Jump to content
SAU Community

Recommended Posts

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

Link to comment
https://www.sau.com.au/forums/topic/104170-am-injectors-into-rb25/
Share on other sites

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 :rolleyes:

Cheers Michael :D

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

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 by 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.

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 :D

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.

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 :P

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

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%

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

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

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I came here to note that is a zener diode too base on the info there. Based on that, I'd also be suspicious that replacing it, and it's likely to do the same. A lot of use cases will see it used as either voltage protection, or to create a cheap but relatively stable fixed voltage supply. That would mean it has seen more voltage than it should, and has gone into voltage melt down. If there is something else in the circuit dumping out higher than it should voltages, that needs to be found too. It's quite likely they're trying to use the Zener to limit the voltage that is hitting through to the transistor beside it, so what ever goes to the zener is likely a signal, and they're using the transistor in that circuit to amplify it. Especially as it seems they've also got a capacitor across the zener. Looks like there is meant to be something "noisy" to that zener, and what ever it was, had a melt down. Looking at that picture, it also looks like there's some solder joints that really need redoing, and it might be worth having the whole board properly inspected.  Unfortunately, without being able to stick a multimeter on it, and start tracing it all out, I'm pretty much at a loss now to help. I don't even believe I have a climate control board from an R33 around here to pull apart and see if any of the circuit appears similar to give some ideas.
    • Nah - but you won't find anything on dismantling the seats in any such thing anyway.
    • Could be. Could also be that they sit around broken more. To be fair, you almost never see one driving around. I see more R chassis GTRs than the Renault ones.
    • Yeah. Nah. This is why I said My bold for my double emphasis. We're not talking about cars tuned to the edge of det here. We're talking about normal cars. Flame propagation speed and the amount of energy required to ignite the fuel are not significant factors when running at 1500-4000 rpm, and medium to light loads, like nearly every car on the road (except twin cab utes which are driven at 6k and 100% load all the time). There is no shortage of ignition energy available in any petrol engine. If there was, we'd all be in deep shit. The calorific value, on a volume basis, is significantly different, between 98 and 91, and that turns up immediately in consumption numbers. You can see the signal easily if you control for the other variables well enough, and/or collect enough stats. As to not seeing any benefit - we had a couple of EF and EL Falcons in the company fleet back in the late 90s and early 2000s. The EEC IV ECU in those things was particularly good at adding in timing as soon as knock headroom improved, which typically came from putting in some 95 or 98. The responsiveness and power improved noticeably, and the fuel consumption dropped considerably, just from going to 95. Less delta from there to 98 - almost not noticeable, compared to the big differences seen between 91 and 95. Way back in the day, when supermarkets first started selling fuel from their own stations, I did thousands of km in FNQ in a small Toyota. I can't remember if it was a Starlet or an early Yaris. Anyway - the supermarket servos were bringing in cheap fuel from Indonesia, and the other servos were still using locally refined gear. The fuel consumption was typically at least 5%, often as much as 8% worse on the Indo shit, presumably because they had a lot more oxygenated component in the brew, and were probably barely meeting the octane spec. Around the same time or maybe a bit later (like 25 years ago), I could tell the difference between Shell 98 and BP 98, and typically preferred to only use Shell then because the Skyline ran so much better on it. Years later I found the realtionship between them had swapped, as a consequence of yet more refinery closures. So I've only used BP 98 since. Although, I must say that I could not fault the odd tank of United 98 that I've run. It's probably the same stuff. It is also very important to remember that these findings are often dependent on region. With most of the refineries in Oz now dead, there's less variability in local stuff, and he majority of our fuels are not even refined here any more anyway. It probably depends more on which SE Asian refinery is currently cheapest to operate.
    • You don't have an R34 service manual for the body do you? Have found plenty for the engine and drivetrain but nothing else
×
×
  • Create New...