LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

AFPR and injector sizing question

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Old Jan 22, 2004 | 11:18 AM
  #1  
GREGG 97Z's Avatar
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From: Reading, PA
AFPR and injector sizing question

I noticed in another post here that someone mentioned increasing fuel pressure to the fuel rail could help make up for undersized injectors. I have the stock 24# injectors and based on my last dyno (327rwhp with a miss at the time that has been corrected) and current trap speeds (115) I beleive it may be making around 335-340rwhp. I have installed a 255lph Walbro pump but I am still using the stock FPR. I thought the stock 24# ers were ok for a stock head, hotcamkit/bolt on car and I hadnt planned on replacing them until I went with a bigger cam/heads but that post has me wondering if I could be pushing the duty cycle too high.

My question is would it be a good idea for me to increase the fuel pressure at the rail in the meantime with an AFPR (which I have had but not installed yet) by a few pounds to help reduce a possible high duty cycle or is that just a bad idea without knowing the exact duty cycle (not sure how to calculate it honestly). Last time I checked it was at 43 lbs at the rail with just the key on. Thanks.
Old Jan 22, 2004 | 11:35 AM
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QCKZ28's Avatar
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From: Christiansburg, VA
you have to program the injector constant in your PCM to 30#
and increase your fuel pressure to 58psi.
yes it will work, but this is just a bandaid.

you need bigger/better injectors...
#30 SVO would work perfect.

jesse
Old Jan 22, 2004 | 11:38 AM
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here is a thread i started:
http://web.camaross.com/forums/showt...=fuel+pressure

jesse
Old Jan 22, 2004 | 11:52 AM
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GREGG 97Z's Avatar
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I kind of figured it wouldnt be a good idea to just increase the pressure to make up for it but wanted to check. Thanks for the info.
Old Jan 22, 2004 | 11:56 AM
  #5  
QCKZ28's Avatar
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Originally posted by GREGG 97Z
I kind of figured it wouldnt be a good idea to just increase the pressure to make up for it but wanted to check. Thanks for the info.
i ended up going with a bigger injector too and reducing the fuel pressure.

jesse
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