A/m Injectors Into Rb25

[BEN 0]

I was just in the diy section and couldn find much.

i would like to know if any one has fitted direct fit side feed injectors of larger the stock capacity into their rb25det?

what i was wondering could this be done at home?

is it possible to get at injectors without removing top of plenum?

thought i have heard the job is risky has any one had prolems?

also i have a power fc now i'd have to work out the new flow rate so it can adjusted has anyone done this the driven there car to a workshop for a tune?

any light on this type of subject would be very helpfull

[BEN 0]

some ones gotta have some insight?

[Kaido_RR]

hey Ben,

Many jap-brands sell direct-fit injectors for rb25det, i just bought some NISMO 740cc injectors which are direct fit.

I went to fit them today, and found the job abit complex, but the looks of it there are 4 nuts on the underside of the plenum which will need some-sort of tool which can bend into that place.

Once those 4nuts on the bottomside are remove it looks like you just have to plugs the hose etc and then remove the fuel rail and replace the injectors (i was advise its best to take the fuel-rail off the car which changing the injectors)

Im going to give to another go 2morrow, and see if i can find a tool which will undo those bolts

Cheers Michael

Ps i was quote by a local workshop $300 to change the injectors

[BH_SLO32]

I recently fitted some Nismo 555cc injectors to my RB25. Initial attempts to undo the fuel rail bolts without removing anything proved fruitless and I found it was MUCH easier once I removed the throttle body. Access to the fuel rail bolt below the throttle body and the fuel injector plugs is much better.

A word of caution, once the fuel rail is free and the injectors are clear, be careful not to hit the end of the fuel injectors on any hard objects as the pintel caps break easily (as I discovered with injector 6). Obviously the same applies when installing the new injectors.

I think you will struggle to slide the fuel rail out the front of the engine if the throttle body is in place. Incidentally I am assuming the motor is in the car.

Removing the injectors from the fuel rail is easiest done by placing 2 flat head screwdrivers in the slot on either side of the injector and carefully leveraging against something placed under the screwdrivers.

Once the injectors are installed (with new O-rings!) you can re-install the fuel rail. I recommend buying a new metal gasket for the throttle body (about $30 from Nissan).

Hope this helps.

Cheers

Edited February 4, 2006 by BH_SLO32

[R31Nismoid]

Make sure you get Nismo.

Sard are not a direct fit without collars and will give you a headache trying to make em fit.

Nismo - way-to-go

[Kaido_RR]

I recently fitted some Nismo 555cc injectors to my RB25. Initial attempts to undo the fuel rail bolts without removing anything proved fruitless and I found it was MUCH easier once I removed the throttle body. Access to the fuel rail bolt below the throttle body and the fuel injector plugs is much better.

<{POST_SNAPBACK}>

so you didnt remove the plenum at all? just took the Throttle body off then you were able to remove the fuel rail?

im going to give this a shot 2morrow

[grigor]

Not all that hard, just finniky. You don't need to split or remove the plenum, just the throttle body and the AAC valve assembly.

But be very careful you don't lose the insulating washers between the fuel rail and the manifold. They sit in a machined groove and are easy to dislodge.

Before you start, clean the area and give it a good blow with compressed air and be extra careful nothing drops in the open manifold once the rail is out.

Take the opportunity to replace that impossible to get at fuel hose at the rear of the rail.

There is probably some tool to remove the injectors from the rail but having nothing like that, I installed longer injector retaining studs then popped each one out using compressed air. The plastic collets on the pintle valves are super fragile.

New nitrile "O" rings and it all goes back OK.

Dial in your new duty cycle in the PFC. In my case using Nismo 555's the ratio is 370/555=67%, I used 70% and the lag time is the same as Nissan so that's good.

It will then run perfectly for your trip to the dyno.

Thanks to SK for the injector info.

[BH_SLO32]

so you didnt remove the plenum at all? just took the Throttle body off then you were able to remove the fuel rail?

im going to give this a shot 2morrow

<{POST_SNAPBACK}>

That is correct, throttle body only. Grigor also raised some good points especially about the insulating washers, don't drop them or you could be searching for them for a while.

Cheers

[BEN 0]

grigar: when you tuned your new duty cycle on power fc did you go to settings inj duty and the change all injectors to 70%

[grigor]

From memory it's Settings then Inj.

You should see the 6-injector duty cycle and lag times.

Go down each one and alter the duty cycle accordingly.

For the Nismo 555's I used 70%

The 67% maths presumes your old injectors were actually good for 370cc's. They may have been doing more or less, but it will drive to the dyno very nicely at 70%

[abcent]

when i replaced mine i took the top half of the plenium off...that was by far the longest part of the job. Its a bit fidely, but straight forward, should be able to get it done in less than a day, took me a few hours plus drink & food stops....lol. Take the advice above an should be pretty right, nothing more i can really add. Old injectors are quite brittle, so take care removing em if you plan to keep or sell em. I broke 2 oops..

good luck

[BEN 0]

like me just clarify cause i need to drive 4 hours to preferred tuner

what looks to be easiest remove top half plenum

carefully replace injectors

now to the confusing part

im using 600cc so 370/600=0.62(rounded up)

does this mean i change all my inj duties to 62% in my pfc