Daz

iTrader: (1)

Im finishing off my engine build-up and now and it comes to the injectors.
52mm TB,Superram/Bigmouth base,TFS G1 heads (pocket ported),5.7 rodded 383 with 10.25-10.5:1 compression,cam is comp cams Duration@.50 220/230,.510/.510 114LS 27H r14.

The formula suggests that these injectors will be JUST enough.But what happens when they get dirty/old.How necessary are the 24lb injectors in this setup?20lbers?

RB83L69

The 22s might be enough, depending on a number of factors (chip, fuel pressure, etc.) but they also might not. IMHO you probably do need a set of 24s though, they will behave more predictably and controllably at that much fuel flow than the smaller ones.

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"So many Mustangs, so little time..."

AZDave

RB83L69 is on top of this one.
You may not absolutely need 24 lb. injectors, with the right fule pressure, pulse width modifications from a custom chip, etc. - 22 lb. injectors at the max might get it done.
Why not take the easier route and use the less stressed injectors and give yourself some room for further mods.

Dan87IROC-Z

With as much air as you will be moving through that engine, the 24 lb will do a much better job at high RPM. I know a guy with a GTA that had complete exhaust mods, 52mm TB, chip, K&N cold air induction kit, and he ran 24 lb injectors up here at 5000 feet, the car ran a bit rich below 2500rpm, but after that it was perfect, so 24 lb will work GREAT with your set up.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission

Current Mods: Edelbrock TES Headers, Hooker Cat-Back System, Performance Resource Chip, 160* Thermostat, Accel 8.8mm Ignition Wires, K&N high flow air filters, gutted air box, gutted MAF sensor, Throttle Body Coolant By-Pass, Homemade Ram-Air, Falken ZIEX Z-Rated Tires.

1/4 mile times without chip:
Best ET: 15.7 @ 89MPH
Best Corrected ET: 14.5 @ 96MPH

Daz

iTrader: (1)

Would 30 lbers be overkill??

Daz

Guest

It might be. I'm trying to decide on 24's or 30's myself. Im running about the same cam, but on a 350, and its leaning out at higher RPM's. You can easily drown a motor with too much injector.

89gta383

iTrader: (5)

Nope. I'm running 30's with no problems. Get yourself a custom chip, and you'll be fine.

doc

Go with 24#/hr fuel injectors for your 383 setup. The 30s are definitely overkill, you will be running rich at low rpm.

Get the 24s along with a custom chip.



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'87 L98 TPI IROCZ, TF heads, 3.70 gears, LT1 cam?, 2400 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB, TB airfoil, TB coolant bypass, AFPR(48psi), K&N filters, Hotchkis lowering springs, Car-Pro custom chip, Lay Ind. ram air kit, 265/45R16 Kumho V700 tires, and still as slow as hell 13.82sec ET @ 106.3 mph. To be installed soon: TPIS ZZ9 cam, 2400 stall converter.
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow lid, K&N filter.
313.7Hp & 320.6ft-lbf

TRAXION

The 30's will not be overkill if you know how to custom tune a PROM. If you run the 22lb injectors you will see 100+% Duty cycles. The 24lb injectors at 50psi will yield 90+% Duty Cycles.

The 30lbers would be the better choice. However, if you cannot custom tune your own PROMs (or have somebody knowledgeable do it for you) then stick with the 24's so that you don't run rich at idle.

I'm putting 30's on my 350 and I don't expect to have any 'rich' problems at idle after I get the tuning worked out. The great thing about the 30's is that you will have very very reasonable Injector Duty Cycles and you can run at 45psi which is what your fuel pump will like.

Tim

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TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr)
All Natural. No Force. No Drugs. Stock Bottom End.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.

doc

TRAXION,
I'm very interested in knowing how the 30#ers will work out for you. Every book on fuel injection that I have read and my own scan data on my car tells me the 30s are way overkill on a 350 unless its supercharged. One book mentioned that you should not run the fuel injectors under 1.5msec or over 80% duty cycle. I have 22s in my engine and I'm running about 1.8msec at idle.
Just very curious, no flames here.