TBIWorks

iTrader: (2)

Okay guys, let's clear this injector# thing up once and for all. Here is my story: I'm building a 5.7 L05 for my RS. I'm using a zz3 cam, edelbrock 6085 heads, and forged flat-tops. The block is decked so the motor should have just over 10:1 compression. I also have a good flowing exaust system. Since I have not decided what permanent induction to use(Holley 670, 454TBI, or DFI), I am planning on slapping on my L03 305 TBI for the time being with the edelbrock perfomer TBI manifold. The absolute closest motor to what I'm building is a ZZ3, except I will have a tad more compression, and better flowing heads. So I will be making ball park HP of 350-375 range.

Having said that, I need to know what size injectors I need to run to feed it up to around 6000 rpms. I have heard 10 different conflicting stories and I need to clear this up with some of you fellow TBI guys who may have a similar setup. I can either chnge the pressure regulator spring in my TBI, or get an adjustable fuel pressure regulator from TurboCity, so expect 12-15psi. Will a set of L05 350 injectors work(62# I think)? Another route I was considering was 454 injectors(75#), or I have heard GM makes 68# too. Some have said I need 85 or 90# but that seems too much, I don't want it to run rich, and remember, for the time being, I'm going to try my stock TBI instead of a bigger bore one. I will most likely attempt to run the motor on my L03 computer, but if necessary, I will get a cop car Prom. Thanks for reading this guys, and lets here some examples!

TBIWorks

iTrader: (2)

c'mon guys, help me out here...

JPrevost

Why don't you want to run rich? If you want to run lean that's a car I'd hate to have invested money into. Lean condition costs $$$, Rich costs $16 (new spark plugs).
GM crossfire injectors are 67# but if you want to just save money and wait, just slap on the 350 injectors with cranked fuel pressure. Without a custom eprom your combo will make like 280-300hp max, unless you used larger injectors. My eye is on getting some 90# GM injectors for when I do my hot cam swap (420hp).
The stock injectors from the 305 will feed your motor till about 3000rpm with cranked fuel pressure. If it's a temp fix then it should work but without a custom eprom your engine is gonna run like crap nomatter what size injectors you use.
If you don't believe me, I don't care. I burn my eproms and I've got enough proof that'll say you'll be swapping to a carb REALLY soon. Some people have the patience for EFI, some don't. TBI is the easiest EFI but it's still speed density so without a custom eprom you're timing, fuel, and everything else is gonna be crap. You basically have 3 options when you ignore the eprom. Either you tune for a decent idle (crap light throttle and terrible WOT), tune for light throttle (crap idle and crap WOT), tune for WOT (terrible idle and crap light throttle).
Sorry to bring bad news but whatever you do, don't run lean!

TBIWorks

iTrader: (2)

JPrevost, trust me, I know I don't wanna run lean, all I was saying is that I don't want to be puffing black smoke. Tell me what you think about this setup as a permanent one with that motor. Holley TBI with no injector pod.(I heard it is available without). Then a GM injector pod with stock 454 injectors, and a urbo city adjustable fuel pressure regulator. Enough fuel??? that is waht I'm asking for. Also, I definitley will have a different chip burned for me, I was just wondering if it would run on the stock chip. I live in Oklahoma, about 2 hours from Ed Wright Auto; fastchip.com. So what's the verdict, I know you use the Holley, what injectors are you using dude? I want to make 350hp with TBI!!!