I am getting ready to order my injectors and I am not sure what size to get. I have searched in the archives, but that yeilded zilch. I have a 383 stroker with the WP sportsman II heads.(64cc/2.02/1.60) The cam lift is .452/.465 and the duration is 214/220 with a lobe separation of 112 degrees. I am using the stock TPI intake, it has been ported and polished, with a 52mm TB. I have the Walbro 255LPH high pressure pump and an AFPR. I have heard different stories as to what to use. I am leaning towards using 30lbs@50psi. Would it be better to use 24lbs at a higher pressure? I have Accel DFI so I can program for either. Which would work best?

Robert

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1989 GTA TRANS AM
Was a TPI 305 & t-5 car.
Is now 383 stroker w/ the same T-5
World products Sportsman II heads. Lunati pistons and custom ground camshaft. Will dyno after the break in but is estimated at 450 hp and 520 ftlbs. The T-5 is on a suicide mission.

 

30lbers definitely.

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91 Formula
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 polished kit, SLP airfoil, ported/polished plenum, March pulleys, Crane AFPR(43psi),Crane Gold 1.6rrs,MSD coil,MSD6AL (5200rpm limit),Holley 9mm wires,Ac delco R43ts plugs,stock chip,Ford SVO 24# injectors,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

 

The 24# would be ok but near maxed out. The 30# will support future mods. You won't necissarily need to run them at 50 PSI. As long as you have at least 40 PSI they will have a good spray pattern & atomization. Between 42-45 PSI should be fine.
30# aren't all that big but running higher pressures will increase their output volume even at idle.
The problem with running larger injectors is idle quality. The reason is that the injector pulse width must be so short that fueling isn't stable. Because of this, running higher fuel pressures can make an engine with 30# injectors not idle as good as it could. 30#ers are a good size though for good HP coverage with good idle fuel control.

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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro
"Cogito ergo zoom"

• 355 cid
• AFR heads
• Arizona Speed & Marine hydraulic roller cam w/ AFR hydra-rev kit
• modified SLP runners
• TRW forged pistons/ceramic coated
• fully balanced
• Edelbrock headers/ceramic coated
• SLP cat-back
• Paxton supercharger
• Nitrous Express nitrous oxide

My IROC-Z
EFI Performance Club on Yahoo
Club IROC-Z

[This message has been edited by IROCKZ4me (edited March 12, 2001).]

 

I would install 24#/hr SVO injectors, these are rated at 26#/hr at the GM pressure. I think that the idle quality for the 30#/hr injectors would be poor. If at idle, the injector pulse width is less than 1.5msec, you have too large injectors.


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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 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 with airfoil, TB coolant bypass, AFPR(58psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.39sec @ 107.21mph
'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 airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph