injector size?

**Edward-T** · 07-12-2011, 02:24 AM

if i go with texas speed prc stage 2.5 heads which size injectors should i use?

**SSwt00SS** · 07-13-2011, 06:46 AM

first, what other mods do you have? you don't necessarily upgrade injectors on a head only swap. your stockers would be enough. you are either 26 or 28 lb/hr stock.

you will need to have the duty cycle checked out to determine whether or not you need injectors after the head install and tune. if your stockers flow 90% or higher in duty cycle its recommended that you go to larger injectors. 36lb/hr would suffice, but if you plan on doing major modding, go ahead and get 42lb/hr injectors and call it a day.

**Edward-T** · 07-13-2011, 07:00 AM

423 horse power and 396 FT. LB. Torque
2005 LQ4 6.0 -64000 Miles at the moment
6-speed Tremic transmission
-Everything down has less than 5000 miles
Texas speed Torquer V.2 Camshaft 595/598 lift 112 LBS
Texas speed chromemoly pushrods
Comp Cams Gold Double Beehive vavle springs good to a 660 lift
Hedman Headers-
Headman offroad Y-pipe
Single Chamber Flowmaster Catback exaust
4.10 Ring and pinion
Eaton Positraction unit
Spec stage 3 clutch (cevlar material)
Race performer flywheel
GM Heavy duty slave and clutch master cylinder
Walboro Race 90 psi 255lph fuel pump
New oil pump
Professional DYNO tuned, tuned by JR Racing in Greenville South Carolina.
---
LS6 Intake plentem
Ported mass airflow
ported throttle body
Carbon fiber airlid

polyuritane transmission mount

**jetaws6** · 07-13-2011, 07:13 AM

yea get some 42's your duty cycle is gonna be probably gonna be over 100% with the heads

**PFM** · 07-13-2011, 07:22 AM

I didn't have to change my stock injectors until I installed a Fast 90/90 setup. After that I went the Ford 42# but could have gotten by on 36# injectors. Since our fuel pressure is higher a 42# ford injectors equals out to be like a 50#er.

**Edward-T** · 07-13-2011, 07:23 AM

ok, thanks. any brand better than the other or does it matter really?

**PFM** · 07-13-2011, 07:28 AM

Originally Posted by Edward-T

ok, thanks. any brand better than the other or does it matter really?

Everybody I know likes the Ford 42#s. You can usually pick up a set for $200 around our area.

**SSwt00SS** · 07-13-2011, 10:48 AM

agreed, with your setup, get 42's. I'm running 42 with my set-up, and no worries about the duty cycle. the Ford's PFM mentioned are commonly referred to as 'green tops' since the top of the injector is green.

for the life of me, i can't remember what brand mine are. regardless, no issues since installed. i chose to upgrade injectors when i decided to install and U/D pulley and EWP. my H/C/I/E were done and i was around 93% duty cycle. so for me, it was clear i needed to setup.

EDIT: i'm running Lucas 42lb/hr injectors