReddy kit) it was a right pain in the arse.

Controlling mine was done with a REBEC 2 and you could set the duty & gain along with the rev range/cut. For an older bit of gear it was ok and did the job but not upto my standards hence getting rid of it all and just running 6x555s instead.

Put it this way, im about to through it all in the bin thats how much i wouldn't recommend it to anyone else or on sell it all