Another Rb25 Top Feed Injector Thread

[mynameisdaniel]

I know this has been brought up many times and I've read everything at least twice but there's still information missing. I'm looking to run top feed Bosch EV14 injectors in my RB25 using the standard intake manifold. I have various reasons for this, and yes, I have considered just running Nismo side feeds.

I am aware I need 40 or 48mm (seal to seal) length injectors (are 3/4 length 48 or 55mm?) with 7 or 15mm fuel rail spacers respectively to get it to fit under the plenum.

What I need to know is whether I need 11mm or 14mm diameter bodies (which size are most RB25 fuel rails designed for?) and are adapters required on the manifold side if I want to run these top feed injectors in place of the standard ones?

Any input would be greatly appreciated, particularly similar setups with exact specs.

[r33_racer]

Wouldn't that be determined by the top mount fuel rail you get?

I'm sure you are aware you cant use the side feed rail with top feed injectors.

No adapters are needed for the manifold side. Normally you can use the std injector seal or a standard O ring that normally comes on the injector.

[mynameisdaniel]

Yeah I'm looking at getting a new rail and pressure regulator as well as the injectors. It would, but very few people (even quality brands) actually specify the size of the rail holes so I'm wondering if it's just assumed to be one size or I have to guess...

For the manifold side I don't understand how both 11 or 14mm could fit?

[GTSBoy]

Or you could just call Scotty.

[KiwiRS4T]

^^^what he said. Scot will sort you out with the right rail and injectors to make it work

scotty nm35

[mynameisdaniel]

Thanks guys, I've sent him a message.

The EV14s seem very popular, I'm surprised how little information on them there is..

[Dose Pipe Sutututu]

You'll need 38mm ~ 40mm (o-ring to o-ring) injectors which are commonly known as half height and a 14mm fuel rail. The common half height EV14s I've seen are 2000cc - haven't seen anything less in half height (unless IU can't find them).

On the fuel rail you will need to trim the collars/spacers given to accommodate the injectors.. and in regards to a FPR - you could use the stock one with those EFIHardware adapters OR just go full external FPR.

[n_D]

I have a brand new black r33 proflow rail with 6 alloy length adapters, makes 3/4 length 11mm injectors into full length 14mm to suit the rail. $120 all up if your interested

[mynameisdaniel]

You'll need 38mm ~ 40mm (o-ring to o-ring) injectors which are commonly known as half height and a 14mm fuel rail. The common half height EV14s I've seen are 2000cc - haven't seen anything less in half height (unless IU can't find them).

On the fuel rail you will need to trim the collars/spacers given to accommodate the injectors.. and in regards to a FPR - you could use the stock one with those EFIHardware adapters OR just go full external FPR.

Thanks. I saw the 40mm ones fit well but they're significantly more expensive as far as I can find and my understanding is standard length EV14s (48mm) will just squeeze under the intake manifold with the right rail. Cheers for the tip on the FPR! That'll save some money as I won't need to run more than the standard pressure anyway.

I have a brand new black r33 proflow rail with 6 alloy length adapters, makes 3/4 length 11mm injectors into full length 14mm to suit the rail. $120 all up if your interested

Cheers. If I can confirm this will fit under the standard plenum with 3/4 length injectors (and obviously shortened spacers) I'll send you a PM.

[Dose Pipe Sutututu]

3/4 is a tight fit, you need to relocate shit and also shave some of th plenum down.

1/2 length is tits

[scotty nm35]

1/2 length is tits

But then you need to muck around with cutting the spacers down.

Has anyone actually had any issues with the 3/4 length, or is it all hearsay? I have sold quite a few 3/4 sets with rail kits over the last 6 months and have had no complaints as yet. I really need to get an old 33 manifold and do a trial install for myself, I have only done Neo installs so far.

[Dose Pipe Sutututu]

But then you need to muck around with cutting the spacers down.

Has anyone actually had any issues with the 3/4 length, or is it all hearsay? I have sold quite a few 3/4 sets with rail kits over the last 6 months and have had no complaints as yet. I really need to get an old 33 manifold and do a trial install for myself, I have only done Neo installs so far.

AngryRB had 3/4s - fit but loads of dicking around

[iruvyouskyrine]

Yep, one of the sets you sold to my mate in Newcastle had a lot of problems with fitment, was quite the muck around. This was the stainless 1400cc E85 injectors btw.

(This should not be read as blaming Scotty in any way, we had heard that it would be difficult to fit them and they would just fit under there. Turns out just fits is an understatement on an R33 RB25 plenum)

[AngryRB]

In my case I had a leaking plenum gasket so had to take it off about 5 times, if you didn't have that issue and only had to do this once then its worth it to have some top quality injectors. The vacuum hose underneath between cyl 2 and 3 needs welded up and moved ( brass fitting in pic) and have to shave some material off from under the throttle body, then you have fit the plenum on but its tight still.

The rail I had was a cheap one and I had to shorten the spacers to get the right length but not too hard. Got everything I needed from injectorsonline.com.au , but maybe scotty can do it cheaper for you.

Edited August 21, 2014 by AngryRB

[scotty nm35]

Yep, one of the sets you sold to my mate in Newcastle had a lot of problems with fitment, was quite the muck around. This was the stainless 1400cc E85 injectors btw.

(This should not be read as blaming Scotty in any way, we had heard that it would be difficult to fit them and they would just fit under there. Turns out just fits is an understatement on an R33 RB25 plenum)

All I have been going by is the Proflow and Aeroflow website, they both state 3/4 length injectors are to be used as that is what the kit is to suit. If there are any issues with fitment I need to let them know I guess, but unless someone contacts me I can't help. (without getting a plenum and fitting a kit myself.)

If I can get the length of the standoffs to suit the 1/2 length top feeds I can make them on the lathe and include them in the Aeroflow rail kits. It shouldn't be this hard imo, but everything r33 seems to be that little more difficult.

[1kr33steven]

Ill drop a manifold of next time im in the area scott, Id let ya know bout those 1000's I got of you yesterday but there going in a Freddy mani not stock.

[scotty nm35]

Ill drop a manifold of next time im in the area scott, Id let ya know bout those 1000's I got of you yesterday but there going in a Freddy mani not stock.

Thanks Steve.

[SkudR33]

Deatschwerks offers a wide range of Bosch EV14 top feed injectors with a height of 40mm!

[scotty nm35]

So do Xspurt. There are many sizes available in the half height, that isn't the issue. The problem is no-one has a drop in top feed solution for the 33 gtst, you need to muck around with fittings, spacers etc. If I can work it out I will be able to offer a guaranteed to fit solution for those who aren't willing or unable to modify parts to fit.

[Dose Pipe Sutututu]

So do Xspurt. There are many sizes available in the half height, that isn't the issue. The problem is no-one has a drop in top feed solution for the 33 gtst, you need to muck around with fittings, spacers etc. If I can work it out I will be able to offer a guaranteed to fit solution for those who aren't willing or unable to modify parts to fit.

I already said I would send you all the measurements and parts required

Patience Scotty lol