Stuck lifter? - Page 9 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 04-24-2010, 12:54 PM   #81
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Ya, that would explain the slightly lower flow. So L67 injectors should come in around 30 pounds. I don't suggest going any larger then that because then your under driving the injectors. I ran my L67 injectors up to 98% before I upgraded to 42.5#
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Old 04-24-2010, 12:59 PM   #82
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Ya, that would explain the slightly lower flow. So L67 injectors should come in around 30 pounds. I don't suggest going any larger then that because then your under driving the injectors. I ran my L67 injectors up to 98% before I upgraded to 42.5#
A guy on the w-body forum mentioned I shouldn't go above 80%. Is there a danger to running as high as I'm running right now? 93% duty cycle is pretty high.
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Old 04-24-2010, 01:01 PM   #83
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With a good tune, you might find your fine. Hard to say until you get to that point. Do you know off hand what your AFR is at WOT when your running at 93%?
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Old 04-24-2010, 01:15 PM   #84
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With a good tune, you might find your fine. Hard to say until you get to that point. Do you know off hand what your AFR is at WOT when your running at 93%?
I have 3 WOT runs recorded here for 1-2 shifts. I believe my shift point may be higher for 2-3, and I'm not sure if I'm going to alter my shift points once I start tuning.

5285 RPM
93.1% Injector Duty Cycle
11.6 AFR

5306 RPM
93.3% Injector Duty Cycle
11.9 AFR

5221 RPM
92.7% Injector Duty Cycle
11.8 AFR

KR was at around 5 at each of those points, if that matters at all.
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Old 04-24-2010, 01:23 PM   #85
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To many cars to remember all the details. This was a top swap right? If so, that AFR is correct and no need to change injectors. If this is a NA car, then it'* lean and you might run out of injector. I would deal with getting a good tune and deal with one thing at a time.
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Old 04-24-2010, 01:32 PM   #86
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To many cars to remember all the details. This was a top swap right? If so, that AFR is correct and no need to change injectors. If this is a NA car, then it'* lean and you might run out of injector. I would deal with getting a good tune and deal with one thing at a time.
Its an N/A L27. Ported heads, ported LIM, modified UIM (runners shortened), 1.8 ratio roller rockers. Everything changed once I ported the heads.
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Old 04-24-2010, 01:37 PM   #87
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Yep, once you change the air flow, it throws everything off. I say balance in your VE table first, then see how everything else looks.
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Old 04-24-2010, 02:51 PM   #88
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How do you figure that an AFR of almost 12 is too lean for an N/A engine? I thought in regard to power. 12.9:1 is the best ratio.
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Old 04-24-2010, 04:51 PM   #89
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Just did some checking and yep, your right. When I was much younger 10.9:1 was where people would shoot. Now I see that'* all different. 13.0:1 for a NA car, even as high as 13.5:1 That opens up a lot of room on your injectors.
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Old 04-24-2010, 05:31 PM   #90
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Just did some checking and yep, your right. When I was much younger 10.9:1 was where people would shoot. Now I see that'* all different. 13.0:1 for a NA car, even as high as 13.5:1 That opens up a lot of room on your injectors.
Yeah. That would imply that I'm running way too rich as it is, so if I eliminate knock and get to 12.5 (which is what I'd aim for), I should be good to go.
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