LT1-LT4 Modifications 1993-97 Gen II Small Block V8

30lbs Injectors

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Old 12-04-2007, 08:06 AM
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Default 30lbs Injectors

My 96 LT1 355 has ported heads, stock valves, 52 MM TB, Pacesetter LT's, and a CC 280 XFI. On the Dyno it was leaning out around 4K rpm's and stayed between 13 and 14.1 through out the rest of the run to 6K rpm's. I have stock injectors w/ 50psi of fuel. Changing fuel pressure didn't seem to make any difference. I was reading the LT1 article in Car Craft and noticed they were using 30 lbs injectors. I have heard stock injectors are good to around 450 HP, but I heard alot of BS too. I made 371 rwhp and 351 rwtq, would bigger injectors help, do I need a retune, or am I just wasting money and gas!
Old 12-04-2007, 09:15 AM
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A lot would go into making an injector swap; are you using the original fuel pump?(could be going out), what duty cycle are your stock injectors running at when the car was getting tuned? Are you planning any future mods? etc.
Old 12-04-2007, 11:26 AM
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Upgraded injectors would help your lean situation.
Old 12-04-2007, 11:47 AM
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I would change them. I am going to change mine i am going to run nitrous!!
Old 12-04-2007, 01:06 PM
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I would not jump to the injectors yet.

duty cycle ?
fuel pressure under WOT ?

I would think at your level the injectors would still keep up. The 30's would be a wise upgrade, but my point is make sure your pump is keeping up as well before you go back to the dyno.
Old 12-04-2007, 10:20 PM
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I know I'm at 50 psi at idle w/ vaccum disconnected. I don't know what it is at WOT. The fuel pump is a stock replacement installed in 2001. How do I figure out what the duty cycle is on these injectors and what I'm at now. I don't plan on any other modifications now, maybe a turbo later but thats ALOT later! Thanks for the help.

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Old 12-04-2007, 10:36 PM
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Originally Posted by 96LT1355Z28
. I have heard stock injectors are good to around 450 HP, but I heard alot of BS too. I made 371 rwhp and 351 rwtq, would bigger injectors help, do I need a retune, or am I just wasting money and gas!
that is 450 fwhp

dont run the car over 14:1 afr bad things will happen
Old 12-05-2007, 04:19 AM
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After using the calculator in the drag racing section, it said I need 33lb injectors. Suggestions?
Old 12-05-2007, 04:52 AM
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Originally Posted by 96LT1355Z28
After using the calculator in the drag racing section, it said I need 33lb injectors. Suggestions?
um... get some bigger injectors?

You pretty much answered your own question.
Old 12-05-2007, 04:16 PM
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I do agree you should have 30# inj, but do not feel with that much fuel pressure and your current HP posted the car should be that lean.

Dave J : how do you get 450 crank HP ? That would be over 20% due to driveline loss.

are you clarifying what they can support ?



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