Factory Rb20 Injector Limit

[r3240sx]

I have a garrett journal bearring t3. It *might* be a super 60 but I'm not sure about that.

.60 AR Compressor housing

.48 AR exhaust housing.

Garrett claims 350 hp on they're current t3 with a .42 AR compressor housing.

I'm just curious, as I broke a plastic tip off of one of my 450cc injectors, what sort of boost should I run with this new turbo on the factory injectors? I have an SAFC, HKS EVC, and will be using an AEM wideband.

At this maximum safe boost level, what horsepower should I be making? My goal is 300 whp, but I figure that might be pushing it too far.

Thanks!

-Max

[r3240sx]

I figure this turbo I have might be comparable to a high flow in size, any comments? I'm pretty unsure of what sort of numbers I should see at what boost levels with this thing...

[-_-StRyDeR-_-]

iv been told 18psi is max for standard injectors (with standard FPR). 18psi is when they start to lean out.

but can someone else confirm this??

[R31Nismoid]

Its dependant on airflow

Its not a "given" psi. One turbo might will flow more than another, etc etc.

So using "18 psi" is a load of rubbish

Depends on the car/turbo spec and carry on from there

cheers

[-_-StRyDeR-_-]

o ok, does adding a FPR help the injectors out a bit?? (some say yes, others say no)

CJ

[r3240sx]

Its dependant on airflow

Its not a "given" psi. One turbo might will flow more than another, etc etc.

So using "18 psi" is a load of rubbish

Depends on the car/turbo spec and carry on from there

cheers

This is why I listed the specs on my turbo, and injectors...

I'm not looking for an exact answer, but just a safe guestimate..

Thanks!

[45ULT]

with my t3/t4 turbo i got 327hp with stock injectors and a cheap FPR. Injectors reached 100% just before redline and a/f's went to around 12.7-13:1 can't quite remember.. the turbo has a .63 exhaust and a .5 or .55 front again can't remember. this was with an safcII aswell. And also 18psi

[r3240sx]

Good to know, I dont want to reach quite that high of a duty cycle, but I also have a smaller turbo than you...

I'll keep the boost around 16 psi and maybe take my fuel pressure up a few PSI.

Thanks for the response!

PS: do you have a dyno graph? and did you add fuel with your SAFC?

[45ULT]

yeah got a dyno graph i'll scan it and put it up. but it only have power against boost, no af. we actually had to take out fuel over most of the map as the factory computers just dump the fuel in as a safety measure. we tried addiing more fuel at the top but it didn't help which is how we know its the injectors. set ur fuel reg to 40psi as the base pressure. i ended up turning mine down to about 15-16psi on high boost for the street just to be safe

[Cubes]

45ULT,

So you run only 40psi base and managed 327rwhp?

[45ULT]

yep thats what i got told to set it to by the guy who tuned it.

Edited July 8, 2007 by 45ULT

[r3240sx]

thats with the vacuum line unplugged correct?

[Adriano]

thats with the vacuum line unplugged correct?

My guess is that this is with idle vacuum, and a rising rate reg.

Seriously, i dont see why you guys dont spend the $200 and upgrade to gtr injectors, its a small % of what you are spending doing it up, and than skimping on the most important part

[CEF11E]

I have a lot of difficulty believing rb20 injectors can flow enough for 327rwhp. regardless of rail pressure. also you do not want to run a rail pressure of any higher thn 60 psi due to o rings and hoses that are 15 years old (44 psi + 16psi boost) even if you did run 4 psi extra rail pressure that is less than 6% more fuel and 270cc equates to 273.5 horsepower at the flywheel then add 6% and you get 289.9 horsepower at the fly wheel at 12:1 afr.

then you have drivetrain loss to consider:)

I am not trying to start an argument but there are the calculations for you.

to keep it simple, 200rwkw is the maximum i would want to run on RB20 injectors!

[1400r]

I'd run 230rwkw max and have with stock fuel pressure 10.1 afr using a walbro pump

as have many of my friends

at the end of the day stick it on a dyno with the stock inj in place and see how you go

[Adriano]

I'd run 230rwkw max and have with stock fuel pressure 10.1 afr using a walbro pump

as have many of my friends

at the end of the day stick it on a dyno with the stock inj in place and see how you go

Why would you run 10.1 AFR?

[Cubes]

On Boostworxs dyno myself and a mates both hit 100% duty at around 180rwkw with a 12:1 afr and stock fuel pressure.

Mate of mine was running a suspected GTR pump that later ran out of fuel at 250rwkw and my own which is a bosch 044.

180rwkw is 241rwhp so 29rwhp drive train loss going by the usual 270cc injectors = 270hp. :S

Maybe our beloved DD Dynos are reading a touch high as technically its not possible for 270cc injectors to make 241rwhp when you consider drive train loss.

[Adriano]

On Boostworxs dyno myself and a mates both hit 100% duty at around 180rwkw with a 12:1 afr and stock fuel pressure.

Mate of mine was running a suspected GTR pump that later ran out of fuel at 250rwkw and my own which is a bosch 044.

Was the 250rwkw with stock injectors with a stock FPR?

[1400r]

lol wouldnt run 10.1 if I had a choice

but with a fcd as the only ecu mod meant I didnt have much choice

[Cubes]

Was the 250rwkw with stock injectors with a stock FPR?

Sorry no. His stock injectors with the same fuel pump and stock fuel reg hit 100% duty at ~183rwkw with 12:1 afr's Gt35r .82 on 7-8psi.

Dropped in a set of sard 800 twin sprays maxed out the fuel pump at 250rwkw and then went on to make 260rwkw on 1 bar.

The turbo really didn't make all that good power under 10psi; over 10psi it really woke up.