Mackers

Upto what bhp are the standard STI 8 injectors good for (not at 100% duty)

Also what size are they?

Doing a few upgrades soon!!

Dave.

scoobytyson

Think they are 565cc and good for around 400bhp

Mr Footlong

iTrader: (7)

AndyForrestPerformance - Fuelling

Look at the bottom of Andy's page, it may or may not be relevent to your model .

SSCJAY

You will struggle to make 400 bhp with standard fuel pressure, more realistic figure is 360-370 at 90 ish percent duty cycle.

Mackers

I'm fitting a Fuel Lab Regulator will this help achieve a higher BHP figure and duty cycle percentage or just ensure an even fuel flow?

Cheers lads

Area 52 Autosport

STi pinks are just over 500cc. If you run higher base pressure then yes, you can reduce duty cycle (obviously within reason)

dynamix

iTrader: (3)

Will they be Pinks in this or the Blue Top 505's ?

SKS

They'll be pinks on that model - 500cc.

Cheers,

Stewart.

dynamix

iTrader: (3)

When did they start putting blue tops in STI's then?

Henrik

iTrader: (5)

hang on, i thought new-age sti injectors were 565?

Turbotits

iTrader: (2)

Thats what i thought and have been told tooooooo

SSCJAY

yes Pinks are around 565 cc, The 505cc blue tops were first used in Hawkeye .

AndrewC

I thought they were 552.xx (where xx varies between ECU variants)

Std injectors are good for around 370bhp at std fuel pressure, 420ish at 4bar.

What turbo are you fitting?

Henrik

iTrader: (5)

Ah cool, thanks for clearing that up

Mackers

One of Andy F's TD05 20G

Area 52 Autosport

OEM "pink" injectors are 510cc per min. Straight from the STi parts book and verified by both tuning test limit results on all the ones we've used over the past 6 years since the New Age was launched and through our injector flow test rig.


A common mistake made by a lot or retailers though that they are perceicved to be bigger than they actually are.

Someone else has mentioned above that they thought 370BHP was their limit, I would suggest that is fairly close unless you're going to "run the nuts" off them (not advisable).

If you're likely to get to that kind of HP, you really do need the next size up (650cc) to retain a little headroom on IDC's.

AndrewC

Mike, I know that hence the smiley - you'll be telling me that WRX injectors aren't 420cc next

Dave, The fuellab FPR at 4bar will be fine for a 20G.

Andrew...

Mackers

Fine for 400bhp?

Thanks Andrew.

dynamix

iTrader: (3)

a good rule of thumb for injector sizing is:

injectors size / 1.375 = max bhp

=>

505 / 1.375 = 367
650 / 1.375 = 472

etc etc

Mackers

Excellent!! If this is true it should be entered into a ScoobyNet hall of teccy fame or something.
But what about adding to the formulae for considering fuel pressure

Can anyone put a fruit pastel in the mouth and not chew it while solving that one

dynamix

iTrader: (3)

This came from Pat the Map so is true enough for me