rb20 injector help

[ISC-Performance]

just wondering if anyone nows what the stock 270cc injectors max out to?? iam looking to get about 250rwkw out of them...is this safe or should i upgrade to 550cc..would rather not tho due to $$...iam also using a fuel pressure reg if this helps

[Maxx]

U should upgrade to 550cc

there is no way i will use stock RB20 , or even rb25 injector and aim for 250rwkw

[Nightcrawler]

I agree with Chapman - in my S15 the 480cc (corrected by Maxx) injectors were running 99% duty cycle at around 185rwkw.

4 x 480cc = 1,920cc 185rwkw

6 x 270cc = 1,620cc theoreticallly = around 155rwkw.

This figure seems wrong with the corrected info from Chapman, but a couple of different places told me I was running very high duy cycle at 185rwkw.

Taking them to 250rwkw is theoretically impossible, and highly unadvisable.

[Maxx]

even worse, our's was 480cc

i will use the fuel pressure reg if 10%, maybe 20% extra flow is all i need

cheap option will the gtr 444cc injector with a resistor box

[sky30]

I had my stock RB20 injectors with a Malpasi regulator running 240rwkw at about 85% duty. I have heard of cars making 260rwkw with the stock injectors maxed out with a regulator. Id say give it a go, you will be surprised.

[ISC-Performance]

what was the setup on your car tho sky30 what computer turbs etc

[sky30]

lunaticR32:- Motor is RB30det, had a Hi-flow turbo making 240rwkw with the stock injectors at 85% duty. ECU is a microtech.

What engine you running?

[ISC-Performance]

rb20det...wouldnt a rb30 have bigger injectors??

[Bl4cK32]

rb30 drops in using all std rb20det gear, including all factory sensors, and injectors. It helps with the setup costs of installing the motor, allowing you to save for bigger upgrades in the meantime

[sky30]

As Darren said, i used the stock RB20 injectors untill i needed to upgrade.

If your target is 250rwkw, i would stick with the stock injectors and spend your money on something else.

[Cubes]

My Rb20DET injectors run 92% making 176rwkw on the stock turbo pushing 9psi.

9psi is due to the better flowing RB25 head thats had a little work done to it + the head is sitting on a rb30 bottom end with big diesel lungs.

Rev it just that little bit more to 5500rpm, power drops and injectors hit 100% duty to try and maintain a flat 12:1 afr.

My external bosch pump is ~3yrs old now, during the holidays i'm going to wire up a dedicated feed from the battery.

[Cubes]

Lunatic.. How long have you owned the car?

It isn't Waynes old car is it?

[FATGTS-R]

Well using the injector flow formula which I learned from this forum:

270cc / 5 = 54bhp x 6 cylinders = 324bhp which equates to around ~195kw at the wheels.

In my situation the formula held up as I reached 187rwkw and needed to upgrade them.

For 250rwkw the 440cc GTR injectors would do the job and not cost the earth at $250-$300.

[sky30]

A malpassi regulator ( or similar) makes a huge difference. With my stock regulator the injexctors did max out at just over 200rwkw, with the malpassi regulator, they made 240rwkw at around 85-90% duty.

Also as joel mentioned, i ran a single power feed off the alternator to the pump, so there isn't so much voltage drop. This also helps.

[Cubes]

sky30,

Its kind of on topic, with the feed from the alt/battery.

May I ask a couple of questions, to help save me some time and research?

Some may seem obvious.

1. Where did you run the wire? Along the main loom in to the car and then splits from the main loom and ran under the carpet to the boot?

2. You took the relays feed from the pumps wire wires?

3. Where did you get 30amp wire and fuse? I've looked at the local auto shops they don't carry 30amp wire and fuse assemblies.

4. Did you use 2 wires (negative & positive) or just the one?

[Sydneykid]

I had my stock RB20 injectors with a Malpasi regulator running 240rwkw at about 85% duty. I have heard of cars making 260rwkw with the stock injectors maxed out with a regulator. Id say give it a go, you will be surprised.

lunaticR32:- Motor is RB30det, had a Hi-flow turbo making 240rwkw with the stock injectors at 85% duty. ECU is a microtech.

245 rwkw = ~400 bhp

At 85% duty cycle that means ~400 cc's per minute of fuel

To get a 270 cc rated injector to flow 400 cc's means an increase in fuel pressure to ~71 psi. That's almost the limit of a Bosch 044 (73.5 psi) leaving no room for boost. The best I have seen was 350 cc's and that was at 55 psi (plus 19 psi for boost = ~73.5 psi). Even then the duty cycle was a bit over 90%, which doesn't leave much for acceleration enrichment or hot day running.

Personally, I am not that keen on running a standard fuel system at 73.5 psi. The standard hoses, fittings and clamps are not realy rated for that sort of pressure. Fuel fires are very ugly. Anyonme going down that route should look at braided fuel fittings all the way from the pump to the fuel pressure regulator.

[Sydneykid]

sky30,

 

Its kind of on topic, with the feed from the alt/battery.

 

May I ask a couple of questions, to help save me some time and research?

Some may seem obvious.

 

1. Where did you run the wire? Along the main loom in to the car and then splits from the main loom and ran under the carpet to the boot?

 

2. You took the relays feed from the pumps wire wires?

 

3. Where did you get 30amp wire and fuse? I've looked at the local auto shops they don't carry 30amp wire and fuse assemblies.

 

4. Did you use 2 wires (negative & positive) or just the one?

I will pop in here, if it's OK;

We always have the battery in the boot (better weight distribution) so it is a short run for both earth and positive. I use the standard pump wire to switch the relay (solid state, I don't like sparking contacts around fuel). I get the relay, wire and fuses from Jaycar or Dick Smith.

[Bl4cK32]

My external bosch pump is ~3yrs old now, during the holidays i'm going to wire up a dedicated feed from the battery.

Cubes, can u have a look at how mine is done...i want a straight feed from the battery with a relay too I think my 044 is using the std wiring atm....

[jvs007]

can sum1 explain this..... i got 205rwkw on my rb20 with 15.5 boost,910 pump, 2530 turbo,dump pipes,exhaust, gtr cooler,pod and remapped ecu. AF ratio was fine. dont know duty cylce, as far as i know standard injectors. i got told many places 180rwkw is maxin out the stock injectors. but others think its ok.

if u max out injectors then u wud start to lean out... is this correct ???

there is so many different opinions with mods these days, dont know who to believe.

[ISC-Performance]

thats why i started the thread iam makin 220 on stock injectors and have been told they can easly make 250....then other people/tuners say no way in hell.....the obvios answer tho is if you want to make over 200rwkw its alot safer to upgrade your injectors etc